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Surgical Treatment of Congenital Syndactyly of the Hand
Khiem D. Dao, MD, Alexander Y. Shin, MD, Annette Billings,
MD,Kerby C. Oberg, MD, and Virchel E. Wood, MD
Abstract
Syndactyly is a congenital anomalythat may be the most common1,2
orsecond most common3 hand malfor-mation. It may hinder hand
functionif not corrected appropriately duringinfancy. Although the
basic principlesof surgical release of simple syndac-tyly have been
well established, eachpatient requires a thorough assess-ment of
the soft-tissue and bony com-ponents in the syndactylized
region.Reconstruction must be planned care-fully when more than two
digits areinvolved or when the syndactyly isa component of a
systemic congen-ital syndrome.
Embryology
Isolated syndactyly of the hand is es-timated to occur in 1 per
2,000 to 2,500live births.4 It is more common inmales than females
(56% to 84%)4-7
and occurs with equal frequency uni-
laterally or bilaterally. This autoso-mal dominant trait has
variable ex-pression or reduced penetrance.8
Advances in molecular biology haveprovided insight into the
embryolog-ic etiology of syndactyly. During thefourth week of
gestation, the handplate emerges, partially rimmed by adigital
plate. During the fifth week,radial condensations of mesodermwithin
the digital plate form the fin-gers, or digital rays. The digital
raysare separated by webs of interdigitaltissue. Within the
interdigital space,radial apoptotic zones form, and pro-grammed
cell death first indents thedorsal surface. The distal tips
thenseparate, and programmed cell deathcarves out the interdigital
space prox-imally toward the central carpal re-gion. The
interdigital space hasformed by the end of the sixth week,but the
digits continue to elongateand develop ventral tactile pads
andundergo phalangeal differentiation.
On a molecular level, the forma-tion of separate and independent
dig-its occurs via a complicated inter-action between fibroblast
growthfactors (FGFs), sonic hedgehog pro-tein, bone morphogenic
proteins(BMPs), and homeobox transcriptionfactors, with MSX2 the
most im-portant.9-12 These factors, in turn, areregulated by the
apical ectodermalridge (AER), which is known to havea critical role
in determining digitidentity and formation of the inter-digital
space.
Early in limb development, FGF-10 expression within the lateral
platemesoderm induces FGF-8 and FGF-4expression in the distal
ectoderm des-
Dr. Dao is an Orthopaedic Hand Surgeon, West-minster, CA. Dr.
Shin is Assistant Professor, De-partment of Orthopedic Surgery,
Mayo Clinic,Rochester, MN. Dr. Billings is Orthopaedic Res-ident,
Department of Orthopaedic Surgery, LomaLinda University School of
Medicine, Loma Lin-da, CA. Dr. Oberg is Professor of Anatomy,
De-partment of Anatomy, Loma Linda UniversitySchool of Medicine.
Dr. Wood is Chief, Hand Sur-gery Service, Department of Orthopaedic
Surgery,Loma Linda University School of Medicine.
None of the following authors or the departmentswith which they
are affiliated has received anythingof value from or owns stock in
a commercial com-pany or institution related directly or
indirectlyto the subject of this article: Dr. Dao, Dr. Shin,Dr.
Billings, Dr. Oberg, and Dr. Wood.
Reprint requests: Dr. Dao, West Valley Ortho-paedics and Sports
Medicine, Suite 150, 23101Sherman Place, West Hills, CA 91304.
Copyright 2004 by the American Academy ofOrthopaedic
Surgeons.
Syndactyly is a congenital anomaly of the hand that is more
common in males, ispresent bilaterally in 50% of affected patients,
and often is associated with othermusculoskeletal malformations or
systemic syndromes. The goal of syndactyly re-lease is to create a
functional hand with the fewest surgical procedures while
min-imizing complications. For simple syndactyly, surgical
reconstruction can begin atapproximately 6 months, although many
surgeons prefer to wait until the infant is18 months old. Special
situations, such as complex syndactyly and involvement ofborder
digits, may warrant surgical intervention earlier than 6 months.
