Pediatric Plastic and Reconstructive Surgery

primary repair, local tissue rearrangement, and/or lengthening
procedures. Situations arise in which a defect is otherwise ame-
nable to local flap reconstruction, but the surrounding tissues
have been scarred by multiple previous operations. In such
cases, tissue expansion has shown great utility. Tissue expan-
sion can also be useful in conjunction with lengthening proce-
dures and repair of hypospadias (Fig. 30.5). However, when a
satisfactory result cannot be achieved with less complex proce-
dures, phalloplasty to reconstruct the entire penis with
pedicled locoregional flaps or free tissue transfer can be
considered.
The genital defects associated with EEC can pose a di cult
reconstructive challenge. Management often involves staged
reconstruction of the bladder, urethra, abdominal wall, and
genitalia, and requires close coordination and cooperation
between the reconstructive surgeon and urologist. The genital
defects associated with EEC vary in severity. In isolated epispa-
dias, the urethral meatus is located on the dorsal surface of the
penis at the penopubic angle and the glans is open dorsally. The
phallus is typically shortened with dorsal chordee. Epispadias
can sometimes be managed with standard lengthening proce-
dures; however, phalloplasty can be used to achieve favorable
results in severe cases. In cases of exstrophy, the penis can be
halved and separated from the midline. In such cases of severe
deformity, phalloplasty is indicated.
In the past, aphallia and severe congenital penile defects
were treated with gender reassignment, with bilateral orchiec-
tomy, penectomy (when a penis was present), labioplasty, clito-
roplasty, and vaginoplasty. The realization that these patients
typically maintain a male identity following surgery, as well as
the emergence of e ective techniques for phalloplastic recon-
struction, has resulted in this practice falling out of favor.
Table 30.1 Common congenital genital anomalies
Condition

Definition

Etiology

Incidence
Penile anomalies
Micropenis

Normal proportions but <2.5
standard deviations below appro-
priate size for age.
Insufficient androgen stimulation in
utero with defect in hypothalamic-
pituitary-gonadal axis
1:200
Hypospadias

Urethral malformation with ventral
termination, often with ventral soft-
tissue defect and chordee.
Unclear

1:250
Ambiguous genitalia

Appearance of genitals not clearly
male or female.
Congenital adrenal hyperplasia
Leydig cell failure
Testosterone biosynthesis enzyme de-
fects
Androgen insensitivity syndrome
Congenital anorchia
Gonadal dysgenesis
Klinefelter syndrome (47,XXY)
1:4,200
Epispadias

Urethral malformation with dorsal
termination, often presenting with
small bifid penis.
Failure of mesodermal migration with
premature rupture of cloacal mem-
brane. Failure of midline fusion of
genital tubercles.
1:120,000
Bladder exstrophy

Abdominal wall defect, pelvic dia-
stasis, penile defect, epispadias,
bladder open and exposed
Failure of mesodermal migration with
premature rupture of cloacal mem-
brane. Failure of midline abdominal
wall fusion after separation of genito-
urinary and gastrointestinal tract.
1:10,000–1:50,000
Cloacal exstrophy

Abdominal wall defect with extru-
sion of hind gut, cecum and split
bladder, penis and scrotum
Failure of mesodermal migration with
premature rupture of cloacal mem-
brane. Failure of midline abdominal
wall fusion before separation of geni-
tourinary and gastrointestinal tract.
1:200,000–1:400,000
Aphallia

Agenesis of penis

Failure of the cloacal folds to generate
genital tubercle
1:10,000,000
Vaginal anomalies
Transverse vaginal septum

Tissue bridge across vaginal vault
Improper fusion of Muellerian ducts to
urogenital sinus
1:30,000–1:80,000
Longitudinal vaginal septum

Longitudinal tissue bridge dividing
vaginal vault
Incomplete fusion of lower Muellerian
ducts
1:10,000
Vaginal agenesis

Absence of vagina

Unclear

1:10,000
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284

30.4.2 Phalloplasty
The goals of phalloplastic reconstruction include formation of
an aesthetically acceptable neophallus, a competent urethra
allowing for voiding while standing in those patients who do
not have continent urinary stomas, enough sti ness to allow for
sexual penetration, erogenous and protective sensation, and
minimal donor site morbidity. Over the past century, the surgi-
cal approach to total phalloplasty has undergone significant
evolution. A number of approaches have emerged, each of
which provides some, but not all, of the ideal characteristics of
a neophallus. The earliest techniques utilized pedicled flaps
from the abdomen and groin. More recently, with the advent of
microsurgical technique, a number of options involving free tis-
sue transfer have gained popularity. Because they typically pro-
vide better function, sensation, and aesthetic outcomes, free
flaps have largely replaced pedicled options for phalloplasty.
The pedicled abdominal flap was the first type of flap used for
total penile reconstruction. It is essentially a pedicled, tubular-
ized rectus abdominus myocutaneous flap based on the deep
inferior epigastric vessels. An implant is typically inserted to
allow for sexual function. Although a reasonable option when
microsurgical capabilities are lacking, this flap lacks sensitivity
and the aesthetics are often poor.
The pedicled groin flap is an axial flap based on the superficial
circumflex iliac vessels, allowing for single-stage reconstruc-
tion, with or without an implantable device to provide sti ness.
Iliac crest can also be incorporated. Like the pedicled abdominal
flap, the pedicled groin flap is limited by poor sensation and
aesthetics. Furthermore, it has been noted that the groin flap
often results in a small neophallus because of the limited tissue
available. Given these limitations, the groin flap for phalloplasty
has largely fallen out of favor.
The radial forearm free flap (RFFF) has gained popularity
and is considered by many to be the contemporary gold stand-
ard for phalloplasty. The RFFF is well suited for neophallus crea-
tion in part because it is relatively thin, supple, and hairless,
thereby mimicking penile shaft skin. With additional modifica-
tions to define the penile subunits, the RFFF now allows for
much improved aesthetic outcomes (Fig. 30.6). Furthermore,
because it receives robust sensory innervation from both the
medial antebrachial cutaneous (MABC) and the lateral antebra-
chial cutaneous (LABC) nerves, the neurotized RFFF can provide
Fig. 30.1 An adolescent male with micropenis.
Fig. 30.2 A male patient with ambiguous geni-
talia. Note micropenis resembling clitoris.
Genital Anomalies
285

excellent erogenous and protective sensation, and patients
often report the ability to orgasm (Bluebond-Langner and
Redett 2011). In order to achieve rigidity, an implant is often
inserted in a second stage. However, use of an implant does
introduce a risk of extrusion. An alternative approach to pro-
vide rigidity without an implant involves harvesting a portion
of the radius within the flap; however, this approach is limited
by the nuisance of permanent rigidity and a high rate of bone
resorption. In addition to prosthesis extrusion, all the fasciocu-
taneous flaps are prone to high rates of urinary fistulae and
strictures. An additional disadvantage of the RFFF is the con-
spicuous donor site that carries the stigma of gender reassign-
ment in the transsexual community.
The anterolateral thigh flap (ALTF) is a fasciocutaneous perfo-
rator flap based on the descending branch of the lateral circum-
flex femoral vessels. It can be used free of pedicled flap for
phalloplasty (Fig. 30.7). This flap has a number of potential
advantages over the RFFF including a less conspicuous donor
site, skin that is potentially less pigmented, and greater soft-tis-
sue bulk (Reiner and Gearhart 2004). However, the skin of the
ALTF is often much thicker, less supple, and hairier than that of
the RFFF. Furthermore, the ALTF is not a good option for patients
with large amounts of subcutaneous fat given the di culty this
poses with tubularizing the flap. Like the RFFF, the ALTF can be
neurotized for sensation via the lateral femoral cutaneous nerve
of the thigh; however, it appears to provide significantly less
erogenous sensation in comparison to the RFFF.
The latissimus dorsi myocutaneous flap (LDMF), based on the
thoracodorsal vessels, is a reliable option for phalloplasty that
provides considerable soft-tissue bulk. Modifications to the
LDMF for neurotization have been described, using ilioinguinal
to thoracodorsal nerve coaptation. Although protective sensa-
tion has been reported using this technique, the mechanism by
which this occurs is unclear given that it involves sensory
regeneration into a motor pathway. Approximating the thora-
codorsal nerve of the flap to the nerve to the gracilis has also
been reported, with patients reportedly able to voluntarily con-
tract the latissimus muscle within the flap so as to achieve pen-
etration without an implant.
Fig. 30.3 A newborn male with bladder exstrophy. Note short urethral
plate, scrotal flattening, and chordee. (Adapted from Gearhart JP, Jeffs
RD. The bladder exstrophy-epispadias complex. In: Walsh PC, Retik AB,
Vaughan ED, et al, eds. Campbell’s urology. 7th ed. Philadelphia, PA:
WB Saunders;1998:1939–1990.)
Fig. 30.4 A newborn male with cloacal exstrophy.
(This image is provided courtesy of Dr. John
Gearhart.)
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286

Fig. 30.5 Illustration of hypospadias reconstruc-
tion using tissue expansion. (a) Tissue expanders
under penile shaft skin. (b–d) The neourethra
created using residual urethral plate and ex-
panded shaft skin and covered with fibrous
capsule, which formed around tissue expanders.
(e,f) Reconstructed phallus with meatus and tip
of glans. (Adapted from Rochlin et al. 2014.)
Fig. 30.6 Preoperative photo of male with blad-
der exstrophy and associated micropenis preop-
eratively (a) and postoperatively (b) after radial
forearm free flap phalloplasty.
Genital Anomalies
287

The fibula osteocutaneous free flap (FOCFF), based on the
peroneal vessels, has also been used for phalloplasty. The FOCFF
can be neurotized via the lateral sural cutaneous nerve,
although the sensibility of the flap is poor in comparison to the
RFFF. The primary advantage of the FOCF is inclusion of a por-
tion of the fibula to allow for penetration without an implant.
Despite the value of intrinsic rigidity provided by this flap,
there are obvious disadvantages to a permanently erect neo-
phallus that can be di cult to conceal and uncomfortable. Fur-
thermore, the bony component within the flap is susceptible to
resorption and warping.
30.4.3 Preoperative Planning
Prior to proceeding with phalloplasty, it is important to identify
which components of the native penis can be incorporated into
a neophallus. If a functional glans is present, it can be incorpo-
rated into the ventral base of the neophallus to augment eroge-
nous sensation and provide an ejaculatory duct in those
patients with a urinary stoma who are not candidates for crea-
tion of a neourethra to the tip of the phallus. When the corpora
are present and salvageable, they can also be used for soft-
tissue bulk and sti ness within the flap, as well as to help
seat an erectile implant. However, incorporation of native
components may not be an option, such as in aphallia or
other severe malformations. The length and patency of the
urethra as well as the status of the more proximal urinary
system should also be considered preoperatively. Reconstruc-
tive goals should include urination through the neophallus
when possible. However, many children with bladder or cloa-
cal exstrophy undergo bladder neck transection and creation
of an umbilical continent urinary stoma. In such cases, the
native urethra is still brought out through ventral base of the
neophallus to allow for ejaculation, but the patient will con-
tinue to catheterize the umbilical urinary stoma following
reconstruction.
Beyond assessing the genital defect, it is also important to
determine whether any associated deficits or comorbidities
would preclude or minimize the utility of phalloplastic
reconstruction. It is also important to carefully explain the
reconstructive options with the patient’s caregivers prior to
proceeding. Older children and teenagers should be included in
these conversations and should play a central role in decision-
making. We generally wait until after puberty to perform total
phalloplasty reconstruction. Setting realistic expectations for
patients and families is critically important.
30.4.4 Surgical Approach to the Radial
Forearm Free Flap for Phalloplasty
The RFFF is considered by many to be the gold standard for
phalloplasty and is our preferred method for pediatric patients.
To perform the RFFF, the patient is placed in the supine position
with the upper extremity from which the flap will be harvested
abducted and supinated. A sterile upper extremity tourniquet is
used during flap harvest for hemostasis. The flap is marked
with dimensions of 14 ×14 cm 2. This typically includes the
entire width and up to three-fourth of the length of the volar
forearm, beginning distally at the proximal wrist crease
(Fig. 30.8a and Fig. 30.9). Prior to elevating the flap, the
neo-glans is defined by raising a transverse split-thickness skin
flap across the distal forearm and rolling it under itself where it
is secured with resorbable sutures. The donor site of the glans
flap is later covered with a full-thickness skin graft to better
define the corona and give the penis the appearance of having a
circumcision scar ( Fig. 30.8b). This coronal glans flap can also
be created once the neophallus is tubed, but we find it easier to
raise before the flap is harvested. For patients who require a
neourethra, a central longitudinal strip of skin is de-epithelial-
ized, separating the ulnar-sided skin panel (which will line the
neourethra) and the radial-sided skin panel (which will provide
the external skin of the neophallus).
The RFFF is then raised in a standard fashion from distal to
proximal in standard fashion. The radial artery and venae com-
itantes between flexor carpi radialis and brachioradialis are
ligated at the level of the wrist and elevated with the flap from
the underlying tendons. Care is given to preserving the parate-
non to allow for skin grafting the donor site. The palmaris
Fig. 30.7 Preoperative markings for pedicled
anterolateral (ALT) for phalloplasty.
Trunk and Lower Extremity
288

longus tendon is included in the flap for use in anchoring the
neophallus to the pubic bone. The MABC and LABC nerves and
the cephalic vein are identified proximal to the flap and har-
vested with the flap. The flap is tubularized on the forearm
before transecting the pedicle ( Fig. 30.10). This involves roll-
ing the flap from ulnar to radial to form the neourethra with
the ulnar-sided skin panel. Once the ulnar skin paddle in
internalized, the flap is rolled under itself to externalize the
radial-sided skin panel. The de-epithelialized central panel is
buried within the flap ( Fig. 30.8c).
Preparation of the recipient site and flap elevation can be
performed simultaneously if two surgical teams are available. A
pediatric urologist is ideally present to assist with recipient site
preparation.
Fig. 30.8 Illustrations of key steps of radial forearm free flap phalloplasty. (a) Flap outlined with important neurovascular structures to be included in
flap. (b) Glansplasty and coronaplasty. Skin flap is sutured under itself to create glans. Full-thickness skin graft is applied to donor site of glans flap to
create appearance of circumcision scar at corona. (c) Flap being rolled from ulnar to radial. Ulnar skin flap is rolled over itself to create neourethra.
Central de-epithelialized skin is buried in flap. Flap is then rolled under itself to externalize the radial skin. (d) Native glans inset into ventral base of
neophallus in those patients who are not candidates for urethral reconstruction. (e) Flap transferred showing vascular anastomoses and nerve
coaptations.
Genital Anomalies
289

