,f tl~e r~bbir. Scand. J.,1979.of pate]lar articular

. perichondrial grafts.~s. Scand. J. plast. Re-

S. H.: Peridmndriatin 26 patients. Scand.1, 1980.uctie met Vrije Peri-Synthetische Hydro-

. Universiteit van Am-

The turnover of adultoint Surg., 51A:1591,

,n from free perichon-g., 29:262, 1976.,hn, S. A.: The patho-tnd. J. Plast. Reconstr.

racheal reconstruction~nd. J. Plast. Reconstr.

.~..: Reconstruccion delnjertos libres de peri-al. Rev. Cuir. Espan.,

. auricular defect withPlast. Reconstr. Surg.,

ration from perichon-.62:507, 1978.).: Perichondrial wristpatients. The Hand,

Regeneration of artic-e perichondrial grafts.ective Tissue, Skin and,ration. 3:49, 1975.~ohn, S. A.: Perichon-*s regeneration. Scand.:3, 1972.ohn, S. A.: The chon-chondrium. Chir. Plas-

: The formation of a~perichondrial grafts.976..: Growth of cartilageaft placed across a de-’last. Reconstr. Surg.,

ds A. R. The regener-e~ joints. Arch. Surg.

, L.: Biosynthesis oflage regenerated from’last. Reconstr. Surg.,

munication., O.: Radiography inichondriat grafts. Acta

Ankilozlarinin Serbest~rimi. GATA Bfilteni,

iska Sjukhuset Uppsala750 14 Uppsala 14

Sweden

The Theory of theTransposition Flap and ItsPractical Application in theHand

GRAHAM LISTER, M.B., F.R.C.S., F.A.C.S.

Associate Clinical Professor of Surgery (Hand), University Louisville, Louisville, Kentucky

LOCAL FLAPS

Local flaps are defined as those derivedfrom tissues immediately adjacent to the pri-mary defect. Consequently, they almostways have a permanent pedicle and can becompleted in one stage. In providing skincover in the hand, local flaps have the follow-ing advantages over free grafts, some ofwhich also make them superior to distantflaps.

Advantages

Blood Supply. Their intrinsic blood suppi[),permits their use to cover bare tendon, ca>tilage, or bone, that is, structures that wouldnot support a free graft or would do so onliyreluctantly and with troublesome adherence(Fig. 1). Such adherence may cause laterproblems in the form of pain, hyperesthesia,or ulceration on a fingertip or by making dif-ficult or unsuccessful subsequent reconstruc-tive procedures beneath the unsatisfactoryskin cover. By using a flap such problems canbe largely avoided. Local flaps, largely be-cause of this blood supply, can be used tobridge defects and smooth contours with littleor no later contracture. Nature abhors a vac-uum, but a sturdy flap can tolerate one. Sucha situation exists in skin defects of the firstweb space, for which local flaps are an idealsolution. In such a situation, free graftswould need to be appfi~d to all the irregular-ities of the space; these~onvo!.utions wouldbe best covered by a meshed spiil>skin grat~t

C̄linics in Plaatic Surgeu--Vol 8, No. 1, January 1981

with a resultant increase in the severity of theinevitable contracture. Likewise, but for dif-ferent reasons, distant flaps impair the firstweb space, their sheer bulk consuming muchof its essential depth.

Sensation. In many eases, the nerve supplycan be transferred in large part intact withthe flap. Even in those situations in which thenerve supply is divided, the recovery of sen-sibility is remarkably good and certainly su-perior to that in skin grafts.8

Skin texture. Being of the hand, local flapsare superior in the matching of skin textureand are more appropriate in the bulk of sub-cutaneous tissue available, being neither toomuch nor too little.

Finally, with local flaps there is little n~edforprolonged immobilization.

" Disadvantages

By contrast, local flaps have the followingdisadvantages:

Limited area. There is a self-evident short-age of skin in the hand, which prevents theuse of local skin to cover large defects. Inaddition, there are regions of the hand thatshould not be used as donor sites, since cov-erage of the resultant secondary defect witha skin graft would be as inappropriate as us-ing the graft on the primary defect. Theseareas are the web spaces and all of the palmarski.n, excepting that part used in fingertip ad-vancement flaps.

Limited mobility a¢~t elasticity. All hand skin

115

Graham Lister116

Figure 1. The merits of immediate flapcover are here illustrated. ,4, This youngpatient had sustained a severe grinder injury tothe dorsum of the small finger with an asso-ciated wound on the ring finger. Immediatereplacement of the extensor apparatus with atendon graft taken from the extensor digitiminimi was only possible provided that im-mediate flap cover was available. B, A trans-position flap has been elevated from the dor-sum of the adjacent ring finger. The secondarydefect was later covered with a full thicknessskin graft taken from the groin. C, The healeddigits have a satisfactory appearance and dem-onstrate full extension. D, Motion has beenmaintained with full flexion. Immediate re-placement of lost extensor apparatus in thedigits is almost mandatory if full function is tobe maintained.

is less mobile because of its deep attachmentsthan that of the abdomen or face and lesselastic owing to its structure, the palmar skinbeing especially so. This means that flaps,however carefully designed, may not readilyundergo the distortion necessary to movethem into the primary defect.