Reconstruc-tion of the web commissure is the most technically
challenging part of the opera-tion, followed by separation of the
remaining digits. Full-thickness skin grafting isalmost always
required for soft-tissue coverage. Complex syndactyly and
syndac-tyly associated with other hand anomalies warrant special
consideration. After re-construction, patients should be examined
periodically until they have achieved skel-etal maturity because
late complications such as web creep can occur.
J Am Acad Orthop Surg 2004;12:39-48
Vol 12, No 1, January/February 2004 39
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tined to become the AER.13,14 Subse-quently, cooperative
interaction be-tweenAER-generated FGFs and sonichedgehog protein
secreted from thezone of polarizing activity regulatesBMP
expression within the meso-derm, forming a gradient across
thecranial-caudal axis (anterior-posterioraxis) that provides
positional cues fordigit identity.15,16
By mechanisms that are as yet un-clear, AER-generated FGFs then
or-chestrate the production of BMP-regulating molecules that
inducechondrogenesis at digital locations(ie, BMP antagonists
Gremlin17 andactivins18). These FGFs also orches-trate the
expression of factors asso-ciated with the apoptotic cascade
atinterdigital spaces (ie, MSX2,12
Snail11). Thus, within the digital plate,the AER helps establish
digital andinterdigital identity.
As programmed cell death ensueswithin the interdigital zone, the
over-lying AER also begins to regress.However, the AER persists
over thechondrogenic zones, and continuedFGF expression is
associated withdigital growth and extension beyondthe hand plate.19
Because of the com-plex molecular interactions, disrup-tion of
several factors that relate toAER regression, interdigital
identity,or programmed cell death can leadto syndactyly. Ectopic
expression ofthe BMP-modifying factor Grem-lin,17 BMP
overexpression,20 or a re-duction in AER-related FGF
expres-sion11,20 all have been linked to theformation of simple
syndactyly. Con-versely, overproduction of AER-related FGF also has
been associatedwith syndactyly.21 Presumably, bothalterations in
FGF production disruptthe apoptotic cascade.
Three mechanisms are likely to in-fluence syndactyly formation:
correctdigital patterning and the subsequentestablishment of
interdigital identity;induction of the apoptotic cascade;
andregression of the proliferative activ-ity of the AER. For
example, if dig-ital patterning is appropriate and the
AER regresses but a defect in apo-ptosis occurs, interdigital
tissue willpersist but not extend with the digitsas they continue
to elongate. Simplesyndactyly will occur, forming prox-imal
webbing. Alternatively, if digi-tal patterning is appropriate but
theAER persists over the interdigital re-gion and fails to induce
the intact apo-ptotic cascade, the interdigital tissuewill grow
with the digits as they ex-tend beyond the hand plate. Finally,if
there is a disruption in the digitalpatterning, the AER will
persist in in-appropriate locations, and the intactapoptotic
cascade will not be appro-priately activated. Such disruption
canlead to abnormal induction of digi-tal rays, simple or complex
syndac-tyly, and clefting.22 Syndactyly alsomay be secondary to
intrauterine in-sults, such as early amnion rupture,in which the
digits initially developindependently but later fuse in
utero.23
Classification
Syndactyly is classified as simplewhen only soft-tissue
structures areinvolved in the webbing and as com-plex when bone or
fingernails of ad-jacent fingers are involved. With com-plete
syndactyly, the entire length ofadjacent digits is involved in the
web-bing; with incomplete syndactyly, thewebs do not extend the
entire lengthof the digit. Complicated syndactylyis the term used
to label complex cas-es that involve a mixture or collectionof
synostoses.24 Syndactyly of thehand occurs most commonly be-tween
the ring and long fingers (40%to 50%), with the next most
commonsite being between the ring and smallfingers (25% to 28%).6,7
The least com-mon location is between the thumband index finger (7%
to 9%).6,7,23
Associated Conditions
Although syndactyly of the hand typ-ically is an isolated
condition, it may
be associated with other conditions(eg, syndactyly of the toes,
polydac-tyly of the toes, cleft feet) or be a com-ponent of a
syndrome.6 The threemost common syndromes associatedwith syndactyly
are Polands syn-drome, in which the syndactyly is as-sociated with
unilateral hypoplasia ofthe sternal head of the pectoralis ma-jor
muscle and the entire upper ex-tremity23,25; Aperts syndrome,
con-sisting of complex syndactyly of thehand along with
craniosynostosis, hy-pertelorism, exophthalmos, and mildmental
retardation; and acrosyn-dactyly (ie, amniotic disruption
se-quence), in which interdigital cleftsor sinuses are present
proximal to thelevel of the syndactyly. Many of thesesyndromes that
include syndactylyalso have visceral and thoracic abnor-malities
that are close chronological-ly to the embryologic development
ofthe hand. These abnormalities shouldbe addressed before the hand
is sur-gically reconstructed.