If the native penis is to be incorporated into the neophallus,
the shaft skin is removed and internal structures including ure-
thra and the penile nerves are deconstructed. When a compe-
tent urethra in continuity with the proximal urinary tract is
present, the corpus spongiosum is severed from the glans so
that it can be anastomosed to the neourethra within the flap.
However, when the bladder neck has previously been trans-
ected and the patient voids from an umbilical stoma, the ure-
thra is left in continuity with the glans, and the external
meatus is externalized through the ventral base of the neophal-
lus to allow for ejaculation (Fig. 30.8d). In either case, the
glans is incorporated into the neophallus. To do this, it is de-
epithelialized and buried into the base of the neophallus, either
at the time of phalloplasty or, more conservatively, at a later
stage to account for possible flap failure.
The dorsal penile nerves for erogenous sensation, and either
the ilioinguinal or iliohypogastric nerve for protective sensa-
tion, are dissected in the pelvis and approximated to the MABC
and LABC nerves of the flap. A number of possible recipient site
vessels can be anastomosed to the radial artery to perfuse the
Fig. 30.9 Preoperative markings for radial fore-
arm free flap for phalloplasty.
Fig. 30.10 Intraoperative photograph of radial forearm free flap
tubularized and prelaminated on forearm prior to transfer.
Trunk and Lower Extremity
290

flap, including the superficial circumflex iliac, inferior epigas-
tric, external pudendal, and femoral arteries. The accompanying
veins, as well as the greater saphenous vein, can be used to pro-
vide venous outflow via the venae comitantes of the radial
artery and the cephalic vein. We perform as many venous anas-
tomoses as possible to help reduce postoperative swelling and
venous congestion (Fig. 30.8E).
The neourethra within the flap is anastomosed to the native
urethra over a 10 or 12 French urinary catheter at the time of
phalloplasty. Although the senior author’s preferred method for
neourethra construction is described above, alternative
approaches include prelaminating the flap with a full-thickness
skin graft or inserting a tubed skin or buccal mucosal graft at a
later stage.
Insertion of the penile prosthetic implant is performed at a
later stage and is typically delayed until late adolescence or
early adulthood to minimize implant-associated risks, including
soft-tissue erosion, infection, and extrusion. Prior to implant
insertion, protective sensation should be present and the pa-
tient should exhibit a high level of maturity. We wait a mini-
mum of 1 year after phalloplasty before inserting the implant
to insure the return of protective sensation before the
procedure.
30.5 Complications
The RFFF is the most popular option for phalloplasty because it
allows for excellent aesthetics as well as consistent erogenous
and protective sensation. However, as with all methods of phal-
loplasty, there are significant limitations to the RFFF that must
be given serious consideration. While all of our patients who
underwent RFFF phalloplasty report the ability to achieve
orgasm and satisfaction with neophallus appearance, we have
also noted that roughly half of our patients experience signifi-
cant complications involving urinary strictures and fistulae
and/or implant-associated complications requiring implant
explantation; these findings are consistent with other large
series.
30.6 Conclusion
There are a number of congenital anomalies a ecting the penis,
each of which requires a di erent approach to reconstruction.
It is important to understand how the di erent anomalies
a ect normal anatomy as well and the various reconstructive
options that can be used to correct them. A multidisciplinary
team is required to address the urologic, sexual, and psycholog-
ical sequelae associated with genital anomalies. Although
autogenous phalloplasty can o er favorable results, there are a
number of drawbacks including donor site morbidity and com-
plications involving prosthesis extrusion and urinary strictures
and fistulae. Tissue engineering and vascularized composite
allotransplantation may o er improved results in the future.
30.7 Key Points
● Congenital anomalies are the most common cause of penile
defects requiring reconstruction in the pediatric population.
● Genetic males with aphallia, sever micropenis, or ambiguous
genitalia should be considered for phalloplasty; early gender
reassignment surgery for these patients has fallen out of favor
given they often maintain their male identity.
● Congenital penile anomalies resulting from fetal testosterone
deficiency may respond to testosterone therapy.
● Some penile defects can be corrected with tissue expansion,
local tissue rearrangement, and lengthening procedures.
More severe defects require phalloplasty.
● The goals of phalloplasty include formation of an aesthetically
acceptable neophallus, a competent urethra allowing for void-
ing while standing in those patients who do not have conti-
nent urinary stomas, enough sti ness to allow for sexual
penetration, erogenous and protective sensation, and mini-
mal donor site morbidity.
● The authors consider the RFFF to be the gold standard for
phalloplasty because it o ers superior aesthetics and
sensation.
● Complications of phalloplasty include donor site morbidity,
prosthesis extrusion, and urinary strictures and fistulae.
● Tissue engineering and vascularized composite allotransplan-
tation may o er improved results in the future.
Suggested Readings
Bluebond-Langner R, Redett RJ. Phalloplasty in complete aphallia and ambig-
uous genitalia. Semin Plast Surg. 2011; 25(3):196–205
Reiner WG, Gearhart JP. Discordant sexual identity in some genetic males
with cloacal exstrophy assigned to female sex at birth. N Engl J Med. 2004;
350(4):333–341
Massanyi EZ, Gupta A, Goel S, et al. Radial forearm free flap phalloplasty for
penile inadequacy in patients with exstrophy. J Urol. 2013; 190(4)
Suppl:1577–1582
Rochlin DH, Zhang K, Gearhart JP, et al. Utility of tissue expansion in
pediatric phallic reconstruction: a 10-year experience. J Pediatr Urol.
2014; 10(1):142–147
Monstrey S, Hoebeke P, Selvaggi G, et al. Penile reconstruction: is the radial
forearm flap really the standard technique? Plast Reconstr Surg. 2009; 124
(2):510–518
Genital Anomalies
291

31 Lower Extremity
Arin K. Greene and Amir H. Taghinia
Sum m ary
Common indications for lower extremity reconstruction in chil-
dren include the following: constriction ring, lymphedema,
syndactyly, defects following skin lesion removal, and trauma.
Principles of reconstruction are similar to adults. Management
is based on the type of deformity.
Keywords: leg, pediatric, constriction ring, lymphedema, syn-
dactyly, nevus, trauma
31.1 Introduction
In the pediatric population, plastic surgical problems can be
congenital or acquired. The most common idiopathic disorders
managed by plastic surgeons are syndactyly, macrodactyly, con-
striction rings, and lymphedema. Acquired disorders of the leg
frequently arise from trauma or following extirpation of a
lesion. Traumatic injuries are managed similarly to adults. How-
ever, because of the young age of the patients and long pro-
jected lifespan, aesthetic concerns and function are particularly
emphasized by patients/families. We favor managing patients
as low on the reconstructive ladder as possible.
31.2 Diagnosis
Diagnosis of lower extremity disorders primarily is made by
history and physical examination. Traumatic wounds are eval-
uated for tissue loss, nerve injury, fractures, and foreign bodies.
Usually adequate local tissue is available to cover bone or hard-
ware proximal to the knee. Large areas of exposed bone or
hardware involving the knee and midtibia area may be covered
using regional gastrocnemius or soleus flaps. However, the
threshold to use the flaps is higher in children compared to
adults because of the long-term potential of reduced function.
Significant tissue loss involving the lower one-third of the leg
may require free-tissue transfer. Plain radiography is used to
rule out fractures and foreign bodies following major traumatic
injuries. X-ray also is used to assess syndactyly and macrodac-
tyly to determine an underlying osseous abnormality.
The diagnosis of lymphedema can be di cult. The term “lym-
phedema” often is used generically to describe any condition
that causes overgrowth of an extremity; one-fourth of patients
referred to our lymphedema center do not have the disease.
Lymphedema is the chronic, progressive swelling of tissue due
to inadequate lymphatic function. In the pediatric population,
97% of cases are due to maldevelopment of the lymphatic sys-
tem (primary) and 3% are due to inguinal lymphadenectomy/
radiation (secondary). Primary lymphedema a ects 1/100,000
persons and almost always a ects the lower extremity; the
genitalia is the second most common site. Males typically
exhibit bilateral swelling during infancy, while girls usually
present with unilateral edema in puberty.
Lymphedema almost always a ects the distal extremity and
then progresses proximally. If the hand or foot is not involved,
the patient is unlikely to have lymphedema. Over time, subcu-
taneous lymph stimulates adipose deposition and fibrosis,
which causes nonpitting edem a and a positive Stemmer sign
(the inability to grasp the base of the second toe or finger).
Lymphedema is usually painless and does not cause ulceration.
Definitive diagnosis of lymphedema requires lymphoscintigra-
phy; almost all patients referred to our center undergo this
imaging study.
31.3 Nonoperative Treatment
Congenital anomalies do not require operative intervention
unless they are causing a functional or “cosmetic” problem.
Because long-term memory and self-esteem begin to form at
approximately 4 years of age, elective correction of deformities
not causing a functional problem can be performed at 3 years of
age. Alternatively, patients can be observed until they are old
enough to request improvement of a deformity (e.g., syndactyly,
macrodactyly, benign skin lesion).
Most patients with lymphedema do not require operative in-
tervention. Lymphedema is associated with a high risk for infec-
tion; therefore, patients are counseled about washing and
moisturizing the a ected area regularly to prevent desiccation,
skin opening, and cellulitis. Patients are encouraged to partici-
pate in all physical activities, including exercise. The first-line
therapy for lymphedema is compression garments, which
reduce extremity volume and minimizes progression. Pneu-
matic compression devices provide intermittent pressure via an
inflatable sleeve. Pneumatic compression therapy is e cacious,
simple, and convenient because it is performed at home and is
not dependent on a therapist. Complex decongestive therapy
employs skin care, manual lymphatic drainage, compression
bandaging, and exercise. We generally do not recommend this
intervention because it is particularly di cult in the pediatric
population and requires a substantial time commitment for the
patient/family and the reliance on a provider.
31.4 Operative Treatment
31.4.1 Constriction Ring
Constriction ring syndrome (CRS) can a ect any portion of the
lower extremity, though it presents more commonly in the toes.
There is a spectrum of involvement, from superficial scarring to
deep bands down to bone resulting in functional detriment,
growth disturbance, joint deformity (e.g., club foot), and/or dis-
tal lymphedema. The most severe manifestation can be congen-
ital amputation at any level.
Operative treatment of CRS should address the functional
and aesthetic issues of the a ected limb. Collaboration with an
orthopaedic colleague is vital in cases of joint deformity (e.g.,
club foot) or where there is significant restriction of joint
motion. For bands a ecting the legs or thighs, excision and flap
advancement are the ideal treatment. Most advocate treatment
prior to ambulation to take advantage of the extra soft tissue of
Trunk and Lower Extremity
292

an infant and easier immobilization. The authors employ the
technique advocated by Upton. An assessment of tissue laxity
and movement is performed. Bands that are deep and narrow
are ideal as they provide plenty of soft tissue to restore contour.
The ring is then marked and the skin is excised. Separate adipo-
fascial and skin flaps are raised. The adipofascial flaps are
mobilized and closed and then the skin flaps are approximated
ideally away from the line of closure of the adipofascial flaps.
This technique provides the best contour. Z-plasties are advo-
cated extensively in the literature but are rarely needed. If the
ring is deep or if there are multiple closely spaced rings, then a
staged approach may be prudent ( Fig. 31.1).
31.4.2 Lymphedema
A patient must fail conservative therapy and have significant
morbidity before a surgical procedure is considered (e.g.,
psychosocial distress, recurrent infections, decreased function).
Suction-assisted lipectomy is our preferred operative technique
for extremity lymphedema because it gives consistently favor-
able results with minimal morbidity. The technique removes
the abnormally hypertrophied subcutaneous adipose tissue
and reduces excess extremity volume by approximately 75%
(Fig. 31.2). Liposuction does not cure lymphedema, and
patients must continue their compression regimen. Recurrence
has not been noted with 15 years of follow-up. Microsurgical
procedures have been performed using lymphatic-venous anas-
tomosis (LVA) and vascularized lymph node transfer. These pro-
cedures theoretically might have e cacy in mild lymphedema,
before fibroadipose deposition has occurred. However, patients
with mild lymphedema rarely have significant morbidity and
can be managed well with compression. Because patients with
primary lymphedema have hypoplastic or absent lymphatics,
they are poor candidates for microsurgical procedures. LVA and
Fig. 31.1 A young child with a constriction ring of the lower extremity. (a,b) Preoperative appearance. (c,d) After circumferential excision,
advancement of cephalad and caudad fasciocutaneous flaps, and skin closure.
Fig. 31.2 A female with adolescent-onset primary lymphedema of the left lower extremity. (a) Preoperative appearance. (b) Intraoperative view of
subcutaneous adipose removal using suction-assisted lipectomy. (c) Lipoaspirate. (d) Postoperative result.
Lower Extremity
293

lymph node transfer have not shown consistent improvement
in lymph flow and reduction in extremity volume. Lymph node
transfer has been associated with donor site lymphedema fol-
lowing node harvest. Because patients with primary lymphe-
dema are at risk of developing lymphedema in their other
limbs, they are at highest risk for developing donor site lymphe-
dema following removal of lymph nodes.
31.4.3 Syndactyly
Syndactyly most commonly a ects the second webspace in the
foot. In Apert syndrome, the syndactyly a ects all four webspa-
ces but rarely is there bony coalition distally. In most patients,
syndactyly of the foot does not cause major functional prob-
lems. Most children and adults are able to walk, run, and partic-
ipate in sports. Treatment is usually requested by parents in
early infancy or by patients during teenage years as they
become more self-conscious about their appearance.
Under general anesthesia and tourniquet control, dorsal and
plantar triangular flaps are planned for commissure reconstruc-
tion (Fig. 31.3). Plantar zigzag incisions, similar to those
used for release of hand syndactyly, are not needed. Instead,
straight-line releases are used and these rarely result in con-
tractures. The resulting defects are covered with full-thickness
skin grafts from the lower abdomen. Three weeks of cast immo-
bilization and non–weight bearing is critical to allow the skin
grafts to fully take. The ideal time to perform the operation is in
infancy just before the patient begins to ambulate.
31.4.4 Reconstruction Following Skin
Lesion Removal
The lower extremity is an unfavorable location to remove large
lesions of the integument because (1) skin redundancy is mini-
mal, (2) ambulation places tension on the incision line, and (3)
gravity favors swelling, which increases stress on the incision
line. Options to reconstruct cutaneous defects following extir-
pation include (1) allowing it to heal by secondary intention,
(2) linear closure following skin undermining, (3) placement of
a skin graft, (4) tissue expansion, and (5) regional or free tissue
transfer. In extremities, one should consider cast or removable
knee immobilization after lesion excision to ensure better heal-
ing and avoid dehiscence.
Timing of intervention falls into three categories: (1) 6 to 12
months of age, (2) 3 to 4 years of age, and (3) late childhood/
early adolescence. It is best to perform elective procedures after
6 months of age because the infant’s physiology approximates
that of an adult, which reduces the risk of anesthesia. Because
most infants begin ambulating around 12 months of age, it is
preferable to remove lesions before this time to reduce the risk
of suture line dehiscence. If patients present after 12 months of
age with lesions causing a deformity only (e.g., infantile heman-
gioma, benign pigmented nevus), then removing the lesion
before 4 years of age will eliminate the deformity before the
child’s long-term memory and self-esteem begins to form.
Some parents will prefer to wait until a child is old enough to
participate in the decision to extirpate a lesion, which can occur
in late childhood or early adolescence.
Fig. 31.3 Toe syndactyly treated with dorsal and plantar triangular flaps. (a) Preoperative appearance. (b,c) Markings of the flaps that are raised
sharply in the subdermal plane. Once the syndactyly has been released, the flaps are transposed into the commissure. (d,e) Full-thickness skin grafts
from the lower abdomen are used to resurface the skin defects on each side of the web.
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Small defects or areas on the foot that would necessitate
complicated reconstruction can be allowed to heal secondarily
(Fig. 31.4). Allowing the wound to heal by contraction and
epithelialization prevents the risk of infection and suture line
dehiscence. In addition, it facilitates recovery for the patient
who can immediately resume full activity and bathe. Almost all
skin lesions can be removed by lenticular excision and linear
closure (Fig. 31.5); large areas are managed by serial excision
(Fig. 31.6). We prefer this procedure over skin grafting
because grafts leave a large circumferential scar as well as an
indented, hairless area. Many patients are unhappy with the
appearance of a skin graft and request that it be removed. We
believe serial excision is superior to tissue expansion because it
is associated with less morbidity and the child ultimately has a
single linear incision instead of multiple scars from rotation/
advancement of expanded skin flaps. Serial excision expands
the integument without the use of expanders; the technique
involves short outpatient procedures with minimal morbidity
and does not require outpatient injections of saline. External
tissue closure systems can aid the closure of large wounds.
Occasionally, large circumferential lesions require skin grafting
or tissue expansion because serial excision can only be per-
formed if normal skin is present on either side of the lesion
(Fig. 31.7).
Fig. 31.4 A young child with an osseous lesion of the toe. (a) Preoperative view. (b) After resection. The wound was allowed to heal secondarily to
avoid complicated reconstruction. The child was allowed to immediately ambulate and wash the area. (c) Favorable postoperative appearance.
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Fig. 31.5 Immunocompromised child with a
squamous cell carcinoma of the leg. (a) Preope-
rative appearance. (b) Linear closure following
extirpation with wide margins.
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Fig. 31.6 Removal of a large congenital skin lesion. (a) Preoperative appearance of the melanocytic nevus. Outline illustrates the initial area to be
resected. (b) After first-stage resection. (c) Following second-stage serial excision. (d) Final appearance after third-stage removal.
Fig. 31.7 Giant pigmented nevus of the lower extremity. (a,b) Preoperative appearance. Because the lesion was large and circumferential, it was not
amenable to serial excision. The patient underwent tissue expansion of the trunk to obtain adequate full-thickness skin to cover the area following
extirpation. (c,d) Postoperative result after resection and application of a full-thickness skin graft.
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31.4.5 Trauma
Reconstruction of traumatic defects is based on the size, loca-
tion, and depth of the wound ( Fig. 31.8). Superficial areas can
be allowed to heal secondarily (with or without vacuum-
assisted wound closure). Larger defects may be closed with
delayed primary closure (with or without external tissue
expansion; Fig. 31.9, Fig. 31.10). Skin grafts are only neces-
sary if the wound cannot be closed linearly by advancing skin
flaps (Fig. 31.11). Skin grafts should be avoided if possible
because they cause a worse deformity than a linear scar, and
patients often will request that the graft be removed
secondarily.
Deep wounds with exposed bone can be allowed to heal sec-
ondarily (if the area is small), or closed with approximation of
adjacent tissues. Localized areas of exposed bone or tendon can
be managed with vacuum-assisted wound closure to decrease
the area of the wound and generate granulation tissue
Fig. 31.8 Penetrating trauma causing transection of the tibial nerve. (a) Preoperative appearance. (b) Intraoperative view of the divided nerve. (c)
Following nerve repair. (d,e) Good function postoperatively.
Fig. 31.9 Traumatic lower extremity wound with significant skin loss. (a) Preoperative appearance with external fixator in place. (b) Application of
external tissue expander. (c) Negative pressure wound therapy over closure device. (d) Serial delayed primary closure after removal of the wound
closure system and continued vacuum-assisted wound closure therapy. (e) Small wound after completion of serial delayed primary closure and
negative pressure wound therapy. The area was left open to heal secondarily. (f) Closed wound with a linear scar.
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amenable to skin grafting. We do not favor alloplastic substance
(e.g., integra, dermal substitutes) placed over bone or tendon
because vacuum-assisted wound closure will provide adequate
granulation to simplify reconstruction. Large areas of exposed
bone, tendon, or hardware in the lower leg require regional
muscle flap closure (e.g., gastrocnemius, soleus) or free tissue
transfer ( Fig. 31.12, Fig. 31.13, Fig. 31.14).
31.5 Complications
The most common complication following a procedure on the
lower extremity is suture line dehiscence. The larger and more
distal the skin defect, the greater the risk of wound breakdown.
Suture line dehiscence can be minimized using several strat-
egies. First, sutures can be left for at least 4 weeks, when the
wound has achieved 40% of its strength. Second, the patient is
placed in a knee immobilizer for 2 to 3 weeks to limit stress on
the incision line. The knee immobilizer can be removed when
the patient is sleeping. To help prevent the scar from widening
after removing the sutures, it can be taped with steri-strips 6
weeks postoperatively when the scar has achieved its full
strength.
31.6 Conclusion
Lower extremity reconstructive problems in children are di er-
ent than those in adults. Several congenital disorders that
are not managed in the adult population exist. Principles of
extirpation of lesions and reconstruction can be similar to
adults. However, children are less likely to follow postoperative
instructions and tolerate suture removal. Often, immobilization
of the extremity should be performed after an operation. The
pediatric population does not have arterial or venous disease
and thus can best tolerate wide skin undermining and closure
of wounds linearly. In general, children should be managed as
low on the reconstructive ladder as possible.
31.7 Key Points
● Most cutaneous lesions and skin defects in the lower extrem-
ity can be closed with serial excision/delayed primary closure.
● Skin grafts and subcutaneous tissue expanders should be
avoided if possible.
● Maintenance of sutures for several weeks and immobilization
of the extremity can reduce the risk of suture line dehiscence.
Fig. 31.10 Traumatic lower extremity wound managed with delayed serial closure, external tissue expander, negative pressure wound therapy, and a
split-thickness skin graft. (a) Preoperative appearance. (b) Application of external wound closure device and vacuum-assisted sponge. (c) Most of the
wound was able to be closed with delayed primary closure giving a single linear scar. (d) The area involving the knee was unable to be closed linearly
and underwent reconstruction with a split-thickness skin graft.
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Fig. 31.11 A male with a traumatic injury. Because the skin loss was extensive and circumferential, his wound was managed with a split-thickness skin
graft. (a,b) Preoperative wound illustrates exposed tendon and periosteum. (c,d) Healthy granulation tissue over all structures following treatment
with negative pressure wound therapy. (e,f) Split-thickness skin graft coverage of wound. (g,h) Postoperative appearance.
Fig. 31.12 Traumatic foot injury with exposed bone managed with a local transposition flap and skin graft. (a) Preoperative appearance. (b) Exposed
bone following irrigation and debridement. (c) Local flap used to cover the area of exposed bone. (d) Donor defect is covered with a skin graft.
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Fig. 31.13 Exposed hardware after tibial fracture managed with medial gastrocnemius flap and split-thickness skin graft. (a) Preoperative view shows
the reconstruction plate. (b) Following coverage of plate with the muscle flap. (c) Skin graft over exposed muscle.
Fig. 31.14 An arteriovenous malformation of the foot was managed with completed extirpation and reconstruction with a free tissue transfer. (a)
Preoperative appearance. (b) Following resection. (c) Inset of anterolateral thigh free flap.
Lower Extremity
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Suggested Readings
Upton J, Tan C. Correction of constriction rings. J Hand Surg Am. 1991; 16
(5):947–953
Marsh DJ, Floyd D. Toe syndactyly revisited. J Plast Reconstr Aesthet Surg.
2011; 64(4):535–540
Hassanein AH, Rogers GF, Greene AK. Management of challenging congenital
melanocytic nevi: outcomes study of serial excision. J Pediatr Surg. 2015; 50
(4):613–616
Maclellan RA, Greene AK. Lymphedema. Semin Pediatr Surg. 2014; 23
(4):191–197
Greene AK, Maclellan RA. Operative treatment of lymphedema using suction-
assisted lipectomy. Ann Plast Surg. 2016; 77(3):337–340
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V
Part V
Upper Extremity
32 Embryology and Classification of Hand
Di erences