Limited availability. There is virtually no"spare" skin on the hand. The looseness ofthe dorsal skin that is so beguiling in exten-sion disappears entirely in the clenched fist.Some skin, but very little, can be obtained bysuturing under acceptably increased tensionboth in the fingers and in the hand. Thus,advancement and rotation flaps, respectively,are possible, both leaving no secondary de-fects, but only to a very limited degree. Forlarger primary defects it follows that a sec.-ondary defect must be created to be coveredwith a free skin graft as in transposition flapsand larger advancement flaps. The merit,and it is a considerable one, in such local flapstherefore lies in moving the area to begrafted from a site where it is undesirable orimpossible to one where it is acceptable.

Classification

Local flaps are classified as follows:Transposition flaps, in which the flap is raised

from its bed and moved laterally either to a’nimmediately adjacent defect or over a p.enin-sula of intervening skin. When the primarydefect is adjacent-to the flap, design often in-volves triangulation of that defect either infact or in concept, the defect being coveredby closing one of the angles of the triangle,that is, bringing two of the sides of the defecttogether. Such a flap covers the primary de-fect but never the secondary defect in its en-tirety. Grafting of the secondary defect is anecessary additional step in such "triangulated_"transpositions. In other, "nontrianguiated"transpositions the flap does not lie adjacentto the defect along the entire length of theircomn~on edge. Occasionally in such flaps thesecondary defect can be closed directly. Thus,transposition flaps can be conveniently di-vided into triangulated and nontriangulatedvarieties.

Rotation flaps, in which the primary defect

(xY:theoflap,~Rigtuis sh,tioncom~the ]therefrom

s of immediate flapted. A, This young¯ vere grinder injury to! finger with an asso-~g finger. Immediate~sor apparatus with an the extensor digiti,le provided that im-available. B, A trans-levated from the dor-finger. The secondary~ with a full thickness~ groin. C, The healedappearance and dem-D, Motion has been

exion. Immediate re-~sor apparatus in thery if full function is to

as follows:a the flap is raisederally either to ant or over a penin-~rhen the primary7, design often in-t defect either inect being coveredes of the triangle,sides of the defect"s the primary de-fy defect in its en-)ndary defect is ~uch "triangulated""nontriangnlated"~s not lie adjacentire length of theiry in such flaps thesed directly. Thus,: conveniently di-d nontriangulated

he primary defect

Transposition

is triangulated in similar fashion as in a trans-position flap, but it is possible to obtain ~:henecessary amount of skin by suturing the skinedges differentially so that no secondary de-fect remains. In all such rotation flaps theskin that is to cover the defect is contiguouswith it.

Advancement flaps are of two types. In onethe skin is advanced in a V to Y fashion, leav-ing no secondary defect, and in the other theskin is advanced as a rectangular flap, I:henecessary skin availability being achievedeither by flexing the involved digit or by cre-ating a rectangular neurovascular islandthereby leaving at the base of the flap a rec-tangular secondary defect that is subse-quently grafted. The excision of so-calledBurow’s triangles for the purpose ofadvancement has little place in hand surgery.This paper concerns itself with only one ofthese, the transposition flap.

Flaps in the Hand

X

DESIGNING A TRANSPOSITION FLAP

There are two basic tenets regarding trian-gulated transposition flaps, the second andmore important of which applies also to ~:henontriangulated flap.

Selection of the Flap. In the surgeon’splanning the primary defect should be con-sidered to be a triangle. For any triangle, atransposition flap with the shape of a paral-lelogram can be designed, in theory, on anyof the three sides of the triangle (Fig. 2). Oneside of the parallelogram is formed by oneside (XY) of the triangle (XYZ). The second(XW) is created by extending one of the ad-jacent sides of the triangle for a distanceequal, if a strict 1:1 ratio is to be observeff., tothat of the first side chosen. The third side(WV) is parallel and .equal to the first side,and the fourth side forms the base of the flap.

117

Y V pivot point

Z X WI W~ W ~ W4

Figure 2,. To]), This drawing represents a theoreticalskin defect (XYZ) that has equal sides. A transpositionflap is designed on the side (XY), this being the commonborder between the transposition flap and the defect it isto cover. XW is an extension of ZX and equal in length,although this need not be the case unless local conditionsdictate it. WV is drawn parallel to XY and equal to it,thus V becomes the pivot point around which theequilateral parallelogram flap XYWV will rotate to moveinto the defect XYZ. The distance fi’om V to X and itsability to stretch to reach the line V to Z is thereforecritical and is called the "critical line." Bottom, Theamount of stretch demanded of the critical line can bedecreased by widening the flap. Thus, with XW~, which istwice as long as XW~, the amount of lengthening orstretching required in the critical line XV~ is 50 per cent;with W~, which is three times the basic length, thecritical line must stretch by 33 per cent; and with W4,which is four times the basic length, it must stretch by~5 per cent.