Surgical Treatment
The overall goal of syndactyly releaseis to produce a hand with
as manyindependent and functional digits aspossible with the fewest
number ofsurgical corrections and complica-tions. Many techniques
have been de-scribed to accomplish this goal; Up-ton26 reported 46
different methodsused over the past two centuries. Theintent with
each is to produce a webspace commissure that is both deepand
wide27,28 to cover the remainingsides of the digits with as much
lo-cal soft tissue as possible and to cov-er any remaining skin
deficits withskin grafts.
Indications for SurgeryThe major indication for surgical
syndactyly release is a bridge of softtissue, with or without
bony synos-toses, that joins two or more digitsand hinders
functional use of thehand. One contraindication to surgi-
Surgical Treatment of Congenital Syndactyly of the Hand
40 Journal of the American Academy of Orthopaedic Surgeons
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cal release is webs associated with so-called super digits.29
Two types of su-per digits have been described: typeI involves two
metacarpals support-ing a single oversized digit (Fig. 1);type II
involves a single metacarpalsupporting two or more digits
distal-ly. With growth, both types pose sev-eral potential
complications, such asenlargement, deviation, angulation,loss of
motion, and undergrowth.Very rarely can super digits be
recon-structed into normally functioningdigits. In such cases,
surgery to cre-ate two digits often fails because fre-quently one
of the two digits becomesstiff, atrophic, and cosmetically
unac-ceptable.
Another contraindication to sur-gery is complex synpolydactyly,
con-sisting of conjoined fingers that func-tionally move in unison
(Fig. 2).Separating such jumbled masses maysignificantly jeopardize
postoperativefunction.8,30 Surgery also is contrain-dicated in
hands with no active mus-
cular control or in adults whose syn-dactylized digits and hands
are veryfunctional.
Timing of SurgeryAlthough surgical correction may
be started at age 6 months, some sur-geons wait until 18 months.
The typeof syndactyly required also may in-fluence the timing of
surgery. Oper-ating when the infant is at least 6months old allows
the bone and softtissue to grow and minimizes the an-esthetic risks
inherent when operat-ing on an infant younger than 6months.
Furthermore, starting at thisage allows time for staged
reconstruc-tion while the child is growing. How-ever, if border
digits are involved, re-construction may be started as earlyas 3 to
4 months. The differentials inlongitudinal growth rates betweenthe
thumb and index finger and be-tween the ring and little fingers
areso great that, inevitably, bone andjoint deformity develop if
the fingersare not released early (Fig. 3).
However, the optimal age to per-form syndactyly release in a
child, es-pecially for single-web syndactyly ofnearly equal-length
fingers (ie, mid-
dle and ring), is a point of controver-sy. Kettelkamp and Flatt6
recommendwaiting until age 18 months because75% of their cases that
met this agecriterion had satisfactory results. Op-erating at this
age may be acceptablefor simple syndactyly involving onlydigits of
nearly equal length. Theprognosis may be poorer when sur-gery is
delayed beyond age 2 yearsbecause the cerebral cortex patternsof
hand use must be retrained.31 Re-gardless, correction should be
donebefore the child reaches school age.