304
33 Disorders of Failure of Formation in the
Upper Limb

309
34 Thumb Hypoplasia

315
35 Syndactyly

325
36 Polydactyly

332
37 Macrodactyly

340
38 Brachial Plexus Palsies

343
39 Pediatric Hand Trauma

372

32 Embryology and Classification of Hand Di erences
Bran Sivakumar and Gill Smith
Sum m ary
Congenital hand di erences arise from genetic or environmen-
tal influences on the fetus during development. Embryogenesis
of the upper limb occurs between the fourth and eighth weeks
of gestation. Normal limb development requires a time-
dependent regulated sequence of transcription factors and
growth factors. It is best considered by simplification into the
three axes of development: proximodistal, anteroposterior, and
dorsoventral. Dysmorphology can result from disruption at any
stage during upper limb development and involve any struc-
tures. The International Federation of Societies for Surgery of
the Hand morphologically based classification of congenital
hand di erences predated current knowledge of etiology and
embryological development. The Oberg–Manske–Tonkin classi-
fication attempts to incorporate this to allow clinicians and
developmental biologists to communicate in a common lan-
guage. It o ers a framework for conveying the etiology of the
anomaly while remaining flexible to new developments.
Keywords: embryology, OMT, Oberg–Manske–Tonkin, hand,
limb bud, development, dysmorphology
32.1 Introduction
The incidence of upper limb anomalies is approximately 1 in
450 live births based on United Kingdom data. If one anomaly is
identified, there is also an increased likelihood of a further
non–upper limb anomaly. There is huge variety in the severity
of the appearance and the functional deficit associated with a
congenital hand di erence with many upper limb malforma-
tions resulting in relatively little disability due to adaptive strat-
egies. The range of congenital anomalies is vast, ranging from a
barely discernible mild thumb hypoplasia to complete agenesis.
Management of the patient requires accurate assessment and
diagnosis, clear communication with the family and child, and
may require therapy or surgical intervention. To Properly assess
such patients, a sound understanding of the pathogenesis of the
anomaly, and thus of normal upper limb embryology, is required.
In this chapter, we will discuss normal embryology and develop-
ment of the upper limb. We will then relate this to the stages
during which anomalies can develop, and finally the accepted
framework for classification of such congenital anomalies.
32.2 Early Embryology
The zygote undergoes cleavage during the first week of devel-
opment to produce a blastocyst, with an inner embryoblast and
an outer trophoblast. In week 2, the dorsoventral (DV) axis of
the embryo is established, with splitting of the embryoblast
into the primary ectoderm and primary endoderm. In the third
week, the primitive streak arises at the caudal end of the bila-
minar germ disc, establishing the longitudinal axis of the
embryo. The primitive node forms at the cranial end of the
primitive streak and connects to the notochord. The notochord
process is a mesodermal midline structure that induces the
development of the neural plate in the ectoderm.
Gastrulation begins in the third week. During this process,
the definitive endoderm, ectoderm, and mesoderm are formed,
converting the embryo into a trilaminar germ disc. The primi-
tive streak regresses, during which mesodermal cells on either
side of the notochord form the somatic mesoderm. These later
di erentiate into the axial skeleton, voluntary musculature, and
part of the skin dermis. A less pronounced lateral plate meso-
derm forms and splits into a ventral layer associated with the
endoderm, which forms the mesothelial covering of the viscera
and heart, and a dorsal layer associated with the ectoderm,
which forms the body wall lining and dermis.
32.3 Limb Bud Development
Limb bud development occurs between the fourth and eighth
weeks of embryonal development, with a later prolonged
growth phase after formation. The notochord expresses sonic
hedgehog (SHH) between days 21 and 22, which regulates the
initiation of the limb bud. The limb bud is an outgrowth of
somatic mesoderm and lateral plate mesoderm into the overly-
ing ectoderm, which forms an outer ectodermal “cap.” The
upper limb buds are first noted on the lateral body wall 24 days
after fertilization in the lower cervical region, at the level of C5–
C8. At 26 days, a ridge of bulging ectoderm develops on the ven-
tromedial border of the limb bud, termed the apical ectoderm
ridge (AER). Underlying this is a layer of undi erentiated mes-
enchymal cells termed the progress zone (PZ). Both are impor-
tant in ensuring proximodistal (PD) outgrowth of the limb, via
messenger proteins.
The human upper limb bud can be divided developmentally
into four main zones: the stylopod, the zeugopod, the mesopod,
and the autopod, which correspond approximately to the arm,
forearm, wrist, and hand, respectively. Positional information
regarding cell destination along the PD axis is conferred based
on the length of time spent within the PZ. Cells exiting the PZ
early are destined to form more proximal structures such as the
humerus, while those with a longer residence develop into the
more distal structures of the limb. Furthermore, each set of cells
exiting the PZ di erentiate and express di erent growth fac-
tors: the future stylopod expresses MEIS-1, the zeugopod cells
express OXA11 and HOXD9, mesopod cells express HOXA1, and
the autopod cells express HOXA13 and HOXD10–13.
32.3.1 Axes of Development
Limb growth and di erentiation progress along three axes: PD,
anteroposterior (AP), and DV. The PD axis refers to elongation of
the limb, the AP axis defines radioulnar or preaxial and postax-
ial orientation, and the DV axis provides dorsal and palmar ori-
entation. Development and di erentiation of each axis is
controlled by a separate signaling center. The AP axis is defined
first, followed by the DV axis, and then the PD axis. The PD axis
is controlled by the AER. It secretes WNT3 and fibroblast
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growth factors (FGFs) including FGF-2, FGF-4, and FGF-8. This
provides molecular control for the AER and for the di erentia-
tion and limb outgrowth through maintenance of FGF10
expression in the underlying mesoderm. This FGF10 expression
sustains proliferation of the PZ mesodermal cells, which in turn
are influenced by signaling centers to determine their fate. To
maintain PD growth, combined expression of WNT and FGF is
required.
AP axis development is controlled by the zone of polarizing
activity (ZPA) in the posterior limb mesoderm. The ZPA expands
limb width and promotes development of the posterior (ulnar)
aspect of the limb through expression of SHH at the distal pos-
terior border of the AER. The AER and ZPA form a reciprocal
feedback loop to maintain SHH expression and therefore AP
outgrowth.
DV axis growth is regulated by the secretion of WNT7A
within the dorsal ectoderm. This induces the Lim homeodo-
main transcription factor LMX1B, which dorsalizes the underly-
ing limb mesoderm. The ventral ectoderm secretes EN1 and
LMX1. WNT7A has also been shown to maintain secretion of
SHH (which influences many proteins) from the ZPA, thus link-
ing outgrowth in all three axes.
Signaling centers coordinate control of downstream targets
involved in development of the bony skeleton, vessels, muscles,
and nerves of the upper limb. These can involve both common
and asymmetric molecular pathways. For example, short-stature
homeobox 2 (SHOX2) is upregulated in the proximal perichon-
drium to promote humeral elongation. SHOX, in comparison,
is induced in the forearm perichondrium to regulate radioulnar
elongation. Appropriate and systematic induction of down-
stream pathways through coordinated action at multiple signal-
ing centers is essential in normal limb axis di erentiation.
32.4 Skeletal Di erentiation
At day 32, a hand plate is formed. All bones of the upper limb,
except the distal part of the phalanges, form as mesenchymal
condensations along the long axis of the limb during week 5.
They undergo endochondral ossification in response to growth
factors including FGFs, transforming growth factor beta (TGF-
β), bone morphogenic proteins (BMP), Indian hedgehog (IHH),
retinoids, and parathyroid hormone–related peptide (PTHrP).
Chondrification occurs in a proximal to distal direction, and
initially results in deposition of cartilage around the entire
axis mesenchymal condensation, termed the perichondrium. A
cartilaginous model of each bone is created, termed an anlage.
Further chondrification is limited to the anlage of each endo-
chondral bone. The mesenchyme in the interzones, which con-
stitutes the sites of future joints, di erentiates into fibrous
connective tissue. Chondrification of each anlage is followed by
ossification. This commences at the primary ossification center.
Mesenchymal cells in the perichondrium di erentiate into
osteoblasts in response to TGF-β and secrete a mineralized bone
matrix termed a primary bone collar around the circumference
of the bone. This collar thickens as osteoblasts continue to dif-
ferentiate in progressively more peripheral layers of the peri-
chondrium. Osteoclastic activity facilitates bone remodeling. In
the seventh week, the upper limb rotates so that the hands lie
anteriorly and the elbows posteriorly.
Formation of the distal portion of the distal phalanges is dif-
ferent, by intramembranous ossification. This means they form
directly from condensations of mesenchymal cells without the
formation of cartilage intermediary.
Joints develop through repression of chondrogenesis at spe-
cific sites of future joints. At these zones, the wingless proteins
WTN4 and WTN14 are expressed. The growth factor cartilage-
derived morphogenetic protein 1 (CDMP1) is also expressed at
these zones to repress chondrogenesis.
By birth, the limb diaphyses are completely ossified, but the
epiphyses remain cartilaginous. Secondary ossification centers
develop in these epiphyses and ossify. The persisting physis that
lies between the epiphysis and metaphysis allows diaphyseal
lengthening (growth).
32.5 Soft-Tissue Di erentiation
Muscle fibers develop in the upper limb bud by the seventh
week after fertilization, demonstrating migration and di eren-
tiation from superficial to deep and from proximal to distal.
Innervation of the limb follows myocyte migration. SHH expres-
sion from the notochord induces motor neuron di erentiation,
while HOX transcription factors expressed in the spinal cord
are thought to organize upper limb motor fibers into the lateral
motor column and convey axon-targeting information to partic-
ular muscle groups.
The first axial vessel, the marginal vein, appears in the fifth
week of development. Lymphatics develop to follow the veins.
The arterial system, in contrast, is not seen until the 33rd day
after fertilization. The brachial artery gives rise to the inteross-
eous and median arteries. The median artery is the primary
blood supply to the hand, and eventually gives rise to the ulnar
and radial arteries. At this stage, the median artery usually
regresses and supplies the median nerve alone.
The digital rays are initially syndactylized in utero. Hand
plate formation is influenced by SHH and HOX transcription
factors and BMP to create a posterior-to-anterior gradient. This
allows interdigital signaling centers and digital anlagen to be
established. The BMP gradient maps digit and interdigital fates
on the hand plate and represses the AER. Digit separation
occurs between the seventh and eighth weeks. Separation
occurs by apoptosis at the interdigital mesenchyme under the
influence of transcription factors including HOXD9, HOXD11,
and HOXD13, progressing from distal to proximal.
At birth, despite a fully formed limb, myelination of the
nerves is still incomplete.
32.6 Classification Systems
Congenital hand di erences have traditionally been classified
based on appearance. However, such descriptive terminology
does not enlighten the surgeon regarding etiology, surgical
approach and/or treatment, or overall prognosis. Dysmorphol-
ogy can result from disruption at any time during the initial for-
mative or later outgrow th stage of upper limb development.
32.6.1 Swanson Classification
The Swanson classification, first described in 1964, is based
upon morphology. Categories include failure of formation,
Embryology and Classification of Hand Di erences
305