There are therefore six possible transpositionflaps for any triangulated defect (Fig. 3, left).The choice is usually made on the basis of thefollowing criteria:

1. Shape of the triangle. Few triangulateddefects prove to be equilateral, one side beingoften significantly shorter than the other two.This reduces the alternatives to two, that is,a flap const.ructed with one or the other ofthe long sides of the triangle as the commonborder between flap and defect (Fig. 3, right).

2. Skin availability. Commonly, skin is not

Figure 3. Left, If the basic defect(XYZ) is an equilateral triangle, there aretheoretically six different transpositionflaps that may be used to cover it.Right, If one side of the primary defectis shorter than the others, the transposi-tion flap is usually designed so that itscommon side with the defect is on one ofthe longer sides of the defect. Thus,there are usually only two flaps to choosefrom in such a circumstance.

V

W

.W

’Y W W X Z W

W

~/ Y V

118 Graham Lister

available for any of the following reasons: an- X x ww

atomic reasons, such as the presence of the ~/nailbed; reasons of the injury sustained; be- _._____../Wcause it is not suitable in texture, as with pal-

Z ....

/mar skin; or because it would inflict a func-tional deficit, for example, in instances inwhich the flap would have to be taken froma web space.

Lengthening of the Critical Line. The pi-vot point of the flap, that is, the point around y Vwhich the flap swings to gain its new position Figure 4. If the demands on the critical line are toois that point (V) at the base of the flap furthest great, they can be reduced by lengthening the flap; thus,from the triangular defect (see Fig. 2). This xw is moved to Xxw~’. This presents some problems incorresponds with the base end of the third suturing the side YXx to YZ, but these can be overcome

CUt in the foregoing description. Thus, if theby incorporating a dog-ear, as illustrated in Figure 5, or bydifferential suturing along the wound. Such lengthening

corner (X) of the flap contralateral to the piv- of the flap, of course, transgresses the 1:1 ratio, andot point is to be moved, as it must be to cover ~andue tension along the critical line will be less wellthe defect, to the far angle of the triangle (Z) .withstood.

that is, the only angle not contiguous with theflap, the skin between the pivot point and thecontralateral corner must stretch to reach tend both side incisions of the flap distallythat far angle. For ease of expression this will -~ away from the base (moving XW to XxWw inbe termed the "critical line" (VX). The Figure 4). This requires making the side ofamount of elasticity required can be realized the flap adjacent to the defect (YXx) consid-by considering the design of an equilateral erably longer than the side (YZ) of the tri-triangular defect with an equilateral trans- angle to which it is to be sutured. This is moreposition flap as in Figure 2. In such a situa- ,of a theoretical than a practical disadvantage,tion the increase in length required in the for the inequality can usually be accommo-critical line that is necessary to transpose the dated by differential suturing or the incor-flap is 75 per cent. With almost any skin this poration of a dog-ear in the flap (Fig. 5).would be impossible and is always so with the Another way of lengthening the flap is toskin of the hand. Certain solutions are avail- ,extend the side incision that is furthest fromable. the primary defect through the pivot point in

MARE THE FLAP W~DER. Considering ’a proximal direction--this is called an exten-again the equilateral design, as one increases :~ion cut (VU in Fig. 6). In the equilateral dia-the width by factors of 2, 3, and 4 (XW~, W~, :gram considered earlier if the line WV wereand W4 in Fig. 2), the amount of expansion ,extended an equal distance to the point ~,required along the critical line (XVz, V~, and ~the new critical line XU would have to beV~ in Fig. 2) falls from 75 per cent to 50, 33, :stretched by only 16 per cent to close the de-and 25 per cent, respectively. Somewhat sur- fect. An extension cut is therefore a highlyprisingly, the latter two are within the elastic ,effective method of increasing the efficiencycapabilities of most skin. -This increase in of a transposition flap. This effectiveness de-width is the simplest means of insuring that creases rapidly as the primary defect nar-a flap is sufficiently mobile, is the method rows--a matter of no concern, as the stan-most commonly used in other parts of the dard transposition flap needs no aid to coverbody, and falls within the general rule that to narrow defects.succeed flaps should be made as large as pos- Making a longer flap means transgressingsible. Unfortunately, in the hand, and espe- the 1:1 rule. Although this can be done safelycially in the finger, it is often impossible to in the hand, in some instances to the point ofmake flaps that much wider, exceeding a 2:1 ratio, it is necessary where

MAXCE THE FLAP LONGER. This is a method possible to take certain precautions.of making the critical line longer without One precaution is to include an arterymoving the pivot point away from the defect within the flap, thereby making it an axialand is the technique most commonly used in .pattern flap. Such arteries include the follow-nontriangulated transposition flaps, rag:

One way of lengthening the flap is to ex- The dorsal digital branch of the proper digital

ita]

then~le:

thegre;phathuzantidigiartepro~teri~sho~opa~

critical line are too~fing the flap; thus,s some problems in,e can be overcome.’d in Figure 5, or by!. Such lengtheningthe 1:1 ratio, ande will be less well

he flap distallyKW to XXWw ining the side of¯ t (YXx) consid-YZ) of the tri-.~d. This is mored disadvantage,y be accommo-g or the incor-tap (Fig. 5).g the flap is tos furthest from~e pivot point incalled an exten-equilateral dia-e line WV wereo the point U,uld have to beto close the de-refore a highlyg the efficiencyffectiveness de-cry defect nar-s-n, as the stan-no aid to cover

~s transgressing,~ be done safelys to the point of~ecessary whereutions.lude an arteryKing it an axiallude the follow-

,he proper digital

Transposition Flaps in the Hand 119

Figure 5. In a flexion contracture o f thethumb, a defect measuring approximately1.4 cm in width has been created on thepalmar surface of the thumb. A dorsaltransposition flap has been designed toclose the defect. A, The flap is in place, andits tip just reaches the far ulnar side of thedefect. This is only achieved by making theflap significantly longer than the width ofthe defect, thus creating a dog-ear, which isclearly seen in this figure. The proximaledge of the wound on the palmar surface oftfie thumb corresponds to line YZ in Figure4, and the contiguous edge of the flapcorresponds to line YXx. B, The flap hasbeen sutured in position after release of thetourniquet, and circulation is good. Thedog-ear is still very evident. C, The dog-earhas disappeared nine months after surgery.Full extension has been achieved.

artery. This arises either from the proper dig-ital artery at the level of the web space andruns along the margin of the lateral band ofthe extensor apparatus or from the dorsalmetacarpal vessel. This artery, according tothe dissections of Johnson and Cohen,4 pro-gresses no further than the proximal inter-phalangeal joint in the fingers, and in thethumb it extends as far as the nail bed. Theseauthors deny the presence of a further dorsaldigital artery arising from the proper digitalartery at the level of the middle phalanx andproceeding to the nail bed (although the ar-teriogram in Figure 83 of their excellent textshows not one but two very suggestive radi-opaque lines). This denial refutes the work

Illustration continued on the following page.

of Joshi~’ ~ and of Flint and Harrison~ whohave published on a flap based on this vessel.Be this as it may, flaps can be here raised withlength:breadth ratios greater than 1:1.

The first dorsal "’interosseous" (metacarpal) ar-tery, ~ which arises from the radial artery justdistal to extensor pollicis longus.

The proper digital artery itself. Although it isthe lifeline of the standard neurovascular is-land flap, this is rarely used in a simple trans-position flap. It is indicated only if no moresimple means of cover is available, if a flap isess6ntial, and if it can be taken from the non-contact side of the digit?

Another precaution is to preserve with un-usual care the venous return. If possible, such

120 Graham Lister

Figure 5. Continued. D, Full flexion is possible withgood local skin on the contact surface of the digit. E, Thesecondary defect, which was covered with full thicknessskiin, has healed well, and the necessary original lengthof the flap is defined by the hyperpigmentation seen inthe skin graft.

flaps should be based proximally with this inmind.

A third precaution is to avoid any torsionor tension in the flap. This requires that thelonger the flap becomes relative to its width,the less should any stretching be demandedalong the critical fine. Thus, a precise mea-surement should be made from the proposedpivot point to the far corner of the defect tobe reproduced in the critical line of the flapwith increasing exactitude as the flap islengthened. This is done most easily using asuture held between two fine hemostats (Fig.7).

MOVE THE PIVOT POINT TOWARD THE DE-vEc’r. This occurs in all flaps simply as a re-sult of their transposition, the pivot pointshifting toward the defect to a degree thatvaries with the laxity of the attachment of theskin to underlying tissue. This freedom ofmovement can be enhanced by underminingthe base of the flap and the skin around thepivot point, but care must be taken not todevascularize the flap or to cause bleedingthat is difficult to control through such lim-ited access. The more formal method of mov-ing the pivot point is to make a back-cut (VT)

Z X W

, /Y

UFigure 6. If on the basic design seen in the top of

Figure 2, the line WV is extended by its own length to apoint U, a new critical line is created. This additionalincision is referred to as an "extension cut" and is one ofthe most efficient ways of decreasing tension in a trans-position flap, since the amount of stretch required in thecritical line UX is approximately 16 per cent as opposed tothe 75.per cent required in the line VX in a transpositionflap of equilateral design throughout. Once again, how-ever, the proportions of the flap exceed the 1:1 length:breadth ratio and again undue tension should be avoidedin closing this flap. In practice, the extension cut wouldbe made progressively until the flap sat comfo.rtably intothe primary defect.