Multiple-digit syndactyly requiresstaged surgery because
releasing bothsides of a digit at the same time risksnecrosis to
the digit if it is suppliedby only a single artery. For syndac-tyly
that involves all of the digits, thering and long fingers and the
thumband index fingers typically are re-leased first, followed by
the index andlong fingers and the ring and smallfingers in a second
procedure 4 to 6months later. This approach minimiz-es the number
of surgeries and the an-
Figure 1 Anteroposterior radiograph of thehand of a child with a
typical type I superdigit. Attempting to make two digits of thisone
good finger is inadvisable. (Reprintedwith permission from Dao KD,
Wood VE,Billings A: Treatment of syndactyly. Tech HandUpper Ext
Surg 1998;2:166-177.)
Figure 2 Anteroposterior radiograph of acomplex synpolydactyly
showing a jumble ofbones and joints that may function more poor-ly
if separated. (Reprinted with permissionfrom Dao KD, Wood VE,
BillingsA: Treatmentof syndactyly. Tech Hand Upper Ext Surg
1998;2:166-177.)
Figure 3 Complete syndactyly between thesmall and ring fingers
and partial webbingbetween the ring and middle fingers. (Re-printed
with permission from Dao KD, WoodVE, Billings A: Treatment of
syndactyly. TechHand Upper Ext Surg 1998;2:166-177.)
Khiem D. Dao, MD, et al
Vol 12, No 1, January/February 2004 41
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esthetic risk.23 In patients with syn-dactyly of all fingers,
the firstoperation may be done before age 6months.32
Technical ConsiderationsSurgical techniques to manage
syndactyly have not changed radical-ly over the past century.
Dividingwebbed digits by separating themwith a pair of scissors in
the nursery,as was done in the very early 1800s,is not recommended
because of theinevitable risk of flexion contracturescaused by
longitudinal scarring. Afull-thickness skin graft (FTSG) usu-ally
is recommended to cover areasof the fingers not covered by
localflaps. FTSGs are preferred over split-thickness skin grafts
because FTSGshave a lesser tendency to scar andcontract. Pedicle
flaps usually are notrequired for congenital syndactylycoverage.
The surgical plan for syn-dactyly release includes the follow-ing:
establishment of a wide and deepcommissure; separation of the
digitswith zigzag skin incisions both dor-sally and palmarly;
separation of thenail, if necessary; division of any
bonyinterconnections; and application ofFTSGs to deficient
areas.
Surgical TechniqueSurgery should be done under
general anesthesia with a tourniqueton the involved extremity;
the oppo-site groin is prepared for FTSG har-vesting.32 The
commissure is de-signed dorsally to have its medial andlateral base
borders at the midsagit-tal line of the contiguous digits,
start-ing at the metacarpophalangeal joints(Fig. 4). Distally, the
bases of the flapare tapered slightly toward each oth-er to
accommodate the width of theproximal phalanges on either side
af-ter the flap is inset. Making the flaplength approximately two
thirds thelength of the proximal phalanx pro-vides a palmar
commissure edge ap-proximately one third the length ofthe proximal
phalanx, once the flapis inset.23 The distal border of the flap
is shaped like a dart to minimize scar-ring at the commissure
border be-tween the dorsal and palmar skin. Areciprocal V-shaped
incision is thenmarked on the palmar surface of theproposed new
webspace to accom-modate this flap. It is important thatthe created
commissure slope in theproximal-dorsal to distal-palmar
di-rection.