failure of di erentiation, duplication, overgrow th, under-
growth, constriction band syndrome, and generalized skeletal
abnormalities. While its simplicity made it practical to use, as
the understanding of the genetic and embryological basis of
dysmorphology increased, a revised classification system taking
these new developments into account was suggested.
32.6.2 Oberg–Manske–Tonkin
Classification
The Oberg–Manske–Tonkin (OMT) classification (Box 32.1), first
proposed in 2010, is based on the developmental biological and
genetic basis of congenital limb anomalies rather than a purely
descriptive framework. It separates malformations from defor-
mations and dysplasias, and relates the diagnosis to the limb
axis of development involved and the a ected zone of the limb.
Using such terminology allows each congenital condition to
retain a surgical description and o ers a framework for convey-
ing the etiology of the anomaly while concomitantly remaining
flexible to new developments and conditions. It also means that
within the framework, if there are multiple anomalies (as found
in syndromic presentations, e.g.), the condition may be classi-
fied under multiple diagnoses including both the syndrome and
the upper limb anomalies. This is documented from most to
least prominent, and allows documentation of all dysmorphic
features, which may allow further identification of patterns of
anomalies.
Box 32.1 Oberg–Manske–Tonkin Classification of
Congenital Hand and Upper Limb Anomalies
Malformations
Failure of axis formation/di erentiation: entire upper limb
1. Proximodistal axis
a) Brachymelia with brachydactyly
b) Symbrachydactyly
1. Poland syndrome
2. Whole limb excluding Poland syndrome
c) Transverse deficiency
1. Amelia
2. Clavicular/scapular
3. Humeral
4. Forearm
5. Wrist (carpals absent/at level of proximal carpal row/at
level of distal carpals) (with forearm/arm involvement)
6. Metacarpal (with forearm/arm involvement)
7. Phalangeal (proximal/middle/distal) (with forearm/
arm involvement)
d) Intersegmental deficiency
1. Proximal (humeral—rhizomelic)
2. Distal (forearm—mesomelic)
3. Total (phocomelia)
e) Whole limb duplication/triplication
2. Radioulnar (anteroposterior) axis
a) Radial longitudinal deficiency—thumb hypoplasia (with
proximal thumb involvement)
b) Ulnar longitudinal deficiency
c) Ulnar dimelia
d) Radioulnar synostosis
e) Congenital dislocation of the radial head
f) Humeroradial synostosis—elbow ankyloses
3. Dorsoventral axis
a) Ventral dimelia
1. Furhamm/Al-Awadi/Raas–Rothschild syndromes
2. Nail–patella syndrome
b) Absent/hypoplastic extensor/flexor muscles
4. Unspecified axis
a) Shoulder
1. Undescended (Sprengel)
2. Abnormal shoulder muscles
3. Not otherwise specified
b) Arthrogryposis
Abnormal axis formation/di erentiation: hand plate
1. Proximodistal axis
a) Brachydactyly (no forearm/arm involvement)
b) Symbrachydactyly (no forearm/arm involvement)
c) Transverse deficiency (no forearm/arm involvement)
1. Wrist (carpals absent/at level of proximal carpal row/at
level of distal carpals)
2. Metacarpal
3. Phalangeal (proximal/middle/distal)
2. Radioulnar (anteroposterior) axis
a) Radial deficiency (thumb—no forearm/arm involvement)
b) Ulnar deficiency (no forearm/arm involvement)
3. iii Radial polydactyly
a) Triphalangeal thumb
b) Ulnar dimelia (mirror hand—no forearm/arm
involvement)
c) Ulnar polydactyly
4. Dorsoventral axis
a) Dorsal dimelia (palmar nail)
b) Ventral dimelia (including hypoplastic/aplastic nail)
5. Unspecified axis
a) Soft tissue
1. Syndactyly
2. Camptodactyly
3. Thumb in palm deformity
4. Distal arthrogryposis
b) Skeletal deficiency
1. Clinodactyly
2. Kirner’s deformity
3. Synostosis/symphalangism (carpal/metacarpal/
phalangeal)
c) Complex
1. Complex syndactyly
2. Synpolydactyly—central
3. Cleft hand
4. Apert hand
5. Not otherwise specified
Deformations
Constriction ring sequence
Trigger digits
Not otherwise specified
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Dysplasias
Hypertrophy
1. Whole limb
a) Hemihypertrophy
b) Aberrant flexor/extensor/intrinsic muscles
2. Partial limb
a) Macrodactyly
b) Aberrant intrinsic muscles of hand
Tumorous conditions
1. Vascular
a) Hemangioma
b) Malformation
c) Others
2. Neurological
a) Neurofibromatosis
b) Others
3. Connective tissue
a) Juvenile aponeurotic fibroma
b) Infantile digital fibroma
c) Others
4. Skeletal
a) Osteochondromatosis
b) Enchondromatosis
c) Fibrous dysplasia
d) Epiphyseal abnormalities
e) Others
Syndromes
Specified
1. Acrofacial dysostosis 1 (Nager type)
2. Apert
3. Al-Awadi/Raas–Rothschild/Schinzel phocomelia
4. Baller–Gerold
5. Bardet–Biedl carpenter
6. Catel–Manzke
7. Constriction band (amniotic band sequence)
8. Cornelia de Lange (types 1–5)
9. Crouzon
10. Down
11. Ectrodactyly-ectodermal dysplasia-clefting
12. Fanconi pancytopenia
13. Fuhrmann
14. Goltz
15. Gorlin
16. Greig cephalopolysyndactyly
17. Hajdu–Cheney
18. Hemifacial microsomia (Goldenhar syndrome)
19. Holt–Oram
20. Lacrimoauriculodentodigital (Levy–Hollister)
21. Larsen
22. Leri–Weill dyschondrosteosis
23. Moebius sequence
24. Multiple synostoses
25. Nail–patella
26. Noonan
27. Oculodentodigital dysplasia
28. Orofacial digital
29. Otopalatal digital
30. Pallister–Hall
31. Pfei er
32. Poland
33. Proteus
34. Roberts—SC phocomelia
35. Rothmund–Thomson
36. Rubinstein–Taybi
37. Saethre–Chotzen
38. Thrombocytopenia absent radius
39. Townes–Brock
40. Trichorhinophalangeal (types 1–3)
41. Ulnar—mammary
42. VACTERL syndrome association
Others
Abbreviation: VACTERL syndrome, vertebral anomalies, anal
atresia, cardiac abnormalities, tracheoesophageal fistula, renal
agenesis, and limb defects.
Note: The specified syndromes detailed in the table are
those considered most relevant based on the latest OMT
revised classification and IFSSH publications. However, many
other syndromes have a limb dysmorphology component and
are categorized under “B. Others.”
As already alluded to, the OMT classification uses dysmorphol-
ogy terminology to incorporate etiology and developmental
biology concepts into the framework of classification. These
terms are malformation, deformation, and dysplasia. A malfor-
mation is an abnormal formation of a body part. Deformation
refers to an insult occurring after normal formation. A dysplasia
is an abnormality in size, shape, and organization of cells within
a tissue. Separating conditions based on whether they result
from a malformation, deformation or dysplasia provide a solid
basis for etiological classification. Malformations are further
subdivided according to the predominantly a ected axis of
development, and the zone of the limb involved. The use of dys-
morphology terminology allows this framework the capacity to
be adapted and refined as our understanding of limb develop-
ment increases, as demonstrated by its revisions and extensions
since initial publication.
In 2014, the International Federation of Societies for Surgery
of the Hand (IFSSH) Scientific Committee on Congenital Condi-
tions recommended adoption of the OMT classification over the
Swanson classification. This is with the reservation that the
classification would be reviewed, once in common use, to reas-
sess its utility. Indeed, it has already been extended with sev-
eral modifications since its inception. It remains to be seen as to
its applicability in everyday clinic situations or whether its use-
fulness is more widespread within the research forum. Cur-
rently, neither the Swanson nor the OMT classification
determines or suggests surgical management, but if future
developments include the use of pre-implantation gene modifi-
cation techniques, this may change.
Embryology and Classification of Hand Di erences
307

32.7 Disruptions to Axis
Formation/Di erentiation
Understanding of how developmental disruption and interrup-
tion of signaling pathways lead to specific hand di erences is
continually improving, so just a few examples are included here
since greater detail is to be incorporated within subsequent
chapters.
Intersegmental phocomelias have been associated with SHOX
and SHOX2 with abnormalities in PD outgrowth. AP deficien-
cies have been noted with reduced FGF function, resulting in a
range of phenotypes including Apert syndrome. Progressive
loss of SHH expression or targeted temporal loss of SHH signal-
ing during development generates a spectrum of ulnar longitu-
dinal deficiencies. When associated with reduced FGF
expression through an interrupted SHH-FGF loop, this may
result in radial deficiencies, particularly involving the thumb,
which explains why most ulnar longitudinal deficiencies are
associated with both preaxial and postaxial deficiencies within
the hand plate. Brachydactyly type B1 has been associated with
a mutated receptor tyrosine kinase (ROR2) and WNTsignaling.
Reduction or loss of WNT7A or LMX1B expression in the
dorsal mesoderm results in impaired dorsalization, with abnor-
mal elbow and nail formation such as seen in nail–patella
syndrome.
32.7.1 Soft-Tissue Deficiencies
Ectopic overexpression of BMP inhibitors in the limb mesen-
chyme and persistent or overexpressed FGF in the AER can
result in inhibited interdigital apoptosis with resultant syndac-
tyly. Mutations in BMP inhibitors are associated with syndac-
tyly, polydactyly, and joint synostoses. GLI3 and HOXD13 gene
mutations can cause these anomalies, but the pattern depends
on which specific signals are interrupted so that identical geno-
types may produce quite significantly di erent phenotypical
appearances and hence the need for a classification based on
etiology and pathogenesis rather than morphology.
32.8 Conclusion
The embryogenesis of the upper limb relies on a relatively com-
plex and closely regulated sequence of transcription factors and
growth factors to ensure normal development. Limb embryo-
genesis is best thought of in terms of three axes of develop-
ment: PD, AP, and DV. Appreciation of normal embryology
allows a better understanding of the underlying etiology of con-
genital limb anomalies, and therefore can aid an appreciation of
the future management, including operative approaches, and
prognosis. The OMT classification takes these aspects into con-
sideration and o ers a logical framework for this wide spec-
trum of anomalies. While conditions may require classification
under multiple diagnoses including both the syndrome and the
upper limb anomalies, this allows comprehensive documenta-
tion of all anomalies. As the genetic basis of upper limb embry-
ology is further elucidated, review and further streamlining of
this framework may be achieved in the future.
32.9 Key Points
The upper limb develops between the fourth and eighth weeks
after fertilization from the x and y.
● Development should be considered in terms of the DV, AP,
and PD axes.
● The OMT classification of congenital hand and upper limb
anomalies incorporates our understanding of etiology, molec-
ular genetics, and developmental biology to help organize the
main groups and subgroups of congenital abnormalities and
syndromes.
● Classification can be based on the broad themes of malforma-
tions, deformations, and dysplasias, with cross-referencing for
abnormalities with an associated syndromic component.
Suggested Readings
Tonkin MA, Tolerton SK, Quick TJ, et al. Classification of congenital anomalies
of the hand and upper limb: development and assessment of a new system. J
Hand Surg Am. 2013; 38(9):1845–1853
IFSSH Scientific Committee on Congenital Conditions Report. February 2014
Sammer DM, Chung KC. Congenital hand di erences: embryology and classi-
fication. Hand Clin. 2009; 25(2):151–156
Al-Qattan MM, Kozin SH. Update on embryology of the upper limb. J Hand
Surg Am. 2013; 38(9):1835–1844
Schoenwolf GC, Bleyl SB, Brauer PR, Francis-West PH. Larsen’s Human Embry-
ology. 5th ed. Philadelphia PA: Elsevier Saunders;2008
Ekblom AG, Laurell T, Arner M. Epidemiology of congenital upper limb
anomalies in Stockholm, Sweden, 1997 to 2007: application of the Oberg,
Manske, and Tonkin classification. J Hand Surg Am. 2014; 39(2):237–248
Upper Extremity
308

33 Disorders of Failure of Formation in the Upper Limb
Dariush Nikkhah and Bran Sivakumar
Sum m ary
Disorders of failure of formation of the upper limb include:
transverse arrest, radial and ulnar longitudinal deficiency, and
central ray deficiency. The conditions are usually sporadic, but
may be associated with several syndromes. Management is
based on the type and severity of the deformity.
Keywords: longitudinal deficiency, transverse arrest, central ray
deficiency, cleft hand
33.1 Transverse Deficiencies
Congenital transverse arrest is a rare abnormality that com-
monly occurs at the level of the wrist or proximal forearm.
Transverse arrest is usually sporadic without a genetic inheri-
tance; its incidence has been reported as 6% of all congenital
upper limb deficiencies.
33.1.1 Diagnosis of Transverse Arrest
Transverse arrest can occur at multiple levels, from the humeral
down to the metacarpal level of the upper limb. Transverse
arrest above the elbow is rare. The distal stump is usually
rounded and often contains some nubbinlike hand/digital rem-
nants ( Fig. 33.1). Areas of dimpling are sometimes present
where the skin is tethered to the end of hypoplastic skeletal
structures. The condition is most often unilateral and more
often a ects the left side. It has a 3:2 female predominance.
33.1.2 Treatment of Transverse Arrest
Regular detailed assessments of function and psychosocial
well-being are required prior to embarking on any treatment
given these children often adapt remarkably well to their limb
di erences.
The m anagement of transverse arrest varies according to
the level of involvem ent. In above-elbow transverse defi-
ciencies, the main treatm ent options involve prostheses.
However, in unilateral cases, compliance to prostheses can
be poor in part due to a lack of sensory feedback from the
devices. However, a variety of prostheses are available for
trial and range from static to dynam ic, som e of w hich can
be controlled by rem aining skeletal structures or myoelectric
impulses.
Surgical options for proximal transverse deficiencies include
the removal of excess functionless parts such as digital nubbins
or stump revision to facilitate prosthetic fitting. At the forearm
level, few surgical options exist; one historic option described is
the Krukenberg procedure. The radius and ulna are separated
to create a basic prehensile pattern between the two bones.
This procedure is not recommended because the cosmetic
appearance is very poor and the separation of the forearm
bones can prevent the e ective use of prostheses.
Vascularized second-toe transfer is an option in children with
carpal and metacarpal hands. In children with carpal hands,
second toes can be transferred to the positions of the first and
fifth digits. In the absence of digits, the transfer of two second
toes in this way allows the creation of a basic prehension pat-
tern. This tends to be more e ective in cases where the child is
able to cup their palm.
Distal cases of transverse arrest are often referred to as sym-
brachydactyly. Treatment options in these cases include web
deepening, metacarpal transposition, distraction lengthening of
existing skeletal parts, vascularized second-toe transfers, and
nonvascularized toe phalangeal transfers. Preservation of the
phalangeal periosteum and minimization of tension within
the recipient soft-tissue envelopes in the hypoplastic digits are
key to long-term survival of nonvascularized toe phalangeal
transfers.
33.1.3 Outcomes and Complications
Careful assessment of cases is vital to prevent unnecessary in-
tervention given these children adapt remarkably well. All via-
ble treatment options must be explained to the child and
family. The unpredictably of prosthesis use in unilateral cases
must be emphasized. In more distal cases, at the carpal and
metacarpal level, the creation or upgrade of a prehension pat-
tern can significantly improve hand functionality and increase a
child’s bimanual repertoire.
Donor site issues appear to be common in cases of nonvascu-
larized toe phalangeal transfers particularly when children
reach their adolescent growth spurt. However, techniques to
minimize these complications such as the use of replacement
iliac crest bone grafts have been shown to be e ective.
Distal transverse deficiency is often an ideal indication for
free vascularized toe transfer. Excellent outcomes have been
seen in terms of function, cosmesis, and psychosocial well-
being with little donor site morbidity in large series with signif-
icant long-term follow-up.
Fig. 33.1 Transverse arrest at proximal forearm level. Rudimentary
hand remnants visible at tip of rounded stump.
Disorders of Failure of Formation in the Upper Limb
309

33.2 Longitudinal Deficiencies
33.2.1 Radial Longitudinal Deficiency
Radial Longitudinal Deficiency (RLD) represents a spectrum of
anomalies, which can involve the entire preaxial side of the
upper limb. In the past, a variety of terms have been used to
refer to the condition, including radial club hand, radial hypo-
plasia, and meromelia. RLD is the most common out of the lon-
gitudinal deficiencies and occurs in 1/30,000 cases. Unilateral
cases are more common with a R:L predilection of 2:1. Genetic
and environmental factors such as thalidomide have been
shown to play a role in RLD.
RLD can be linked with other anomalies and syndromes, and
therefore screening is essential (Box 33.1). Bilateral cases of RLD
are more likely to have a syndromic association.
Box 33.1 Cardiac, Renal, and Hematological
Syndromes Associated with Radial
Longitudinal Deficiency
● Holt–Oram syndrome: vertebral anomalies, anal atresia, car-
diac abnormalities, tracheoesophageal fistula, renal agenesis,
and limb defects
● VACTERL syndrome: vertebral anomalies, anal atresia, cardiac
abnormalities, tracheoesophageal fistula, renal agenesis, and
limb defects
● Fanconi syndrome: autosomal recessive condition with aplas-
tic anemia
● TAR: autosomal recessive condition with thrombocytopenia
and absent radius
33.2.2 Diagnosis of Radial Longitudinal
Deficiency
As a result of skeletal deficiency and soft-tissue abnormalities
in RLD, the hand adopts a radially deviated and abnormally
flexed posture at the end of a hypoplastic forearm (Fig. 33.2).
Complete assessment of the upper limb is important given that
abnormalities can occur along its entire length from the
shoulder to the radial side of the hand. The upper arm may be
shorter with distal humeral epiphyseal involvement and in
some cases a sti elbow. The forearm is shorter to varying
degrees and the severity of skeletal hypoplasia is classified into
four grades based on radiographic assessment according to the
system described by Bayne and Klug (Table 33.1). Type 1 rep-
resents a short radius and type 2 a hypoplastic radius with
involvement of the proximal and distal epiphyses. In type 3, the
distal part of the radius is replaced by a tethering fibrous anlage
and in type 4 there is complete radial aplasia. The main factors
contributing to radial deviation are hypoplasia and mal-inser-
tion of a combined muscle mass of FCR, ECRB, ECRL, and BR,
radial displacement of the median nerve, tightened deep fascia,
and in some type 3 cases a radial anlage. The forearm–wrist
articulation is often unstable and nonfunctional with hypopla-
sia of the radial side of the carpus. Within the hand, the thumb
is hypoplastic or most often absent. The index and middle fin-
gers are also a ected with varying degrees of hypoplasia and
sti ness.
33.2.3 Associated Syndromes
There are a number of syndromes linked to RLD; these include
VACTERL (vertebral anomalies, anal atresia, cardiac abnormal-
ities, tracheoesophageal fistula, renal agenesis, and limb
defects) association, TAR (thrombocytopenia and absent radius)
syndrome, and Holt–Oram and Fanconi anemia (Box 33.1).
These syndromes, which occur in approximately one-third of
patients with RLD, confer a poorer prognosis and require early
detection and treatment. Complete assessment of the limbs,
cardiac, renal, spinal, and hematological systems must be
carried out.
33.2.4 Treatment of Radial Longitudinal
Deficiency
The main aims of treatment in RLD are to create stable align-
ment of the hand and carpus on the end of the ulna, maximize
function, and optimize growth potential.
Treatment begins with a regime of regular stretching and
splinting under the guidance of a hand therapist. Physiotherapy
aims to address the shortened deviating soft-tissue structures
on the radial side of the wrist and at the same time maintain
digit mobility and strength.
Subsequent surgical intervention depends on the severity
of the hypoplasia and the child’s overall functionality. In the
Fig. 33.2 Image of patient with radial longitudinal deficiency, dem-
onstrating short limb with stiff elbow and radial deviation and flexed
posture of the wrist joint. Note absence of the thumb and widening of
the second webspace.
Table 33.1 Bayne classification of radial longitudinal deficiency
GR