f.t]V

bC~

flf~n~

si

atfl~th

tr

pl

,n is possible with~f the digit. E, Thewith full thicknesstry original length~mentauon seen in

~,n seen in the top ofby its own length to a

±ated. This additionalsion cut" and is one ofing tension in a trans-stretch required in theper cent as opposed to: VX in a transpositionout. Once again, how-~xceed the 1:1 length:sion should be avoidede extension cut wouldtp sat comfortably into

Transposition Flaps in the Hand 121

Figure 7. A, In resurfacing the ulcer overthe proximal interphalangeal joint in a burnscar, increased length was used on the flap, asillustrated in Figure 4, and an extension cut isto be employed. In the presence of suchdemands on the vascularity of the flap, notension whatsoever along the critical lineshould be permitted. For this reason, thedistance from the pivot point to the far comerof the flap, the critical line, is made exactlyequal to the distance from the pivot point tothe far side of the defect. This is illustratedinB andC, where a fine suture between hemo-stats is employed to guarantee that this dis-tance is equal.

from the pivot point along the fourth side ofthe parallelogram (Fig. 8). From a vascularviewpoint, this procedure has an effect simi-lar to that of making, the flap longer, in thatit increases the ratio of the length to tlhebreadth of the base of the flap. The back-cutcan be performed after transposition of theflap or before. After transposition, the per-formance of a back-cut is an invaluable ma-neuver in relaxing tension in a flap that showssigns of vascular embarrassment, usually inthe form of areas of pallor. As in other situ-ations, such as the volar VY advancementflap, the less experienced surgeon may fearthat the circulation is inadequate because .ofexcessive mobilization, whereas the contrary istrue. Inadequate mobilization with resultantexcessive tension causes many more vascularproblems with flaps in the hand than does

Z X W

/¥ r v

Figure 8. A back-cut on the basic design shown at thetop of Figure 2. A back-cut (VT) appreciably decreasesthe tension that will be required in the critical line,moving the pivot point nearer to point Z. This procedurecan be done as a primary element in the design or,alternatively, can be done to "rescue" a flap that showsproblems in transposition. The length-breadth ratio onceagain exceeds 1:1 because the breadth of the base of theflap has been narrowed. This is, however, preferable toincreasing the tension along the critical line. (SeeFigures 9 and 14.)

122

excessive mobilization. This can be well illus-trated in the situation here considered (Fig.9).

In the face of a transposition flap that be-comes partially avascular when sutured inplace, if the surgeon incises from the pivotpoint part way along the base, an improve-ment in circulation will invariably be noted.Thus encouraged, the surgeon will find him-self or herself using this maneuver with in-creasing frequency and to a greater degree,with good effect. While making such a reliev-ing incision in the skin--best done underloupe magnification--the surgeon may en-counter vessels or nerves in the subcutaneoustissue that may be preserved with benefit bygently spreading the skin edges apart withdissecting scissors. The tension is relieved byincising the skin, not the subcutaneous tissue.If such a back-cut is made formally as part ofthe flap design, the longer it becomes, themore the outline becomes that of aflagflap(Fig. 10). The flag flap, as described Vilain, 9 consists of the dorsal skin from themiddle phalanx, the staff or pole being a nar-row pedicle of skin taken from the dorsolat-eral border of the proximal phalanx. Thenarrow pedicle greatly increases the mobilityof the flap, and its survival is guaranteed ifa vessel can be incorporated in the staff.

Such a vessel exists for a flap of the dorsalskin of the proximal phalanx (Fig. 11). thatbeing the dorsal digital artery, arising fromthe proper digital or the dorsal metacarpalartery. The veins are also well located in thatregion passing as they do to either side of themetacarpophalangeal joint. Thus, a robustaxial pattern flap of considerable size, in theadult hand a maximum of 10 square cm, canbe raised on a very narrow pedicle or even asan island, with the potential to cover a defectof like dimension (Fig. 12) in one of the fol-lowing areas:

1. On the palmar surface of the donordigit from the middle digital crease to thedistal palmar crease.

2. On the digit adjacent to the pedicle ofthe flap on the palmar surface over a similararea and on the dorsal side of that digit outto and including the proximal interphalan-gealjoint (Fig. 13).

3. Over the dorsal aspect of the metacar-pophalangeal joint of either of the two digits.

When considering such a flap to cover apalmar defect, the surgeon should bewarethat the primary injury did not damage thevascular pediele and would be well advised to

Graham Lister

dissect out the relevant digital artery beforeraising the flap.

