2004 - Surgical Treatment of Congenital Syndactyly of the Hand

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

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-


40 Journal of the American Academy of Orthopaedic Surgeons

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


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.)



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.)



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.)



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.)



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.)



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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ment of syndactyly, in Littler JW, Cram-er LM, Smith JW (eds): Symposium onReconstructive Hand Surgery. St. Louis,MO: CV Mosby, 1974, vol 9, pp 144-156.

2. Temtamy SA, McKusick VA: The genet-ics of hand malformations. Birth DefectsOrig Artic Ser 1978;14:1-619.

3. Capek L, Khouri RK: Principles of syn-dactyly surgery. Contemp Orthop 1995;30:101-105.

4. MacCollum DW: Webbed fingers. SurgGynecol Obstet 1940;71:782-789.

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2004 - Surgical Treatment of Congenital Syndactyly of the Hand