Radial longitudinal deficiency
I

Short distal radius
II

Hypoplastic radius
III

Partial absence of radius
IV

Total absence of radius
Source: Bayne and Klug (1987).
Upper Extremity
310

majority of type 1 cases where the wrist is stable and easily cor-
rected to neutral, no intervention is required. However, if a ten-
dency for radial deviation remains, a tendon transfer of the
tight combined dorsoradial muscle mass to the ulnar side of the
carpus may be required. Type 2 hypoplastic RLD cases are more
challenging to treat. Distraction lengthening of a small radius
can be e ective but often needs repeating to keep up with
growth. Type 3 and 4 cases are best dealt with by soft-tissue
distraction of the short radial deforming structures followed by
a wrist centralization/radicalization procedure to create a stable
ulna–carpal equilibrium.
33.2.5 Soft-Tissue Distraction
Kessler first described the use of gradual distraction lengthen-
ing of soft tissues in RLD. This technique facilitates definitive
wrist correction and minimizes the need for skeletal shorten-
ing. Since Kessler’s first description, a range of di erent distrac-
tion devices have been successfully applied to cases of RLD
including uniplanar and ring fixator systems. Our preference is
a uniplanar device with a central coaxial hinge placed on the
radial side of the limb and secured by pin fixation into the ulnar
proximally and into the radial metacarpals distally (Fig. 33.3).
Distraction is performed at approximately 0.5 to 1 mm a day for
6 to 8 weeks and stopped once the third metacarpal base is
aligned with the distal ulna in preparation for the wrist correc-
tive procedure.
33.2.6 Wrist Correction in Radial
Longitudinal Deficiency
Wrist correction is achieved through either a centralization or a
radicalization procedure. Centralization involves fixation of the
distal ulna in line with the third metacarpal in a central slot cre-
ated in the proximal carpal row. As a result of the fusion to the
proximal row, centralization results in more stability but less
wrist motion and shorter limb when compared to radicaliza-
tion. Radicalization involves stabilization of the carpus of the
ulna in line with the second metacarpal without a carpal slot.
Both procedures require transfer of the dorsoradial muscle
mass into the base of the fifth metacarpal to convert a deform-
ing radial force into corrective stabilizing dorso–ulnar one. A
radicalization is more dependent on the quality of this tendon
transfer for long-term stability. Both types of correction are
supported with longitudinal K-wire fixation for a period of 6 to
12 months.
33.2.7 Microvascular Reconstruction in
Radial Longitudinal Deficiency
An alternative to centralization/radicalization in RLD is recon-
struction of a stabilizing radial buttress using vascularized fib-
ula or metatarsophalangeal transfers. This technique is gaining
popularity in a number of units around the world, and long-
term follow-up of this approach is ongoing.
33.2.8 Outcomes and Complications of
Radial Longitudinal Deficiency
Soft-tissue distraction has revolutionized treatment of RLD. It
has allowed the optimization of limb length, growth potential,
and wrist mobility (ulna–carpal) in type 3 and 4 cases.
A radicalization, although it preserves motion and length, is
inherently more unstable than a centralization and as a result is
more vulnerable to long-term recurrent radial deviation. There-
fore, we advocate a centralization in cases where the quality of
the dorsoradial muscle mass or ulna–carpal joint congruity
does not lend itself to the stable equilibrium required for a
radicalization.
A formal wrist arthrodesis is a salvage procedure for children
nearing skeletal maturity in cases of recurrent deviation and
resultant poor function despite treatment.
33.3 Central Ray Deficiency
Central longitudinal failure of formation (congenital limb defect
[CLD]) also known as cleft hand represents a spectrum of
deformities that involve hypoplasia or absence of the central
rays of the hand. Children with this condition typically function
well and have been described by Flatt as “a functional triumph
and social disaster.” Typical presentation includes the presence
of a “V”-shaped central cleft, malpositioning of adjacent rays
with narrowing of the first webspace ( Fig. 33.4). It is distinct
from symbrachydactyly, which typically presents with a broad
“U”-shaped cleft and bordering digital hypoplasia. CLD is an
autosomal dominant condition with variable expressivity. CLD
can occur in isolation, but the majority of patients present with
cleft hands and feet, a spectrum termed split hand (SH) and
split foot (SF) complex.
33.3.1 Diagnosis of Congenital Limb
Defect
Awide range of cleft hand morphology exists ranging from sim-
ple soft-tissue clefts without digital absence, through varying
degrees of central ray hypoplasia to complete suppression of all
bony elements of the hand except for the little finger. A number
of di erent classification systems exist to describe the range of
deficiencies seen in CLD, the most useful of which was put for-
ward by Manske in 1995. This system is based on the quality of
Fig. 33.3 Uniplanar soft-tissue distraction device in situ; it is fitted onto
the radial aspect of the limb.
Disorders of Failure of Formation in the Upper Limb
311

the first webspace and radial digits, and provides a better indi-
cation of likely function than classifications that examine the
central ray deficiency itself ( Table 33.2). The classification
ranges from grade 1 where there is no significant narrowing of
the first web, through worsening grades of first web narrowing,
syndactyly, and merging (grades 2–4) to complete absence of
the thumb and radial digits (grade 5). The classification system
also serves as a useful guide for treatment (Fig. 33.5).
33.4 Treatment of Cleft Hand
Close monitoring of patients with CLD is important given that
many children adapt well to a central deficiency and show no
significant functional impairment. However, some cleft hands
do require some functional optimization; for example, if the
index finger sits too close to the thumb, it may be bypassed in
pinch in preference for the ring finger. Transposition of the
index finger into the long finger position allows creation of a
wider first webspace and greater inclusion of the index finger
into grasp and pinch. Other major indications for operative in-
tervention include narrowing/syndactyly of the first webspace
and severe flexion contracture of the digits. Timing of surgery
varies according to functional need. Early intervention is advo-
cated in cases of first web syndactyly to prevent thumb–index
length discrepancy from a ecting grow th.
33.4.1 Surgical Techniques
A simple soft-tissue cleft can be closed with a small commissu-
ral flap, which allows the creation of a natural “U” shape within
the webspace. Within deeper clefts, a range of di erent techni-
ques utilizing local random pattern flaps of volar or dorsal
skin have been employed to resurface the newly widened first
webspace following transposition of a malpositioned index
finger. Problems of distal flap necrosis and subsequent web
Fig. 33.4 Image of patient with central longitu-
dinal deficiency. Note absence of distinct central
ray, merging of long and ring finger with
malposition of the index finger and narrowing of
the first webspace.
Fig. 33.5 Type 4 radial longitudinal deficiency with complete absence
of the radius and bowing of the ulna with no functional wrist joint. The
hand and carpus are radially deviated and there is complete absence of
the thumb.
Table 33.2 Manske first webspace classification of cleft hand
GR
Manske first webspace classification
I

Normal web: no treatment
IIB

Mildly narrowed web: four-flap Z-plasty
IIA

Severe narrowing: palmar- or dorsal-based flap
III

Syndactylized thumb: palmar or dorsal rotation flap
IV

Merged webspace: cleft deepening and rotational osteotomies
V

Absent web: microsurgical toe transfer
Upper Extremity
312

contracture have prompted evolution of these techniques away
from long random pattern flaps. Our preferred method is that
described by Upton in 2010 in which the volar and dorsal skin
are peeled back via a racket incision around the index finger
with straight-line extensions (between the glabrous and dorsal
skin) along the cleft and first webspace. The index finger is then
transposed, problematic aberrant anatomy addressed, and the
skin redraped to create a new broad first webspace and a natu-
ral second webspace contour with the help of a commissural
flap from the radial side of the ring finger (Fig. 33.6). The new
position for the index finger is held using K wires into the base
of the middle finger metacarpal remnant or distal carpal row.
Preservation of the adductor pollicis origin, if present, is impor-
tant in order to optimize key pinch. Reconstruction of the inter-
metacarpal ligament can be achieved through simple sutures
alone, circumferential sutures around adjacent metacarpals, or
through the union of adjacent A1 pulleys.
Adjacent severe flexion contractures of other digits can be
addressed along the principles outlined for camptodactyly
treatment.
33.4.2 Outcomes and Complications of
Cleft Hand Correction
Surgery must be carefully considered in CLD because function
should always take priority over aesthetics. Complications of
flap contracture within the webspaces have been reduced
through avoidance of long random pattern flaps. Long-term fol-
low-up in these cases is essential as issues can arise as a result
of di erential grow th between a ected and normal areas, for
example, between long index fingers and short and sometimes
contracted adjacent digits. Problems of progressive joint con-
tractures must be addressed early.
33.5 Ulnar Longitudinal Deficiency
Ulnar longitudinal deficiency (ULD), referred to in the past as
ulnar club hand, is the rarest of the longitudinal deficiencies (1–
7.4 per 100,000 births). As with RLD, it can a ect the entire
length of the upper limb. However, unlike in RLD, the wrist is
usually more stable and the elbow more severely a ected in
ulnar deficiencies. ULD is frequently associated with other mus-
culoskeletal abnormalities and sometimes linked to syndromes
a ecting the hematopoietic, gastrointestinal, genitourinary, and
cardiopulmonary systems.
33.5.1 Diagnosis of Ulnar Longitudinal
Deficiency
ULD is graded into four main types according to the Bayne clas-
sification. Grade 1 refers to a hypoplasia of the ulna. Grade 2 is
the most common and represents a partial aplasia of the ulna
with bowing of the radius and sometimes a dislocation of the
radial head. In grade 3, the ulna is entirely absent and there is
again significant bowing of the radius with a radial head dislo-
cation. Finally, in type 4, there is a radiohumeral synostosis
alongside complete aplasia of the ulna. More recently, patients
with an isolated ulnar-sided deficiency of the hand and digits in
the presence of a normal forearm have been referred to as hav-
ing a type 0 ULD. Patients tend to present with varying degrees
of ulna hypoplasia and forearm bowing (Fig. 33.7). In some
patients, this results in a “hand behind the back” posture, which
is particularly evident in grade 4 cases. The wrist deformities
seen in ULD are secondary to stunted growth of the ulnar side
of the distal radial epiphysis and in some cases a tethering
e ect of an ulna anlage. In the majority of cases, it is the hand
deformities that impact on patient function the most. The
severity of these hand abnormalities appears unrelated to the
degree of the forearm, elbow, and upper arm deficiency. Fur-
thermore, in over 50% of cases of ULD, there is an abnormality
a ecting the radial side of the hand, the functional significance
of which prompted the creation of a supplementary classifica-
tion by Manske examining the state of the thumb and first web-
space in ulnar deficiencies (Table 33.3).
33.6 Treatment in Ulnar
Longitudinal Deficiency
Conservative treatment involving splinting and stretching in
the first year of life can be helpful in some cases of ULD.
The majority of surgery in cases of ULD are focused on the
hand because this appears to hold the greatest functional bene-
fit. Commonly performed procedures include syndactyly
releases, rotational osteotomies to facilitate prehension, web-
space deepening in particular of the first webspace, thumb
reconstructions, and pollicizations.
With regard to the forearm in Bayne grades 2 and 3, there is
often a functional benefit from excision of the fibrous ulnar
anlage to prevent progressive deformity of the radius. If there is
significant radial deformity, the excision of the anlage can be
performed alongside a corrective osteotomy of the radius. In
some grade 3 and 4 cases, creation of a one-bone forearm from
the distal radius and proximal ulna allows for simultaneous sta-
bilization of the wrist and elbow, removal of an obstructive dis-
located radial head, and optimization of forearm length. It is
best performed in patients with radial head dislocation, fore-
arm instability, and marked limitation of elbow extension.
Fig. 33.6 Surgical correction of typical cleft hand using Upton
technique. Note the transposition of the index finger into the long
finger position with widening of the first webspace. A clinodactyly
correction in the ring finger has also been carried out.
Disorders of Failure of Formation in the Upper Limb
313

Surgery to the elbow is sometimes required in cases of grade
4 ULD where there is a radiohumeral synostosis and the limb
adopts a “behind the back” posture. In these cases, a de-rota-
tional osteotomy through the synostosis allows for a more func-
tional placement of the forearm and hand in front of the body.
33.6.1 Outcomes and Complications of
Ulnar Longitudinal Deficiency Surgery
There are few long-term studies looking at subjective and
objective outcomes in ULD most probably due to the rarity of
the condition. Humeral and radial osteotomy surgery is useful
to treat those children with poor spatial positioning of the limb.
However, in the majority of ULD patients, the greatest func-
tional gains are from surgery to the hand.
Minor complications include web creep after syndactyly
release and more major complications include delayed union,
malunion or nonunion, or failure to correct positional deform-
ities. Iatrogenic injury to the posterior interosseous nerve is a
risk in the creation of a one-bone forearm (Sénès and Catena
2012).
33.7 Key Points
● Transverse arrest often does not require surgical intervention
as children adapt well.
● RLD is associated with many coexisting syndromes and
patients should be screened for cardiac, hematological, and
renal abnormalities.
● Soft-tissue distraction has revolutionized the management of
RLD, reducing recurrence, optimizing growth potential, and
facilitating surgical wrist correction.
● Classically function is good within cleft hands, but aesthetics
can be poor.
● The majority of the surgery in ulnar longitudinal deficiency is
directed at the hand.
Suggested Readings
Kay SP, Wiberg M. Toe to hand transfer in children. Part 1: technical aspects. J
Hand Surg [Br]. 1996; 21(6):723–734
Upton J. Management of transverse and longitudinal deficiencies. In Mathes,
ed. The Hand and Upper Limb. 2nd ed. Philadelphia, PA: Saunders Elsevier;
2006:51–38
Bayne LG, Klug MS. Long-term review of the surgical treatment of radial defi-
ciencies. J Hand Surg Am. 1987; 12(2):169–179
Buck-Gramcko D. Radialization as a new treatment for radial club hand. J
Hand Surg Am. 1985; 10(6, Pt 2):964–968
Kessler I. Centralisation of the radial club hand by gradual distraction. J Hand
Surg [Br]. 1989; 14(1):37–42
de Jong JP, Moran SL, Vilkki SK. Changing paradigms in the treatment of radial
club hand: microvascular joint transfer for correction of radial deviation and
preservation of long-term growth. Clin Orthop Surg. 2012; 4(1):36–44
Manske PR, Halikis MN. Surgical classification of central deficiency according
to the thumb web. J Hand Surg Am. 1995; 20(4):687–697
Cole RJ, Manske PR. Classification of ulnar deficiency according to the thumb
and first web. J Hand Surg Am. 1997; 22(3):479–488
Sénès FM, Catena N. Correction of forearm deformities in congenital ulnar
club hand: one-bone forearm. J Hand Surg Am. 2012; 37(1):159–164
Bayne LG. Ulnar club hand—ulnar deficiency. In: Green DP, ed. Operative
Hand Surgery. New York: Churchill Livingstone; 1982
Fig. 33.7 Image of ulnar longitudinal deficiency
with typical shortened forearm appearance with
deficiency of ulnar digits. Note previous first web
widening scarring.
Table 33.3
GR