RAISING AND APPLYING ATRANSPOSITION FLAP

Bearing the previously discussed consid-erations in mind, the surgeon should in themind’s eye or with a marking pencil trian-gulate the defect to be covered. In the trau-matic defect there is no need whatsoever toformally excise a triangular area. Routinewound excision for debridement is all that isrequired, for the natural skin elasticity willcause the flap to conform to minor irregular-ities in the defect. Usually the triangle hasone side shorter than the others, and in thatsituation the parallelogram of the flap shouldlie adjacent to one of the long sides of thetriangle. The choice between these two po-tential flaps is made on the basis of skin avail-ability, as already discussed. If the defect ap-proaches an equilateral triangle, the surgeonmust decide how to alleviate excessive tensionalong the critical line on the basis of the po-sition of the flap and the relationship of theselected base to known vessels. The choicesare, as stated earlier, a wide flap, a long flap,an extension cut, or a back-cut in the base ofthe flap at the pivot point.

All flaps on the dorsum of the hand shouldbe raised just superficial to the paratenon,leaving it behind as a very satisfactory bed onwhich to place a graft. The flap confined tothe dorsum should lift with ease, requiri,ngonly gentle strokes with the knife blade toease its points of maximal tension. If a flapraised on a finger extends onto the side ofthe digit, dissection will be arrested by thestrong skin ligaments. This skin anchoragesystem, as Landsmeer7 calls it in his exhaus-tive study of the subject, is complex, but itcan be simplified into the ligaments ofCleland and of Grayson. The former lies dor-sal to the neurovascular bundle, is best de-veloped on the lateral aspects of the interpha-langeal joints, and passes in a lateral-palmardirection to attach firmly to the skin. Gray-son’s ligament is less well developed than Cle-land’s, lies on the palmar aspect of the neu-rovascular bundle, and passes in a transversemanner from the fibrous flexor tendonsheath to the skin. In raising certain trans-position flaps the surgeon can materially en-hance their mobility and therefore their vas-

cry b£fore

~d consid-uld in thencil trian-~ the trau-ttsoever tot. Routine~ all that is,~sticity willirregular-iangle hastnd in thatlap shoulddes of the~e two po-skin avail-defect ap-le surgeonive tensionof the po-

ship of thehe choicest long flap,the base of

and shouldparatenon,ory bed on:onfined to¯ requiringe blade toa. If a flapthe side ofted by theanchorage

iris exhaus-)lex, but itaments of~er lies dor-is best de-e interpha-~ral-palmarskin. Gray-d thma Cle-ar the neu-t transverseor tendontrain trans-tterially en-e their vas-

Transposition Flaps in the Hand 123

Figure 9. A, A defect is seen on the radial aspect of the index finger, a primary nerve graft having been placed in asharply cut defect of the radial digital nerve. This area of skin loss is one of the more difficult to cover. B, A transpositionflap has been designed on the dorsum of the digit, which on transposition (C) can be seen to create a significant dog-ear atthe proximal end of the primary defect. D, After the flap is sutured into position and the secondary defect has beengrafted, the dog-ear is still evident. E, The tip of the flap can be seen to be somewhat avascular at the far side of theprimary defect, that is, point Z in Figures 2, 4, 6, and 8. F, This avascularity is even more pronounced on flexion of thedigit. G and H, Full healing was achieved with a return of full rnotion to the digit. On examiningC, D, andE it can be seenthat the tension across this flap, which is not too great, could have been completely relieved by the employment of anextension or back-cut.

124 Graham Lister

Figure 10. If the back-cut is extendedeven further across the base of the trans-position flap, the design approaches that ofthe flag flap. The original French design, asdescribed by Vilain, incorporated a staff inthe flag flap and was designed primarily onthe middle phalanx of the digit. There is anaxial modification of the flag flap that in-corporates the dorsal digital artery and isbest constructed on the proximal phalanx.

French Original Axial Modification

Figure 11. The dorsal digital arterymay arise either from the proximaldigital artery or from the dorsal interos-seous or metacarpal artery.

Figure 12. A, An axial flag flap, such asthat described in Figure 11, can be trans-posed from the dorsum of the middlefinger to the dorsum of the index or to thedorsu~n of either the middle or the indexfinger over the region of the metacarpo-phalangeal joint. B, It can also be rotatedaround to cover the palmar aspect of themiddle or index fingers. If such a defectexists on the palmar surface, particularly ofthe donor digit, care should be taken toinsure that the artery has not been damagedby the original injury. The distal margin ofthe flap in both A and B is marked with anX, and the position that the distal marginadopts in the various defects is indicated bythe same marking.

cut is extendedse of the trans-?roaches that ofrench des!gn, as)rated a staff in,ed primarily onligit. There is anlag flap that in-al artery and is)ximal phalanx.

flag flap, such as1, can be trans-of the middle

e index or to thedle or the indexthe metacarpo-

~ also be rotated~ar aspect of theIf such a defecte, particularly of,uld be taken toot been damaged¯ distal margin of~ marked with anhe distal marginzts is indicated by