Starting at the distal tip of the dart,the dorsal incision is
extended in azigzag fashion from the midsagittalline of one digit
to that of the adja-cent digit. If two separate nails arepresent,
the dorsal incision is extend-ed distally, bisecting the two
finger-tips. When a complex nail is present,as in a complex
syndactyly, the nailmatrix and nail bed should be divid-ed in line
with the division of the dis-tal phalanges. The nail bed,
matrix,and nail may be narrowed in prep-aration for coverage with a
doubleflap.33 Accordingly, a narrow flap israised parallel to the
distal nail edge,based in the center of the commonpulp to cover one
side (Fig. 5). Theadjacent side of the nail bed is thencovered by a
broader, longer flapbased more proximally on the palmarsurface of
the other digit. The defectremaining after elevating the narrow
flap may be closed primarily, but theone left by the broader
flap may re-quire an FTSG.
The palmar incision for the syn-dactyly release is drawn by
visuallyprojecting the apices of the dorsal zig-zag flaps to the
palmar midsagittalline of each digit. These marks be-come the
geometric center of thebases of the corresponding flaps to
bedesigned on the palmar side. The pal-mar zigzag incision is then
drawn.Proximally, this line meets the centerof the previously drawn
V-shapedpalmar anchor line, which is locatedapproximately at the
junction be-tween the proximal and middle thirdof the proximal
phalanges (Fig. 4, B).
Once all of the skin incisions aremade, the dissection is begun
dorsal-ly by raising the dorsal flaps. The thinnatatory ligaments
near the metacar-pal heads are divided to fully sepa-rate the
digits; the transverse inter-metacarpal ligaments are not
divided.The incision is first taken distally be-tween the nails,
then palmarly. Theinterdigital soft tissue is carefully di-vided to
protect the neurovascularstructures.
If the common digital nerves andarteries bifurcate proximal to
the newcommissure, as is commonly the case,
Figure 4 Dorsal (A) and palmar (B) views. The dorsal flap (a),
the V-shaped palmar flap (b),and the zigzag flaps for the
syndactylized digits. (Adapted with permission from Dao KD,Wood VE,
Billings A: Treatment of syndactyly. Tech Hand Upper Ext Surg
1998;2:166-177.)
Surgical Treatment of Congenital Syndactyly of the Hand
42 Journal of the American Academy of Orthopaedic Surgeons
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they will not require separation andwill not impede insetting
the dorsalcommissure flap. Should they bifur-cate distal to this
site, the digitalnerves must be carefully separatedfrom distal to
proximal. Should thedigital arteries bifurcate distally, thesmaller
of the two arteries can be li-gated if there is only a simple
web-space syndactyly, because both dig-its still will have an
arterial supplybased on the opposite side of the fin-ger. When a
central digit has syndac-tyly on each side (eg, index-middle-ring
finger syndactyly), the digitalartery supplying the side digits
bor-dering the middle finger may be li-gated because they also will
have oneremaining digital arterial supply ul-narly or radially.
Syndactyly of the central digit isless an issue when both sides
of thedigit are not operated on simulta-neously. Alternatively, one
mayclamp a vessel, deflate the tourniquet,and evaluate the
resultant blood flowbefore ligating the artery in question.Vascular
complications are rare whenonly one side of a digit is operatedon
at a time, and neither preopera-tive arteriograms nor exploration
ofthe opposite side of a digit is neces-sary.
Before securing the flaps, excesssubcutaneous fat should be
trimmeduntil only approximately 1 mm ofthickness remains. This
decreasespostoperative edema and the risk ofa tight closure. The
tourniquet is de-flated before skin closure to control
potential bleeding. The dorsal com-missure flap is sewn to its
recipro-cating V-shaped palmar anchor with5-0 absorbable sutures.
The dorsalflaps along the digits are swung pal-marly, and palmar
flaps are swungdorsally and sutured. Tight closureshould be avoided
to minimize flapnecrosis.
Usually one finger may be closedcompletely with skin flaps,
whereasthe other requires an FTSG. Nearly allcases other than a
very simple incom-plete syndactyly require grafting.Harvesting the
FTSG lateral to thefemoral artery prevents future pubichair growth
on the flaps. Other do-nor sites include the antecubital fos-sa and
the medial aspect (ie, instep)of the foot. Care must be taken to
ob-tain an accurate template of the totalarea of skin defect to be
covered. Thistemplate is transferred to the pro-posed donor site
before harvestingthe FTSG. The skin graft also requiresdefatting
before being applied to thedigits to prevent fat necrosis and
graftloss.