Manske classification of ulnar deficiency, 1997
I

Normal first web and thumb
II

Mild first web and thumb deficiency
III

Moderate to severe first web and thumb deficiency
IV

Absent thumb
Upper Extremity
314

34 Thumb Hypoplasia
Amir H. Taghinia and Joseph Upton
Sum m ary
Thumb hypoplasia can cause significant loss of function
because it is the most important digit of the hand. Most
patients require surgical intervention which is based on the
type of hypoplasia. Treatment ranges from first webspace wid-
ening to index finger pollicization.
Keywords: thumb, hypoplasia, classification, polliciation
34.1 Introduction
The thumb is the prime ray of the hand. Its size, position, mobi-
lity, and relationship to other digits is critical for function. In
the first few months of life, the thumb is adducted and flexed
within the palm. Large object grasp starts around 6 months of
age, and small object pinch starts around 9 months of age. By
this time, the first ray has gained independence from the palm
and by a year of age, it has become the most important ray of
the hand. In the young toddler, the thumb is used creatively and
independently to explore and manipulate the environment.
The thumb is considered hypoplastic if any portions of
the ray including bony or soft-tissue components are underde-
veloped or absent. Children with thumb hypoplasia can su er
from other associated conditions that a ect the heart, blood,
skeleton, and other systems. The widely accepted classification
system for thumb hypoplasia was initially proposed by Blauth
and later modified by Manske. This system is concise and prac-
tical as it guides surgical treatment (Fig. 34.1).
With the exception of mild hypoplasia, most patients with
thumb hypoplasia require surgical intervention. Treatment
ranges from simple procedures such as first webspace widening
to more complex procedures such as index finger pollicization.
Over the past 30 years, there have been refinements in surgical
techniques that improve both appearance and function. Recent
advances in outcome instruments hold promise for better func-
tional delineation of the impact of surgical interventions for
these conditions.
34.2 Diagnosis
Correct diagnosis starts with a thorough physical examination
and plain radiographs. Although it is di cult to accurately
assess ligament stability and active function in a newborn, an
accurate assessment of deficient anatomy is possible. Accord-
ingly, a preliminary diagnosis can be given early on and then
modified as the child grows. Once the child starts to use the
hand, a correct diagnosis is much easier to establish. Physical
examination and radiographs should guide classification of the
thumb using the Blauth system (Fig. 34.1).
34.2.1 Associated Conditions
It is critical for the hand surgeon to be aware of conditions that
are associated with thumb hypoplasia. Oftentimes—especially
in those with blood conditions—these children manifest radial
deficiency as their only physical di erence. Accordingly, the
hand surgeon can be instrumental in diagnosing associated
conditions. These conditions include, but are not limited to,
Fanconi anemia, Holt–Oram syndrome, and VACTERL (vertebral
anomalies, anal atresia, cardiac abnormalities, tracheoesopha-
geal fistula, renal agenesis, and limb defects) complex.
Type I: Mild Hypoplasia
In this mildest type of hypoplasia, the thumb is thinner and
shorter than normal. The joints show normal range of motion,
and flexion and extension creases are easily visible. There
may be slightly smaller thenar intrinsic muscles, mainly the
abductor pollicis and opponens pollicis; however, all of the
Fig. 34.1 Radiographical classification of thumb hypoplasia. Type I hypoplasia, the mildest severity, is not shown. The main distinguishing feature
between type IIIA and IIIB hypoplasia is the presence of a functional carpometacarpal joint.
Thumb Hypoplasia
315

intrinsic muscles are present. The joints are stable. The first
webspace deficiency may be slight to moderate.
Type II: Moderate Hypoplasia
In this type of hypoplasia (Fig. 34.2), the bones of the ray are
present but small. The radial carpal bones (trapezium and sca-
phoid) may be small and cause slight radial deviation of the hand.
The first webspace is narrow and the thumb adducted. The meta-
carpophalangeal (MP) joint collateral ligaments are lax and the
median-innervated thenar muscles are hypoplastic or absent.
There may be extrinsic flexor and/or extensor deficiencies and
these usually manifest by the lack of flexion or extension creases.
Type III: Severe Hypoplasia
The degree of thumb skeletal shortening and joint laxity is
much more severe in these hands. These thumbs have been div-
ided into subtypes A and B, based on the length of the
metacarpal and stability of the carpometacarpal (CMC) joint. In
type A (Fig. 34.3), the CMC joint is stable, the metacarpal is
narrow, and the child uses the thumb. In type B (Fig. 34.4),
the CMC joint is unstable, the metacarpal is incomplete, and the
child does not use the thumb. Type IIIA thumbs have severely
hypoplastic thenar muscles and usually lack an extrinsic flexor.
The collateral ligaments at the MP joint are lax and prevent sus-
tained large object grasp—children usually use the head of the
metacarpal for grasp. The extrinsic muscles insert abnormally
and conspire to act primarily as radial deviators and not as pri-
mary flexors or extensors. This is known as “pollex abductus.”
Many anatomical variations of this anomaly exist, but the func-
tional result is identical: when the extrinsic muscles activate,
the thumb radially deviates. Type IIIB thumbs share many of the
same characteristics as type IIIA thumbs with greater degree of
hypoplasia. In addition, the CMC joint is unstable in these
thumbs. Most children with these thumbs will not use the
thumb routinely; instead, they automatically use the index and
middle fingers.
Fig. 34.2 Type II thumb hypoplasia.
Upper Extremity
316

Type IV: Floating Thumb
The floating thumb (pouce flottant, French; pendeldaumen,
German) is only attached to the hand by a soft-tissue pedicle
that contains a neurovascular bundle (Fig. 34.5). There is no
metacarpal. The thumb has a rudimentary nail and one or two
small phalanges. It is functionless.
Type V: Aplasia
In this type of hypoplasia, the thumb is completely absent
(Fig. 34.6). The radial side of the hand is hypoplastic. There is
often an associated deficiency of the radius; and if so, there
may be concomitant hypoplasia or sti ness of the index finger.
If the index finger is normal, many patients will autopronate
the index finger and scissor-grasp with the middle finger. The
pulp of the index finger widens and the digit pronates, sitting
in a more abducted position and thus widening the intermeta-
carpal space.
Other Types: Five-Fingered Hand
In this type, the most radial digit looks and functions like a fin-
ger ( Fig. 34.7). It usually lies in the same plane as the ulnar
four digits and is nonopposable. Severe deficiency of the first
webspace is present. The metacarpal has a distal growth center
and the intrinsic muscles are those that typically motor a finger,
not a thumb.
Other Types: Radial Polydactyly
Many have observed that each partner of a radial polydactyly
thumb is hypoplastic to varying degrees. The ulnar partner
is less a ected. In these thumbs, opponensplasty is usually
not needed because the disposed radial partner usually
presents a strong intrinsic muscle. The webspace may need
widening in more proximal arborizations. Extra phalanges and
pollex abductus abnormalities should be recognized.
34.3 Nonoperative Treatment
Conservative treatment alone is advocated for the most minor
types of thumb hypoplasia. Splinting and stretching exercises
are most useful early on in infancy when the soft tissue is plia-
ble. In those patients who bypass a less functional thumb,
one can try to encourage use of the thumb by buddy taping
the index and middle fingers. This technique is useful early on
in patients who have had thumb reconstruction or even
pollicization.
Fig. 34.3 Type IIIA thumb hypoplasia.
Thumb Hypoplasia
317

Fig. 34.4 Type IIIB thumb hypoplasia.
Fig. 34.5 Type IV thumb hypoplasia.
Upper Extremity
318

34.4 Operative Treatment
In the milder forms of thumb hypoplasia (types II–IIIA), surgical
reconstruction addresses deficiencies in first webspace width,
MP joint stability, and opposition. Treatment is tailored to the
individual, depending on deficiencies in each of the aforemen-
tioned areas. In the more severe forms of hypoplasia (types IV
and V), index finger pollicization is the ideal reconstructive
procedure. There is some debate in the literature about the best
treatment of type IIIB thumbs. Although most authors recom-
mend index finger pollicization, a few advocate strongly for
reconstruction of the CMC joint using free vascularized meta-
tarsophalangeal joints.
Fig. 34.6 Type V thumb hypoplasia.
Fig. 34.7 A five-fingered hand.
Thumb Hypoplasia
319

The timing for surgical intervention is debatable. For recon-
struction of minor hypoplasia (types II–IIIA), most surgeons
intervene around 2 years of age or older. Opponensplasty and
ligament reconstruction is particularly di cult in a younger
child where bone-to-bone fixation of ligament reconstruction
may pose risk of injury to the growth plates. Index finger polli-
cization is also performed around 2 years of age when the ves-
sels and nerves can be more easily dissected, thus making the
operation safer. Although still debated, authors have shown that
functional outcome after pollicization is not significantly di er-
ent if the procedure is deferred until late childhood, and the
outcomes of these procedures improve as children grow.
The surgical options and authors’ preferred methods for
reconstruction are outlined below.
34.4.1 First Webspace Deficiency
Widening of the first webspace is the most e ective procedure
to improve function in patients with congenital hand di erences.
There are many options—local transpositions flaps, local rota-
tional flaps with or without skin grafts, regional vascular island
flaps, free tissue transfer, distant pedicle flaps, and use of skin
expanders. For most congenital cases, local tissue rearrangement
using the four-flap Z-plasty provides the best result (Fig. 34.8).
The contractual limb of the Z-plasty is marked first, followed
by the limbs at opposing ends (transverse limbs), each at 90
degrees to the first limb. On the volar side, the transverse limb
usually follows the distal palmar flexion crease. On the dorsum,
the transverse limb parallels the metacarpal of the first ray. The
flaps are incised and raised in the subcutaneous plane. The fas-
cia overlying the thenar intrinsic muscles should be excised
while protecting the neurovascular bundles. The flaps then
“fall” into place and can be secured using 6–0 chromic sutures.
Complications are rare.
For larger deficits, most surgeons prefer a dorsally based
advancement flap with or without adjacent full-thickness skin
grafts. Regional or free flap fasciocutaneous flaps are also quite
e ective.
34.4.2 Metacarpophalangeal Joint
Instability
In the newborn, it is di cult to ascertain the stability of the MP
joint. However, as the child gets older, it becomes obvious on
inspection. Children with weak MP joint collateral ligaments
cannot grasp large objects. They will use the metacarpal head
instead of the distal ray to hold objects, as everything beyond
the metacarpal head is unstable. The joint should be examined
in flexion and extension. Apparent laxity of the joint in exten-
sion is occasionally corrected in flexion. Often a narrow first
webspace masks instability of the MP joint.
Stabilization of the MP joint can be accomplished by one of
the following methods: tightening of the existing ligaments and
capsule, free tendon graft reconstruction, arthrodesis or chon-
drodesis, or ligament reconstruction using the end of a tendon
used for opponensplasty. The first method, simple imbrication
and tightening, has not been e ective in the long term.
Arthrodesis or chondrodesis should be reserved as a last resort
or in those with severe instability and poor/absent extrinsic
motors. Accordingly, most surgeons choose ligament recon-
struction using tendon graft.
Tendon graft can be used by itself (palmaris longus) or in the
setting of simultaneous opponensplasty (flexor digitorum
superficialis [FDS]). The techniques are similar. More typically,
if MP joint ligament reconstruction is required, the intrinsic
thenar musculature is also hypoplastic, so simultaneous oppo-
nensplasty is also chosen. The FDS tendon to the fourth digit is
usually used ( Fig. 34.9). An A1 pulley incision is made in the
palm and the FDS is divided as distal as possible. There can be
adhesions to the fifth digit FDS or a distal bifurcation that
requires a separate incision in the palm. The FDS is then
retrieved through a separate incision over the distal wrist
crease. It is looped around the flexor carpi ulnaris (FCU) and
directed subcutaneously toward the radial aspect of the thumb
MP joint. A separate slip of FCU is not used for a loop given that
it causes additional adhesions. The FDS slips are separated
along the fibers of the tendon until a point where it would pro-
vide maximal abduction. A transverse bone tunnel is made in
the head of the metacarpal and one slip is passed through and
secured with sutures—note that the growth plate of the meta-
carpal is proximal. A subperiosteal tunnel is made (dorsal to
palmar) distal to the grow th plate along the metaphysis of the
proximal phalanx. The tendon is passed beneath the extensor
shroud and through this subperiosteal tunnel, dorsal to palmar,
and sutured to itself. Stabilization on both sides of the joint is
usually needed. This technique can be modified to just use
a free tendon graft if simultaneous opponensplasty is not
performed.
Fig. 34.8 First webspace release with four-flap Z-
plasty.
Upper Extremity
320

34.5 Lack of Palmar Abduction
and Opposition
Opposition transfer using one of two methods is preferred in
hypoplastic thumbs: FDS tendon transfer from the fourth digit
or abductor digiti minimi (ADM) transfer (with or without
skin). The FDS transfer is preferred in cases where simultaneous
ligament reconstruction is planned, and is usually the more
commonly used method. The technique is outlined in the pre-
vious section.
In patients who need only opponensplasty (such as after
index finger pollicization with poor opposition), the ADM tech-
nique is preferred. The muscle is raised through a high midlat-
eral incision extending from the pisiform to the midaxial line of
the proximal phalanx. If desired, a skin island can be taken with
the muscle, thus providing the advantages of improving soft-
tissue deficit and minimizing tightness of the tunnel
(Fig. 34.10). The ADM muscle is identified and its insertion is
divided with a small subperiosteal extension. The sensory
branch of the ulnar nerve is identified and protected. The
muscle is raised proximally to its origin at the pisiform, with
care to avoid injury to its neurovascular pedicle. A radial inci-
sion over the thumb MP joint exposes the aponeurosis. The
muscle is then passed through a generous subcutaneous pocket
between the skin and palmar fascia and then attached to the
radial aspect of the MP joint or abductor aponeurosis.
34.6 Index Finger Pollicization
Pollicization of the index finger is the ideal reconstruction for
patients with types IIIB, IV, and V hypoplastic thumbs. Patients
with a five-fingered hand undergo a similar procedure, a rota-
tion–recession osteotomy, of the most radial digit.
The authors have outlined the technique for index finger pol-
licization in previous publications. The major goals are creation
of a vascular island, rotation and recession with shortening of
the metacarpal, rebalancing of the muscles and tendons, and
creation of a normal-appearing first webspace. The procedure
shortens the index finger and places it into a pronated,
abducted position (Fig. 34.11).
Fig. 34.9 Metacarpophalangeal joint ligament reconstruction using flexor digitorum superficialis from the ring finger. (a,b) The ligament is routed
around the flexor carpi ulnaris tendon and delivered on the radial side of the metacarpophalangeal joint. (c,d) Immediate and long-term postoperative
outcomes are shown.
Thumb Hypoplasia
321

A racquet-shaped incision is planned around the index finger.
The incision extends onto the palm where the normal thenar
flexion crease would lie. An esmarch bandage exsanguinates
the limb and is used as a tourniquet in the upper arm. The dor-
sal incision is made and two longitudinal veins can be found on
either side of the extensor tendon and dissected proximally.
They are located in a plane between the two layers of fat. The
volar incisions are then made and the radial and ulnar neuro-
vascular bundles are identified and dissected free. The contri-
bution of the common digital vessel to the middle finger is
ligated and divided. The intermetacarpal ligament is divided.
The A1 pulley is divided. The intrinsic muscles to the index fin-
ger are mobilized o the bone with a small distal periosteal
sleeve. The extra periosteum of the metacarpal is discarded to
avoid ectopic bone formation. A volar oblique osteotomy is
made in the metacarpal base; the retained dorsal cortex will be
used to stabilize the metacarpal head, which becomes the new
trapezium. The metacarpal head is then transected at the
physis, and the physis is ablated. The metacarpal head is
secured to the oblique-cut metacarpal base in a hyperextended
position. Hyperextended placement helps to avoid future
hyperextension of the joint in situ as it locks it in maximal ex-
tension in a position of function. Pins are usually not required;
one or two permanent sutures will su ce. At this point, the
extensors are rebalanced. The previous extensor digitorum
communis is transected and sutured to the base of the proximal
phalanx on its ulnar dorsal edge—this tendon will be the new
abductor pollicis longus. The extensor indicis proprius tendon
is shortened by the amount of metacarpal that is excised. This
tendon becomes the new extensor pollicis longus. Side-to-side
suturing is acceptable and works well. The intrinsics muscles
are attached to bone or the extensor mechanism. Once reba-
lancing is complete, the neothumb should be held in neutral
to slight extension, but be easily flexed with gentle pressure
by the surgeon. With the new thumb held in its new posi-
tion, the skin is then draped, contoured, and sutured to pro-
duce a harmonious webspace. The reconstruction is
immobilized using a well-padded long arm cast for 3 to 4
weeks. Night splinting can commence for another month once
the cast is removed. The flexors are not usually shortened,
but in most children the flexor will shorten spontaneously
over a few months.
34.7 Outcomes
Reconstructive procedures for thumb hypoplasia mimic the
appearance and function of a thumb, but do not approach the
range of motion, strength, and appearance of a normal thumb.
Nevertheless, studies have shown that functional outcomes
after reconstruction, including pollicization, are quite satisfac-
tory. After pollicization, total active range of motion averages
about 50% of normal, grip strength is 21% of normal, and use in
normal activities is 84% of normal. The results are not signifi-
cantly altered by age at the time of the operation, as long it is
performed during childhood. Postpollicization data show that
the preoperative condition of the index finger has the greatest
influence on the functional outcome of the thumb. The better
the status of the index finger, the better the ultimate functional
outcome of the new thumb. Rigid, sti transferred index fingers
often seen in syndromic patients serve as stable posts for rudi-
mentary grip and pinch.
34.8 Complications
Index finger pollicization is a technically demanding opera-
tion, especially when performed in small children. The struc-
tures are small, as is the margin of error. Devascularization
due to injury to the arteries or, more commonly, the veins
can occur. Arterial injuries should be recognized and immedi-
ately repaired. Venous problems can arise even without dam-
age to the veins, such as by compression or kinking. If a vein
is injured, it should be repaired. In the case of kinking or
compression, the o ending problem should be recognized
and addressed. Wounds should be opened and all compres-
sion relieved.
Fig. 34.10 Abductor digiti minimi myocutaneous flap transfer for palmar abduction. (a) Preoperative, (b) intraoperative, and (c) postoperative views
are shown.
Upper Extremity
322