Transposition Flaps in the Hand 125

Figure 13. Application of an axial flag flap is illustrated. A, Following a severe crushing injury to the index finger,this patient presented with loss of skin on the palmar and ulnar aspects of that digit together with exposure of theproximal interphalangeal joint. B, The axial flag flap ha.,; been incised on all four margins leaving only a small skinbridge overlying the dorsal digital artery. The tourniquet has just been released, and refill of the flap can be clearly seen.C and D, The flap is shown in position and can be seen to cover the ulnar aspect and a portion of the palmar aspectof the proximal phalanx and the proximal interphalangealjoint. Such a closed flap could not be achieved by any othermeans. The patient went on to show uneventful healing, although developing fairly severe posttraumatic osteoarthritisof the proximal interphalangeal joint.

cularity by dividing these skin anchors. It isimportant to appreciate their relationship tothe neurovascular bundle and the fact that,in flaps based on the side of the digit, thevessels supplying the flap must pass throughCleland’s ligament. To protect these vesselsand the main bundle, the ligament should bedivided hard against the skeleton, again using aknife. The further away from the skeletonthis incision is made, the more likely is vas-cular injury.

The flap can now be transposed into theprimary defect. The sequence of events inmoving a transposition flap follows a set pat-tern.

1. Define the primary defect, insuring thatits margins and floor are viable and surgicallyclean. The defect should be made, by posi-tioning of the digits, as large as possible. Inthis way the proper amount of skin is intro-duced to meet all requirements, and the con-figuration of the defect can better accom-modate a wide, vascularly secure flap. These

considerations are, of course, of particularsignificance in the web space.

2. Determine the site of maximum tissueavailability.

3. Mark out the base of the proposed flap.4. Measure from the pivot point to the far

point of the defect and transfer that mea-surement to the length of the flap from pivotpoint to tip.

5. Consider whether the length:breadthratio of the proposed flap is acceptable. Ifnot, redesign the flap with a wider base; if itis, proceed to the next step.

6. Raise and transpose the flap.If all previous planning has been correct

this should be achieved with relative ease.Remember that the flap will be the more dif-ficult to move the thicker or more rigid is theskiff. Thus, palmar skin or edematous skinwill move with more reluctance. If, despitethese considerations, the surgeon feels thattoo much traction is being applied or indeedno reasonable traction carries the flap over

126

the defect, he or she must make appropriateadjustments (Fig. 14). No flap dragged un-willingly into position works efficiently--nothing does. What steps can be taken?Those concerned with the basic design of theflap, length and breadth, are forever goneand reconsidering the design will serve tohelp only future patients. There are six pro-cedures open to the surgeon in this predica-ment.

1. Reconsider the needs of skin cover. Theindications for the transposition flap mayhave been relative, concerned more witheventual function than immediate needs. Tln~eapplication of a free skin graft may then bethe correct defense and is usually pursuedwith some reflection on why the more adven-turesome gambit of the transposition flap hadever been chosen for an opening.

2. Undermining the flap base and piw)t

Graham Lister

point. This gives limited gain and has the dis-advantages ah-eady mentioned.

3. The back-cut, already discussed atlength, is an incision across the base of theflap on the side away from the defect thatmoves the pivot point closer thereto and canoften save the day. The cut is extended mil-limeter by millimeter until the flap fits, withpreservation of the subcutaneous tissues andthe neurovascular structures they contain ifsuch preservation does not nullify the release.Hesitation at this juncture serves no purposeif the surgeon’s judgment has been good withrespect to skin cover indications, that is, theprimary defect needs a flap, and the second-ary defect can take a skin graft. It follows thatthe back-cut can be as bold as necessary, forthe gamble is made with stakes that can atworst be lost without tragedy. But loss is rare,unless the original design was quite wrong.

g~fla

wb

tioviea~sit~th~

coed

re(inpr.mi

Figure 14. This patient, operated upon some years ago, illustrates the hazards of adhering rigidly to set rules. A defecton the radial aspect of the index finger that exposed the proximal interphalangealjoint was covered with a transpositionflap that employed much of the dorsal surface of the finger. The 1 : 1 ratio was carefully observed, and the distance fromthe pivot point to the far edge of the defect was made to equal almost exactly the critical line of the chosen transpositionflap. A, Despite this care, it can be seen that extensive creasing across the flap has seriously jeopardized its vascularity.B, This is clearly shown by the relative avascularity of the tip of the flap, which overlies the exposed proximal inter-phalangealjoint. The entire design could have been made somewhat smaller, and certainly safer fi-om a vascular point ofview, by the employment of an extension cut or a back-,~ut. SuCh incisions would have relieved the lines of tension in thisflap, thereby permitting good blood supply from the remaining base of the flap. This case also illustrates the need forcare in transposition flap design when the flap is to pass around the convex surface of the cylindrical digit. The dis-tances involved are significantly greater than one might first expect. The fact that the flap survived in its entirety withfull function of the digit (C and D) is more testimony to the healing powers of the patient than to the design skills the surgeon.