Gauze dressings are placed deepbetween the separated digits
becauseany exposed open area can heal andresyndactylize the digits.
As a finalcheck, the vascularity of the digitsmust be evaluated
before casting toensure that the gauze placed betweenthem will not
constrict arterial flow.A long-arm club cast with the elbowflexed
past 110 should be used toprotect the fingers from excessive
mo-tion while the skin graft is consolidat-ing. To allow the wound
to be exam-ined, the cast can be changed at 10days and then
reapplied for 1 weekor more. Examination of the woundscan be
delayed for 3 weeks if no signsof infection are present. Other
thancareful attention to the postoperativedressing and
immobilization, mostchildren do not require extensivetherapy after
the 2 to 4 weeks of im-mobilization required for woundhealing. This
is also true for aftercareof complex syndactyly
reconstruc-tion.
Figure 5 A and B, Creating a nail fold using skin from adjacent
fingertips. a = dorsal flap,b = palmar flap. C, Intraoperative
photograph of double flap being raised. D, The flap is
swungproximally before it is secured with sutures. (Panels A and B
adapted with permission fromDao KD, Wood VE, Billings A: Treatment
of syndactyly. Tech Hand Upper Ext Surg 1998;2:166-177. Panels C
and D courtesy of Professor Dieter Buck-Gramcko, Hamburg,
Germany.)
Khiem D. Dao, MD, et al
Vol 12, No 1, January/February 2004 43
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Special Considerations
Although the techniques describedare adequate for most patients,
otherconditions, such as a short, incom-plete proximal web, complex
syndac-tyly, cleft hand, central polydactyly,and acrosyndactyly,
require alterna-tive techniques.
Incomplete Proximal WebIn hands with short, incomplete
simple syndactyly involving less thanone-third the length of the
proximalphalanx, a three-flap webplasty, asdescribed by Ostrowski
et al,34 is ef-fective in creating a commissure fromexcess web skin
without the need fora skin graft. The flaps are composedof a dorsal
rectangular flap and twoequal-length palmar triangular flaps(Fig.
6). The border between the dor-sal and palmar flaps should be at
themost distal extent of the web. The op-timal ratio of the length
to be recessedand the width of the web space is 1:1,although ratios
of 1.5:1 have beenused without complication.35
For incomplete thumbindex fin-ger syndactyly or other mildly
nar-rowed webs, a four-flap Z-plasty36 ora central V-Y with lateral
Z-plasty37
can be used to both widen and deep-en the web space. These
techniquesavoid the need for a skin graft on thelateral walls,
which are the workingsurfaces of the thumb web.24 For anarrow first
web space, a dorsal trans-positional flap can create a function-al
working surface38 (Fig. 7).
Complex SyndactylySyndactyly involving bony inter-
connections between adjacent digitsrequires a plan that
prioritizes the ear-ly establishment of normal or near-normal
osseous architecture, afterwhich the definitive web release maybe
staged. A synostosis may be sep-arated simultaneously with the
syn-dactyly release by using a knife or anosteotome. Phalangeal
angulation iscorrected with closing wedge osteot-omies and held
with a longitudinal
Kirschner wire passed centrallythrough the pulp and advanced
inretrograde fashion. The wires are cutwith 1 cm protruding outside
the skinfor ease of removal (without anesthe-sia) 4 weeks
postoperatively. If thedistal or proximal interphalangealjoints are
not stable, the collateral lig-aments also must be advanced
ortightened.23
In an extremely complex syndac-tyly, sacrificing a nonfunctional
rayand establishing a three-fingered
hand provides the best functional re-sult. Although resection is
difficult forparents to accept, it is a necessary partof the
preoperative discussion in cer-tain instances.