Nonunion of the metacarpal head and growth arrest of the
proximal phalanx can be seen. These problems may be due to
overdissection and manipulation of the blood supply. Con-
versely, if the grow th plate of the metacarpal head is not
ablated, overgrowth of the new trapezium can cause the thumb
to be too long.
Skin flap necrosis can be seen with resulting contractures.
These issues can be avoided with meticulous handling of the
soft tissue and careful design of flaps and incisions.
By far the most common long-term problems arise from mal-
positioning the index finger in its new position. Very careful
attention should be paid to the pronation and abduction of the
new thumb to avoid the look of a short index finger in the same
plane as the hand—a poor functional reconstruction.
Complications from reconstructive procedures such as first
web release, collateral ligament reconstruction, and opponens-
plasty are not as common. Most of these stem from poor tech-
nical execution or inadequate postoperative immobilization.
34.9 Conclusion
The thumb is the most important ray of the hand; thus, all
e orts must be made to improve function in a patient with
thumb hypoplasia. The Blauth classification system provides a
good framework for diagnosing and treating these thumbs.
Functional outcomes are satisfactory, but they provide only a
fraction of the function of a normal thumb. Newer outcome
Fig. 34.11 Index finger pollicization. (a,b) show
markings. (c-e) Extrinsic extensors ready to be
rebalanced, intrinsic muscles and metacarpal fully
exposed, and inset of the metacarpal head into
the base. (f,g) Immediate postoperative out-
come.
Thumb Hypoplasia
323

instruments are being developed that can help better quantify
function after these types of reconstructive procedures.
Suggested Readings
Blauth W. The hypoplastic thumb [in German]. Arch Orthop Unfallchir. 1967;
62(3):225–246
Buck-Gramcko D. Pollicization of the index finger. Method and results in
aplasia and hypoplasia of the thumb. J Bone Joint Surg Am. 1971; 53
(8):1605–1617
Flatt A. The Care of Congenital Hand Anomalies. 2nd ed. St Louis, MO: Quality
Medical Publishing; 1994
Littler JW. The neurovascular pedicle method of digital transposition for
reconstruction of the thumb. Plast Reconstr Surg (1946). 1953; 12(5):303–
319
Manske PR, McCarroll HR , Jr. Reconstruction of the congenitally deficient
thumb. Hand Clin. 1992; 8(1):177–196
Manske PR, McCarroll HR , Jr, James M. Type III-A hypoplastic thumb. J Hand
Surg Am. 1995; 20(2):246–253
Taghinia AH, Littler JW, Upton J. Refinements in pollicization: a 30-year expe-
rience. Plast Reconstr Surg. 2012; 130(3):423e–433e
Upton J, Taghinia AH. Congenital hand III: Disorders of formation—thumb
hypoplasia. In: Neligan P, Chang J, eds. Plastic Surgery. 3rd ed. Vol. 6. Atlanta,
GA: Elsevier; 2012: 572–602
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35 Syndactyly
Simon G. Frank and Amir H. Taghinia
Sum m ary
Syndactyly is webbing of the digits of the hands or toes. The
condition can be complete, incomplete, simple, or complex.
Syndactlyl usually is sporadic but may be associated with syn-
dromes. Operative correction is performed in early childhood.
Keywords: syndactyly, pediatric, hand, feet, apert
35.1 Introduction
Syndactyly is one of the two most common congenital di eren-
ces of the upper extremity, the other being polydactyly, occur-
ring in approximately 1 in every 2,000 live births. Syndactyly is
most commonly seen in isolation, though it can also be found in
association with other anomalies such as Poland sequence,
Apert syndrome, and the other acrocephalosyndactyly syn-
dromes. In cases of isolated syndactyly, half of a ected patients
have bilateral involvement. Syndactyly is twice as common in
males and there is a family history in 10 to 40% of cases, most
often in an autosomal-dominant inheritance pattern with varia-
ble expression and incomplete penetrance. The feet are more
frequently involved than the hands, though the majority of
cases in the feet are simple, incomplete fusions of the second
webspace, which often go unnoticed. In the hand, the third
webspace is the most frequently a ected (approximately 50%),
followed by the fourth (30%), second (15%), and first (5%) web-
spaces. While syndactyly of the first webspace is uncommon, it
tends to be associated with syndromes and part of a highly
complex syndactyly of the hand.
Syndactyly is typically classified as either complete, in which
the webbing extends to the tip of the digit and involves the nail
complex, or incomplete, in which the webspace begins distal to
the level of the normal commissure but does not extend to the
tip (Fig.35.1). Distinction is next made on the basis of the tis-
sues forming the interdigital connection; a simple syndactyly
involves only skin and abnormal fibrous tissues, whereas a com-
plex syndactyly includes abnormal osseous or cartilaginous
connections. Finally, a syndactyly is termed complicated when
the connections are more than simple side-to-side fusions. The
Apert hand, central polysyndactyly, and typical cleft hand are
examples featuring complicated syndactyly.
The etiology of syndactyly remains unclear. Simple syndac-
tyly can be explained by the failure of programmed cell death
within the webspace, which forms the basis of the traditional
classification of syndactyly as a failure of di erentiation under
the original Swanson/IFSSH (International Federation of Soci-
eties for Surgery of the Hand) system. However, more complex
forms of syndactyly lack a well-accepted cause and there is no
current consensus on their appropriate classification. Recently,
the IFSSH has proposed adopting the OMT (Oberg–Manske–
Tonkin) classification, which categorizes syndactyly in the
“abnormal axis formation/di erentiation–hand plate” subcate-
gory within the larger category of malformations.
35.2 Diagnosis
The diagnosis of syndactyly is made by physical examination.
The involved digits, the extent of the syndactyly, and the
involvement of the nail bed should be noted. The distinction
between a simple and complex syndactyly can often be made
based on the relative motion of the adjacent digits. Examination
should also be performed of the remainder of the upper
extremity, the contralateral upper extremity, and the feet.
Radiographs of the a ected hand should be obtained in most
cases, but are generally unnecessary in the case of simple syn-
dactyly. Imaging by ultrasound, magnetic resonance imaging
(MRI), or angiography may be helpful in the most complex
cases to determine soft tissue and vascular anatomy, or to
describe the bony configuration when bone overlap precludes
accurate determination by plain radiographs. The authors do
not perform routine angiography, MRI, or ultrasound, however.
Further workup or referral to other specialists may be indicated
in syndromic cases of syndactyly, though these patients are
often already involved in a multidisciplinary care team.
35.2.1 Nonoperative Management
There is a limited role for conservative management in syndac-
tyly. Surgical intervention may not be indicated for minor forms
Fig. 35.1 Classification of syndactyly.
Syndactyly
325

of syndactyly in which there is no functional impairment, or it
may be at the discretion of the parents. Particularly in the feet,
incomplete syndactyly can be relatively inconspicuous, and cor-
rection is therefore often unnecessary. Medical tattooing has
been proposed to simulate a webspace in the toes, and has even
been embraced by some patients in a creative manner.
35.2.2 Operative Treatment
Anatomy
Prior to any surgical correction of syndactyly, it is necessary to
understand the normal anatomy of the webspace (Fig. 35.2).
The normal interdigital webspace has an hourglass shape, and
is inclined 45 degrees from dorsal to palmar. The second and
fourth webspaces are wider than the third webspace, consistent
with the greater abduction possible with the index and small
fingers. The norm al position of the base of the commissure is
the midportion of the proximal phalanx (when the fingers are
maximally splayed apart), which is approximately halfway
between the distal palmar crease and the proximal interphalan-
geal joint crease. These landmarks place the second and third
webspaces at the same level, with the fourth lying slightly prox-
imal. The first webspace “has the configuration of a diamond-
shaped tetrahedron,” with triangles of glabrous skin volarly and
nonglabrous skin dorsally. The edge of the web extends as a
smooth arc from the level of the index metacarpophalangeal
joint to a point just distal to the thumb metacarpophalangeal
joint.
The abnormalities present in syndactyly can be highly varia-
ble. In all cases, there is a deficiency of skin, which can be dem-
onstrated to parents by comparing the measurement of the
circumference of two digits held together versus the sum of the
circumferences of the individual digits. The deficiency is partic-
ularly pronounced in the area of the normal commissure,
explaining the need for skin grafts in this area with most
releases. The fused digits are connected in the midaxial line
along the length of fusion by an abnormal fascia. The digital
nerves and arteries are often abnormal with regard to their
branching patterns, most frequently bifurcating more distally
than normal, especially in more severely a ected cases. This
distal bifurcation may limit the extent of separation of the digits
or may (rarely) necessitate ligation of one of the digital arteries
and intraneural separation of the digital nerves. In complex
syndactylies, the skeletal union is usually at the level of the dis-
tal phalanx, but can be along the entire digit in some cases.
Finally, in complicated syndactylies, the anatomy can be highly
abnormal, including duplications within the web (polysyndac-
tyly), transversely oriented skeletal elements, joint abnormal-
ities, and abnormalities of the phalanges, to the point where
recreation of a normal, useful digit is impossible.
Indications
As already noted, surgical treatment is the mainstay for syndac-
tyly. Exceptions include the aforementioned minor cases of syn-
dactyly with no functional impairment, particularly in the feet,
as well as highly complex syndactylies in which surgery may in
fact worsen function. Severe medical comorbidities can also
present a contraindication to surgery.
Timing of Surgery
Historically, release of syndactyly has been performed anytime
from the neonatal period to well into childhood. Children estab-
lish patterns of prehensile function by 24 months of age, which
many feel serves as an upper limit for completing releases. The
timing of surgery is often influenced by how much surgery is
needed—since most surgeons advocate against releasing neigh-
boring webspaces simultaneously, patients with multiple
Fig. 35.2 Illustration of the 45-degree inclination
and hourglass configuration of the normal web.
Upper Extremity
326

syndactylies require multiple operations to complete the entire
release. Neonatal surgery has been advocated due to the abun-
dance of mobile skin and thus the ability to avoid skin grafts;
however, this is not routinely performed by most surgeons.
There remains no consensus for ideal timing of surgery, though
most surgeons favor performing releases between 9 months
and 2 years of age. In most cases, there is no harm in waiting
until the child is older, though parents are often eager to have
releases performed sooner. Certain cases, however, warrant ear-
lier intervention, specifically release of the first and fourth web-
spaces, as well as complex cases in which multiple surgeries are
planned. In the case of complete syndactylies of the first or
fourth webspace (especially in cases where distal bony coalition
is present), surgery is best performed early to avoid progressive
skeletal deformity and flexion contractures, and to allow for the
development of pinch in the case of the first webspace
(Fig. 35.3). In complex cases, the first of multiple surgeries
may need to commence earlier than normal to allow for com-
pletion of all releases within an appropriate time frame, as well
as to allow for possible intervening procedures by other special-
ists in the case of children with associated anomalies.
Surgical Principles
A variety of techniques have been described in the history of
syndactyly release. Successful techniques will generally adhere
to a number of principles, though there are always exceptions.
Surgery should only be performed on one side of the digit at a
time to avoid vascular compromise to the digit or the skin flaps.
The commissure should be resurfaced with some type of skin
flap. Zigzag incisions should be used volarly to avoid flexion
contractures. When needed, skin grafts should be full thickness.
Finally, care must be taken with postoperative dressings and
immobilization.
Release of Incomplete Syndactyly
In situations in which only mild deepening of the webspace is
required, a variety of local flaps have been described. The
majority of proposed repairs involve some manner of double-
opposing Z-plasties, as in the “jumping-man” flap. As the syn-
dactyly begins to approach the proximal interphalangeal joint,
one should consider a formal syndactyly release.
Release of First Webspace
As previously mentioned, syndactyly of the first webspace is
more common in syndromic cases, such as Apert syndrome.
Reconstruction of this unique webspace can also be considered
in the context of hypoplastic thumb as well as trauma, and
many of the same techniques can be applied to syndactyly.
For minor deficiency of the first webspace, a variety of Z-plas-
ties have been described. A standard single Z-plasty with large
flaps may be su cient, but the four-flap Z-plasty is ideally
suited to this situation, and provides good length and contour
of the webspace ( Fig. 35.4).
With more significant deficiency, tissue must be introduced
into the webspace to provide adequate abduction and grasp.
Many local flaps have been described, both with and without
the use of skin grafts, including transposition flaps from the
Fig. 35.3 Demonstration of angular deformity
due to complete complex syndactyly involving
the fourth webspace. (a) Dorsal view. (b)
Oblique view. (c) Radiographic view.
Fig. 35.4 Four-flap Z-plasty for deepening of the first webspace. (a) Preoperative markings. (b) Intraoperative view after elevation of flaps. (c) Final
view showing inset of flaps.
Syndactyly
327

dorsum of the thumb or index finger, rotation or transposition
flaps from the dorsum of the hand, and V-Yadvancement flaps.
An advancement flap of the dorsal skin into the defect is an
e ective technique. The necessary skin grafts should be placed
along the adjacent borders of the thumb or index finger rather
than across the webspace. This technique takes advantage of
the mobile dorsal skin and allows repeated advancement of the
tissue if required.
Regional flaps, such as the reverse radial forearm flap or
reverse posterior interosseous artery flap, are sometimes needed
in severe cases such as the typical cleft hand, certain symbrachy-
dactylies, and the mitten hand. Though these regional options
provide ample skin, they can be bulky in a young child due to
the thickness of the adipose layer, and they also leave the child
with a potentially unsightly donor site on the forearm. Free flaps
may also be used, and have been described from the lateral arm,
groin, and contralateral forearm.
In addition to adequate soft-tissue coverage, release must
also be performed of fibrous bands between the thenar
muscles, and possibly of the carpometacarpal joint. The vascu-
lar anatomy is frequently abnormal; therefore, care should be
taken during the dissection, and division of the branch of the
common digital artery leading to the index finger must occa-
sionally be performed provided the index finger has adequate
circulation from the ulnar side. Finally, it is occasionally prefera-
ble to perform a ray resection of the index finger as long as
three functional fingers remain.
Release of Complete Simple Syndactyly
A multitude of techniques have been described for the release
of the complete simple syndactyly. Conceptually, the operation
can be thought of as three components: the flap used to line the
commissure, the digital flaps and skin grafts used to line the
fingers, and the reconstruction of the nail folds. Nail fold recon-
struction will be discussed in the following section.
The majority of current techniques use a dorsally based rec-
tangular (or hourglass-shaped) flap to line the commissure,
though a combination of dorsal and volar triangular flaps can
also be used. Rectangular flaps theoretically best approximate
the configuration of the normal commissure, while interdigitat-
ing triangular flaps allow greater flexibility in their inset, which
may be of value in more complex cases where one may not be
able to achieve the full depth of the web due to anatomic abnor-
malities. Lateral tabs can also be added to the rectangular flaps,
which when rotated down into the commissure can help line
the lateral aspect of the digits, reducing or eliminating the need
for skin grafts at the expense of a scar on the dorsum of the
hand and the potential for tighter closure.
Flaps to line the digits are typically made using zigzag inci-
sions dorsally and volarly, though some incorporate a volar rec-
tangular flap proximally to reline the lateral aspect of the digit
adjacent to the commissure, while still other techniques make
use of straight-line incisions dorsally. With standard zigzag inci-
sion, techniques vary in the acuity of the angles for the flaps:
more acute angles will ensure there are no straight-line scars
along the digit that could lead to contracture, while more obli-
que angles will provide better vascularity to the tips of the flaps.
Finally, when skin grafts are required, full-thickness skin is
preferable for its decreased contraction and improved appear-
ance. A number of potential sources for skin have been
described. The hypothenar eminence provides skin from the
same operative field, though it can be thick and nonpliable. Skin
can be obtained from various sites on the arm including the
volar wrist crease, the antecubital fossa, and the medial upper
arm, though all these leave potentially visible scars. The fore-
skin can be used at the time of circumcision, and though this
skin is otherwise discarded, using it as a graft can result in
undesirable pigmentation. Finally, the inguinal crease or lower
abdomen can provide large amounts of skin and leave an incon-
spicuous scar, for which reasons many authors consider it an
ideal donor site provided the future hair-bearing skin is
avoided. Though there is an appeal to avoiding skin grafting,
the use of a skin graft on the lateral aspect of the digit in fact
o ers few downsides and should be used without hesitation if
there is concern regarding an overly tight closure.
The authors’ preferred technique, consisting of a dorsal hour-
glass-shaped flap and dorsal and volar zigzag incisions, will be
described ( Fig. 35.5). Markings are made of the dorsal skin
dimples, denoting the metacarpophalangeal joints. These points
Fig. 35.5 Markings for complete simple syndactyly release. (a) Dorsal view. (b) Volar view.
Upper Extremity
328