nd has the dis-

¯ discussed athe base of thehe defect thataereto and canextended nail-

_" flap fits, with~)us tissues andthey contain iflify the release.yes no purposebeen good withms, that is, thend the second-. It follows that~ necessary, forkes that can atBut loss is rare,¯ quite wrong.

to set rules. A defectwith a transposition

~d the distance fromchosen transpositiondized its vascularity.)sed proximal inter-m a vascular point ofnes of tension in this~strates the need fortrical digit. The dis-¯ d in its entirety witho the design skills of

Transposition Flaps in the Hand

4. Raise another flap. To admit an errortakes rare courage. If it is clear that the flapwill not make it to the defect and the indi-cations were correct, despite all that is writtenin the preceding paragraph, the first flapshould be preserved, either to partly coverthe defect--a clumsy solution at best--or tobe returned to the bed from which it wasraised. The second flap may be local, re-gional, or even distant. It is for this eventu-ality that the wise surgeon obtains informedconsent for all possible procedures.

5. Add a free skin graft. Part of the pri-mary defect may be suitable for free skingrafting. In such a case the combination offlap and graft may achieve the first goal,which is viable skin cover. Nonetheless, thesurgeon will recognize that such a combina-tion may be unsatisfactory from the point ofview of wound healing--a free graft besidea flap over a traumatic defect is not an idealsituation since (1) wound effusions beneaththe graft cannot be efficiently controlled bya firm bolus dressing, which perforce lifts theedge of the flap, creating a dead space be-neath both flap and graft, and (2) the graftcannot easily be made to conform with thecontours of the bed and still meet with theedge of the flap. The combination is also un-satisfactory from the point of view of futurereconstruction and aesthetic appearance, notin the restricted sense of modern cosmeticpractice, but in the broader sense, whichmight be termed--hopefully without hubris--surgical elegance.

6. Return the flap to its bed for later use.This is mentioned only to be condemned, notoutright, but with only rare reservations¯ Todo so, first of all, leaves the primary defectuncovered--this may lead to desiccation anddeath of vital structures, to unwanted gran-ulation and resultant fibrosis, or to the de-velopment of infection. Second, to do socauses the flap to become more stiff and lessmobile. A delayed flap is certainly more re-sistant to vascular compromise but also,through edema in its substance and fibrosison its undersurface, is much less pliable.

In the great majority of cases, the flap willfit. If the raising has been performed undertO.urniquet, this should now be released. Anyv~gorous bleeding should be controlled, buttime should be allowed to play its valuablerole. While the reactive hyperemia settles, thesurgeon can take the appropriate graft withwhich to cover the secondary defect. Theconsiderations of bed and function that usu-

127

ally dictate the choice between full- and split-thickness skin should apply here. Once he-mostasis has been achieved by time and ju-dicious cautery, the flap should be suturedinto position. The graft should then be ap-plied to the secondary defect with applicationof a bolus dressing where appropriate. Thesurgeon should now check the mobility of thejoints adjacent to the flap, observing the ef-fect on both the flap circulation and also onthe .position of the skin graft on its bed. Fourto six days of immobilization are beneficial tothe wound and do no harm to the joints, butmotion thereafter is mandatory.

CONCLUSION

This paper is concerned entirely with theprinciples underlying the design of transpo-sition flaps to cover skin defects. Many ofthese principles, having regard to skin avail-ability, the pivot point, the critical line, exten-sion and back-cuts, and the avoidance of un-due tension, apply to all local and regionalflap~ in the hand and can be extrapolated tothem with benefit.

REFERENCES

1. Beasley, R. W.: Principles and techniques of resur-facing operations for hand surgery. Surg. Clin. NorthAm., 47:389-413, 1967.

2. Flint, M. H., and Harrison, S. H.: A local neurovas-cular flap to repair loss of the digital pulp. Br. J. Plast.Surg., 18:156-163, 1965.

3. Foucher, G., and Braun, J. B.: A new island flaptransfer from the dorst~m of the index to the thumb.Plast. Reconstr. Surg., 63:344-349, 1979.

4. Johnson, M. K., and Cohen, M. J.: The Hand Atlas.Springfield, Illinois, Charles C Thomas, 1975.

5¯ Joshi, B. B.: Dorsolateral flap from same finger torelieve flexion contracture. Plast. Reconstr. Surg.,49:186-189, 1972.

6. Joshi, B. B.: A local dorsolateral island flap for res-toration of sensation after avulsion injury of fingertippulp. Plast. Reconstr. Surg., 54:175-182, 1974.

7. I~andsmeer, J. M. F.: Atlas of Anatomy of the Hand.London, Churchill Livingstone, 1976.

8. Porter, R. W.: Functional assessment of transplantedsldn in volar defects of the digits. J. Bone Joint Surg.,50A:955r963, 1968.

9. Vilain, R., and Dupuis, J. F.: Use of the flag flap forcoverageof a small area on a finger or the palm. Plast.Reconstr. Surg., 51:397-401, 1973.

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