Cleft HandCleft hand deformities usually in-
volve a central ray deficiency withwebbing between the two
remainingdigits of each border component (ie,ring-small finger
syndactyly, thumbindex finger syndactyly). The stan-
Figure 6 Dorsal (A and B) and palmar (C and D) views of the
three-flap webplasty, whichis excellent for incomplete simple
syndactyly or web creep in recurrent syndactyly. Usually,no skin
graft is required. A, Dorsal flap is raised. B and D, Rotation and
inset of dorsal andpalmar flaps. C, Design of palmar triangular
flaps. a = dorsal flap, b and c = palmar trian-gular flaps.
(Adapted with permission from Dao KD, Wood VE, Billings A:
Treatment of syn-dactyly. Tech Hand Upper Ext Surg
1998;2:166-177.)
Surgical Treatment of Congenital Syndactyly of the Hand
44 Journal of the American Academy of Orthopaedic Surgeons
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dard syndactyly release procedureshould be used to release these
web-bings early (by 6 months), followedby closure of the central
defect and
release of the thumb adduction con-tracture either 6 months
later or at age18 months.39 Release of the thumb ad-duction
contracture and closure of the
central defect may be achieved simul-taneously with either the
Snow andLittler technique35,40 (Fig. 8) or the Mi-ura and
Komada35,41 procedure.
Central PolydactylyCentral polydactyly, or polysyn-
dactyly, involves polydactyly of theindex, long, and ring
fingers in asso-ciation with a complex syndactyly.The ring finger
is the most common-ly duplicated digit,42 and most casesinvolve
duplication of a digit that hasnormal components (eg, type II
poly-dactyly in the Turek and Stelling clas-sifications).39,43
Parents should be warned aboutthe large number of surgeries
requiredfor correction. In one series of 22 pa-tients with central
polydactyly, therewas a total of 160 operations,44 withone patient
requiring 15 procedures.Correction by age 6 months is recom-mended,
especially when both the nor-mal and duplicated digits
articulatewith the same phalanx. It may be nec-essary to create a
more functionalthree-fingered hand rather than riskimpairing
circulation by attemptingto preserve all of the digits. Creatinga
three-fingered hand by sorting outthe jumble of bones in a
polysyndac-tyly often is the best method of treat-ment, requiring
far fewer surgerieswith better functional results.
The surgery itself actually may beeasier to do than a simple
syndactylyrelease because more skin is availablefor closure (Fig.
9). The standard syn-dactyly release is used, and the extrabony
components and soft tissue areresected. Tendons may be
transferredfrom an accessory digit to a retaineddigit to maximize
function. Further-more, parts of two or three digits maybe
transferred to make one function-al finger.
AcrosyndactylyAcrosyndactyly is considered to be
a form of secondary syndactylycaused not by a failure of
differenti-ation but from later in utero damageand fusion of the
damaged terminal
Figure 7 Dorsal (A) and palmar (B) views demonstrating correct
placement of a dorsal trans-positional flap for first web-space
release. (Adapted with permission from Friedman R, WoodVE: The
dorsal transposition flap for congenital contractures of the first
web space: A 20-yearexperience. J Hand Surg [Am]
1997;22:664-670.)
Figure 8 A, Preoperative photograph of a typical cleft hand. B,
The same hand after re-construction with the Snow and Littler
technique. (Reprinted with permission from Dao KD,Wood VE, Billings
A: Treatment of syndactyly. Tech Hand Upper Ext Surg
1998;2:166-177.)
Khiem D. Dao, MD, et al
Vol 12, No 1, January/February 2004 45
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phalanges. It occurs sporadically, isnot hereditary, and may be
termedamniotic disruption sequence. Nowebbing exists proximally
betweenthe adjacent digits; rather, they areseparated proximally by
a fenestra-tion or sinus. When the interconnec-tion between the
digits is only a nar-row skin bridge, it can be simplydivided or
tied off with silk suturesin the newborn nursery. For morecomplex
forms of acrosyndactyly, sur-gical release and reconstruction
mustinclude excision of the sinuses and in-corporation of the
longitudinal cleftin the reconstruction. Despite theFTSG obtained
from the fatty skinprotuberances after their excision anddefatting,
abundant FTSGs still willbe necessary for complete coverage.