form the base of the hourglass-shaped flap. The distal extent of
the flap is marked a few millimeters distal to the planned level
of the commissure to allow for loss in length of the flap as it is
rotated volarly. Laterally, the flap extends to the midline of the
digits. The level of the commissure can be determined by a
number of methods. Comparison is made to the adjacent web-
spaces, recalling that the fourth webspace lies slightly proximal.
The contralateral hand can be examined and measurements
taken. Finally, the commissure should lie at the midportion of
the proximal phalanx when the fingers are maximally splayed
apart. This point is approximately halfway between the distal
palmar crease and the proximal interphalangeal joint crease.
Zigzag incisions are then marked on the dorsum of the digits,
with lines connecting the adjacent proximal interphalangeal
joints and similarly the adjacent distal interphalangeal joints.
Markings are then completed to form the triangular flaps, tak-
ing into consideration which orientation of markings will yield
an appropriately angled set of flaps. The markings extend later-
ally to the midpoint of each digit.
Attention is then turned volarly. A transverse line is marked
volarly approximately a millimeter proximal to the level of the
planned commissure to allow for creep, extending laterally to
the midline of each digit. A small triangular flap is added at the
midpoint of this line, which will serve to break up the linear
scar along the base of the commissure. This triangular flap will
be inset into a small longitudinal incision made into the rectan-
gular flap at the time of closure. A set of zigzag markings that
matches the dorsal markings is then made. Volar and dorsal
markings should be confirmed to ensure the flaps will inset
appropriately once raised.
After exsanguination and inflation of the tourniquet, the rec-
tangular flap is incised and raised in the subcutaneous plane.
The web is released, taking care to avoid damaging the mirror-
ing flaps during incision, particularly distally where the web-
bing may be thin with minimal intervening soft tissue. Flaps are
raised to the midline. The digits are held in abduction, and the
neurovascular bundles are identified as they approach the com-
missure. The interdigital fascia is incised to allow release of the
digits, and preferably excised, particularly if thick and fibrous.
Dissection continues as far proximally as required or as dictated
by the branching of the neurovascular structures. Intraneural
dissection and ligation of an arterial branch may be required, as
long as each digit retains a digital artery on at least one side. If
there is any doubt about the vascular anatomy, adequate circu-
lation should be confirmed by applying a microvascular clamp
to the branch to be divided, deflating the tourniquet and verify-
ing that all digits remain well perfused. Conservative defatting
of the digit may be performed if necessary for closure, taking
care to protect the neurovascular bundles.
If present, synostoses may be divided with a knife or small
osteotome in younger children, while an oscillating saw may be
required for older children. Duplicated skeletal components
may be excised and collateral ligaments re-inserted. Where
necessary, corrective osteotomies are generally deferred to a
second stage when the child is older.
Flaps are inset, taking care to avoid excess tension. A small
releasing incision is made at the midpoint of the dorsal rectan-
gular flap to accept the volar triangular flap. Absorbable sutures
such as 5–0 or 6–0 chromic gut are generally preferable in the
younger patient. After inset is complete, the tourniquet is
deflated and hemostasis obtained with bipolar cautery. Tem-
plates are made of open areas using the foil from a suture pack-
age, and full-thickness grafts are harvested, defatted, and inset
(Fig. 35.6). Block of the digits may be performed at this point
using 0.25% plain bupivacaine.
Application of an appropriate dressing is critical. An antibi-
otic-impregnated nonadherent gauze is applied to the incisions
and grafts, followed by lightly moistened gauze and then an ad-
equate amount of moistened cotton to stent the webspace. A
bulky dry gauze dressing is then secured using Kling wrap. The
extremity is immobilized in a well-padded long-arm cast with
the elbow in flexion. The cast should be left on for 3 weeks.
Once the cast is removed, the parents are encouraged to wash
the extremity in the bathtub and rub the incision areas with a
moist washcloth. A hand therapist will make a splint with a sili-
cone webspace conformer to stent the webspace open and put
pressure on the incisions. This splint/conformer should be worn
at night for 1 month after the cast is removed.
Fig. 35.6 Complete simple syndactyly release following inset of flaps and skin grafts. (a) Dorsal view. (b) View of commissure demonstrating inset of
small volar triangular flap into releasing incision on distal aspect of hourglass-shaped flap.
Syndactyly
329

Reconstruction of Nail Folds
Successful reconstruction of the nail fold remains a challenge,
for which a variety of techniques have been described. Prior to
reconstruction of the folds, it is important to trim the nail
matrices and underlying bone down to an appropriate width.
Following this step, for minor deficiencies the lateral skin can
be undermined and simply advanced. Alternatively, release of
the fingertip can be performed asymmetrically, covering one
side with local skin and the other with a full-thickness skin
graft. Composite grafts of skin and pulp from the toe may also
be used. Finally, the nail fold flaps of Buck–Gramcko are e ec-
tive and are preferred by many surgeons. Ultimately many of
the described techniques result in ischemic flaps of question-
able utility, and if used, flaps should therefore be fairly wide.
Apert Syndrome
The hand deformity seen in Apert syndrome consists of a com-
plex syndactyly of the index, long and ring fingers joined by a
simple syndactyly to the small finger. The thumb is short, is var-
iably joined to the central mass, and may have a radial clinodac-
tyly. There is frequently a synostosis of the base of the ring and
small finger metacarpals. There are also typically deformities of
the shoulder and elbow, though these are rarely treated
surgically. Upton has classified the Apert hand into three cate-
gories (Table 35.1). The unique abnormalities seen in the syn-
drome dictate certain modifications to standard syndactyly
releases. The symphalangism and resultant lack of interphalan-
geal joint motion in the central three digits allows for straight-
line releases along the digits without concern for flexion con-
tracture ( Fig. 35.7). Because of the potential for neurovascular
abnormalities within the webspaces, interdigitating triangular
flaps are generally used for commissure reconstruction to allow
for greater flexibility in setting the depth of the web. When
covering the lateral aspect of the digits, many surgeons prefer
to leave distal areas open and allow them to epithelialize, while
alternatively full-thickness grafts may be applied directly over
exposed bone with generally satisfactory results. Regardless of
preference in this regard, requirements for skin graft are gener-
ally large, making the lower abdominal donor site ideal, partic-
ularly when performing bilateral releases as is often the case in
Apert syndrom e. Finally, the complexity of the Apert hand
necessitates a staged approach, and the surgeon should not hes-
itate to o er revisions as the child grows.
Many treatment algorithms have been proposed, which vary
primarily in how the digital separations are staged, as well as
timing of the operations. Irrespective of which algorithm is fol-
lowed, the timing of surgeries will need to be coordinated with
the craniofacial team.
Table 35.1 Classification of the Apert hand
Type I (“obstetrician’s hand” or “spade
hand”)
Type II (“cup hand” or “mitten hand”)

Type III (“rosebud hand” or “hoof hand”)
Thumb

Free; radial clinodactyly

Joined by simple syndactyly; radial
clinodactyly
Joined by tight complex syndactyly; radial
clinodactyly may be absent
Central mass Flat plane; complex syndactyly

Cupped transverse arch with splaying of
digits at metacarpophalangeal level;
complex syndactyly
Tightly cupped transverse arch with
incorporation of thumb; complex
syndactyly
Fifth digit

Joined by simple syndactyly, typically
incomplete
Joined by simple syndactyly, typically
complete
Joined by complex syndactyly
Fig. 35.7 Markings for release of syndactyly in an
Apert hand. Note use of straight-line incisions
and triangular flaps. (a) Volar view. (b) Dorsal
view.
Upper Extremity
330

Release of the thumb webspace is critical and should be done
early. This can be accomplished with the standard techniques
already described, bearing in mind that re-advancement will
likely be required at a future stage. In severe type III hands,
there may be limited tissue available to advance into the web-
space, in which case free tissue transfer can be considered.
Alternatively, skin grafts can initially be used on the sides of the
web followed by successive re-advancement of the dorsal flap.
Finally, the type III Apert hand represents one of the situations
in which sacrifice of the index ray may be preferable in order to
reconstruct an adequate web. Whichever technique is used, the
eventual lengthening of the thumb phalanx at the time of clino-
dactyly correction will improve the webspace.
At the time of thumb webspace release in type III hands, the
tightly bunched digital mass can be converted to the flat config-
uration of a type I hand by performing distal osteotomies of the
digital synostoses through a hyponychial incision. The digits are
then held in a more collinear arrangement with a single trans-
verse K-wire. This procedure makes subsequent releases much
more straightforward, and also improves the maceration of the
nail beds. In type I or II hands where this procedure is not
required, the fourth webspace syndactyly is generally released
at this time to preserve mobility and prevent further deformity
to the fifth digit.
Staged release of the remaining digital syndactylies is then
performed, with the goal of completing the releases well before
school age. As with the first stage procedures, these surgeries
should be performed bilaterally. A two-team approach can be
helpful to minimize anesthetic time.
Despite best e orts in correcting these hands, they will never
look nor function normally. Additionally, they will inevitably
require revisions, with rates approaching 100%. Web creep can
be particularly pronounced in the second web due to the addi-
tional epiphysis at the metacarpal base. Some surgeons there-
fore prefer a dorsal rectangular flap in this webspace given it
can be re-advanced as needed. Other potential revisions include
repeat ostectomy of the synostosis between the fourth and fifth
metacarpals, as it often reforms. Various techniques have been
proposed to limit this recurrence including the use of interposi-
tion fascia, fat, or cadaveric dermis grafts.
Poland Sequence
In addition to the chest wall deformities discussed elsewhere in
this book, the hand in Poland sequence can be hypoplastic with
variable symbrachydactyly. The central digits are more fre-
quently a ected. Treatment is customized to the deformity and
should follow standard principles for syndactyly release, though
many surgeons prefer to exaggerate the depth of the webspace
in patients with short digits, possibly including a release of the
intermetacarpal ligament. Hand surgeries should be coordi-
nated with the rest of the patient’s treatment plan.
35.3 Complication
Early complications from syndactyly release include infection,
graft loss, and flap necrosis, all of which can generally be man-
aged without further surgery. Many of these complications can
be avoided with adequate postoperative immobilization, which
is particularly crucial to avoiding graft loss. Large areas of graft
loss necessitating regrafting are rare, though regrafting should
be considered especially on the volar surface or close to the
depth of the web. Rarely, adhesion of the fingers can occur,
requiring a repeat release.
Late complications include web creep, scarring, deviation of
the digits, joint instability, and complications related to skin
grafts such as pigmentation or hair growth. Re-deepening of
webspaces, particularly in the case of the first webspace, may
be required. This complication may be partially avoided by
thorough release of the fascial bands within the first webspace
at the time of initial surgery. Appropriate flap selection in cases
where recurrence is expected, as in Apert syndrome, allows for
re-advancement of the flaps. In all cases, formation of scar con-
tracture or hypertrophic scars may necessitate excision and clo-
sure by skin grafting and re-advancement of flaps where
possible. Rotational and angular deformities are more common
after complex syndactylies, and may require osteotomies.
35.4 Conclusion
The surgeon should master a few e ective techniques for treat-
ing syndactyly and use them consistently. Once mastered, those
techniques can then be modified based on experience. Regard-
less of which techniques are used, immobilization is critical to
avoiding complications. Following surgery, patients should be
followed closely as they grow so that any problems with web
creep can be addressed early. Additionally, cases should be
carefully documented with photographs. The combination of
thorough documentation and ongoing observation of the pa-
tient allows for the “if/then” feedback necessary for the surgeon
to learn and improve.
35.5 Key Points
● Border digits should be released early to avoid progressive
deformity and ensure optimal hand function.
● During separation of syndactyly, care must be taken to avoid
damage to the neurovascular structures, which become
increasingly anomalous as the complexity of the syndactyly
increases.
● Adequate postoperative immobilization is critical to obtaining
satisfactory outcomes.
● Management of syndactyly in Apert syndrome requires a spe-
cialized approach, with di erences in timing, goals, and surgi-
cal technique.
Suggested Readings
Fearon JA. Treatment of the hands and feet in Apert syndrome: an evolution
in management. Plast Reconstr Surg. 2003; 112(1):1–12, discussion 13–19
Malik S. Syndactyly: phenotypes, genetics and current classification. Eur J
Hum Genet. 2012; 20(8):817–824
Temtamy SA, McKusick VA. The genetics of hand malformations. Birth Defects
Orig Artic Ser. 1978; 14(3):i–xviii, 1–619
Tonkin MA. Failure of di erentiation part I: syndactyly. Hand Clin. 2009; 25
(2):171–193
Upton J. Management of disorders of separation: syndactyly. In: Mathes SJ,
Hentz VR, eds. Plastic Surgery. Vol. 8. Philadelphia, PA: Saunders Elsevier;
2006:139–185
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36 Polydactyly
Paige M. Fox, Heather L. Baltzer, and Steven L. Moran
Sum m ary
Radial, central, and ulnar polydactyly represents the spectrum
of digital duplications seen in pediatric patients. From soft-tis-
sue-only ulnar polydactyly to complex central polydactyly, the
diagnosis, management, outcomes, and complications of each
duplication type are discussed. Classification systems along
with their inherent strengths and weaknesses are included.
Multiple clinical and radiographic examples are provided. After
reading this chapter, the clinician will feel more comfortable
recognizing, diagnosing, and treating the wide spectrum of dig-
ital duplications.
Keywords: radial polydactyly, ulnar polydactyly, preaxial poly-
dactyly, postaxial polydactyly, duplication, triphalangeal
36.1 Introduction
Polydactyly, classified as a duplication of parts, is the most com-
mon congenital hand anomaly. Polydactyly involving the thumb
is referred to as radial or preaxial polydactyly and duplication
that involves the small finger is referred to as ulnar or postaxial
polydactyly. Ulnar polydactyly is more common in African races,
while radial duplication is more common in the Caucasian and
Asian races. Central polydactyly, duplication of the nonborder
digits, is less common than preaxial or postaxial polydactyly.
Central duplication is often associated with syndactyly and cleft
hand. Its treatment is, therefore, more complex, requiring treat-
ment of the polydactyly, the syndactyly, the central cleft, and
any accompanying webspace tightness.
36.1.1 Radial Polydactyly
Radial polydactyly has an incidence of 1 in every 3,000 births.
Variable degrees of duplication exist and range from widening
of the thumb tip to complete duplication. The most common
classification of thumb duplication has been described by Was-
sel, with type IV representing the most frequent pattern. Types
I, III, and IV refer to bifid phalanges, while types II, IV, and VI
refer to complete phalangeal duplication. Wassel type VII
describes a thumb with an extra, or third, phalanx, also known
as a triphalangeal thumb ( Fig. 36.1). Radial polydactyly with
triphalangism is associated with an autosomal-dominant inher-
itance pattern and genetic mutations within the hedgehog
pathway. The remaining types of preaxial polydactyly are
thought to be the result of spontaneous mutations. Radial poly-
dactyly often occurs in isolation but may be associated with
Fanconi anemia or Holt–Oram syndrome.
36.1.2 Central Polydactyly
Central polydactyly (duplication of the index, middle, or ring
fingers) is often seen in combination with other anomalies,
most commonly syndactyly, known as synpolydactyly. This is
felt to be a heritable condition with a broad spectrum of
phenotypic variability. Stelling and Turek have classified cen-
tral polydactyly into three main types: (1) extra soft-tissue
m ass only, (2) duplication of a digit or partial digit that
articulates with an enlarged or bifid phalanx or m etacarpal,
and (3) duplication of a digit including the m etacarpal and
all soft tissues involved ( Fig. 36.2). In 2015, Wall et al
reviewed 56 hands in 40 patients to establish a radiographic
classification for synpolydactyly. The system is based on
level of duplication with type I representing m etacarpal
duplication and type III representing middle or distal pha-
lanx duplication ( Fig. 36.3).
36.1.3 Ulnar Polydactyly
The original ulnar polydactyly classification by Stelling and
Turek was a three-part classification system similar to that
described earlier for central polydactyly. More commonly, ulnar
polydactyly is classified into types A and B as described by
Temtamy and McKusick. Type A represents a well-formed extra
digit that articulates with the small finger metacarpal or a
duplicate small finger metacarpal ( Fig. 36.4). Type B ulnar
polydactyly describes a rudimentary digit with only soft-tissue
attachments to the small finger ( Fig. 36.5). Type B can present
as a spectrum ranging from a small nubbin on the ulnar border
of the digit to a relatively well-formed digit with only soft-tis-
sue attachment and no articulation. The presence of a nubbin is
thought to represent a remnant or neuroma of a pedunculated
supernumerary digit that autoamputated in utero. Pritsch et al
have proposed a subclassification of type A ulnar polydactyly:
type 1, fully developed sixth metacarpal; type 2, intercalated
supernumerary digit between ring and small finger with
rudimentary metacarpal; type 3, supernumerary digit ulnar to
small finger with rudimentary metacarpal; type 4, digit articu-
lates with fifth metacarpophalangeal joint; and type 5, super-
numerary digit arises from a bifid proximal phalanx. Patients
with type A ulnar polydactyly present with bilateral hand
involvement quite commonly (69%) and also frequently have
foot involvement. The majority of type B ulnar polydactyly is
bilateral.
Type B postaxial polydactyly is uncommon in Caucasian
infants, but relatively common in African American infants,
with respective prevalence of approximately 1 in 1,300 and 1 in
150 live births. Type A is relatively rare and has been reported
as equal between African American and Caucasian patients, but
a recent review demonstrated increased relative frequency
among Caucasians and Hispanic patients compared with Afri-
can American patients. Isolated, nonsyndromic ulnar polydac-
tyly, inheritance is more commonly an autosomal-dominant
pattern, but recessive patterns of inheritance have also been
described. Associated congenital anomalies and syndromes can
also be present with ulnar polydactyly including Ellis–van Cre-
veld, Smith–Lemhi–Optic, McKusick–Kaufmann syndromes,
short-rib polydactyly syndrome I, orofaciodigital syndrome III,
Bardet–Biedl syndrome, Meckel–Gruber syndrome, Greig ceph-
alopolysyndactyly, and Pallister–Hall syndrome.
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