Results
Kettelkamp and Flatt6 reported the re-sults of 69 syndactyly
releases in 34patients using a variety of commis-sure designs and
zigzag incisions with
skin grafting. The most important de-terminant of outcome was
age of thepatient at time of surgery, with the bestresults in
patients older than 18 months.The type of commissure design didnot
influence the final outcome.
Posch et al45 reviewed 262 cases,including 340 hands, 558 web
spac-es, and 1,235 sides of fingers. The re-vision surgery rates
(for web creep orflexion contractures) after syndactylyrelease were
higher for border digits(eg, thumbindex finger web, ring-little
finger web) than for long and ringfingers. Revision surgery rates
alsowere higher for releases done beforeage 18 months than for
older patients.45
However, in their review of 218 webreleases in 100 patients,
Percival andSykes46 did not find any statisticallysignificant
differences in the rate ofweb recurrence related to the age ofthe
patient at the time of surgery. Theyreported poorer outcomes in
patientswith concomitant ipsilateral congen-ital hand abnormalities
and in thosewho had split-thickness skin graft rath-er than
FTSG.
Complications
The most common complication insyndactyly release is scar
formationand progression, either at the web oralong the surgical
scar (Fig. 10). Webcreep is eight times more commonwith
split-thickness skin graft thanwith FTSG,25 and it is caused by
acombination of abnormal tissue, sur-gical scar, and increasing
growth ofthe underlying osseous structures.24
It may be inevitable even under op-timal circumstances. If not
corrected,web creep may cause deformity of thegrowing bones and
joints. Parentsshould be advised of this possiblecomplication, and
the patient shouldbe examined periodically through ad-olescence.
Correction requires releaseof the scar, similar to that of the
orig-inal procedure, correction withZ-plasty, and possibly an
additionalskin graft. Web creep may be correct-ed with a four-flap
or three-flap webZ-plasty.
The most serious complication isnecrosis of the digit secondary
to vas-cular compromise. To avoid this di-sastrous complication,
surgeons shouldnever operate on both sides of the
digitsimultaneously. Digital nerve injurymay be repaired primarily
if recog-nized intraoperatively or corrected with
Figure 9 Preoperative photograph (A) and anteroposterior
radiograph (B) of polysyndac-tyly. (Reprinted with permission from
Wood VE: Treatment of central polydactyly. Clin Or-thop
1971;74:196-205.)
Figure 10 An example of web creep. (Re-printed with permission
from Dao KD, WoodVE, Billings A: Treatment of syndactyly. TechHand
Upper Ext Surg 1998;2:166-177.)
Surgical Treatment of Congenital Syndactyly of the Hand
46 Journal of the American Academy of Orthopaedic Surgeons
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secondaryneurorrhaphyornervegraft-ing if identified later.
Summary
Reconstructing a hand with syndac-tyly can be complicated and
isfraught with potential pitfalls. Oncethe anomaly is classified as
simple,
complex, or complicated, the surgi-cal procedures and their
sequenceshould be carefully planned. Con-sideration must be given
to whetherborder digits should be releasedearly, whether skin
grafting isneeded, or whether one fingershould be sacrificed to
produce amore functional, three-fingeredhand. For syndactyly
involving dig-
its of nearly equal lengths, surgeryshould be delayed until age
18months. Associated anomalies andsystemic abnormalities should
beaddressed by appropriate referrals.Careful planning and
meticuloussurgical techniques can minimizepotential errors and
allow satisfac-tory separation of syndactylizeddigits.
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Surgical Treatment of Congenital Syndactyly of the Hand
48 Journal of the American Academy of Orthopaedic Surgeons
AbstractEmbryologyClassificationAssociated ConditionsSurgical
TreatmentSpecial
ConsiderationsResultsComplicationsSummaryReferences