The Z-plasty

The Z-plasty is a procedure which involvesthe transposition of two interdigitating triangu­lar flaps. The name derives from the 'Z' shapeseen when the three limbs of the flaps are drawnout on the skin. Transposition of the flaps hasseveral effects (Fig. 2.D, of which two havespecial relevance:

1. There is a gain in length along the direction ofthe common limb of the Z.

2. The direction of the common limb of the Z ischanged.

Exploitation of these effects has made the Z­plasty an extremely useful and widely usedprocedure. Its value has been most strikingly

2

established in three sets of circumstances: inthe treatment of contracted scars, when use ismade of the gain in length, in the managementof facial scars, when use is made of the changein direction of the common limb, and in theprevention of scar contracture in certain types ofelective and emergency surgery, particularly inthe hand. This latter usage is discussed inChapter 11.

Lengthening and change of direction of thecommon limb occur together as a result oftransposition, but it is usually only one of thetwo which concerns the surgeon at any particu­lar time. The fact that the other is accomplishedat the same time is usually a bonus, though it canbe a nuisance.

Fig. 2.1 The Z-plasty.

2\

22 FUNDAMENTAL TECHNIQUES OF PLASTIC SURGERY

THEORETICAL BASIS

The Z-plasty was originally used in releasingcontracted scars, and its theoretical basis can bemore easily understood if it is considered withthat as the background.

The basic manoeuvreWhen the Z-plasty is used to release a contrac­ture, the common limb, i.e. the central limb of theZ, is positioned along the line of the contracture.The size of each of the angles of the Z is 60°, acompromise figure which has been reached as aresult of experience. The reasons for selectingthis angle size and the effects of altering it arediscussed later, but 60° will be the size used inthe present discussion.

Constructed in this way the two trianglestogether have the shape of a parallelogram withits shorter diagonal in the line of the contracture,its longer diagonal perpendicular to it. Thetwo diagonals can conveniently be referred toas the contractural diagonal and the transversediagonal (Fig. 2.2).

In order to understand the sequence of eventswhen a Z-plasty is used in releasing a contrac­ture it is essential to bear in mind that the com­mon limb of the Z, being along the line of thecontracture, is under tension. Its ends springapart when the interdigitating flaps are raisedand the fibrous tissue band responsible forthe contracture is divided. The springing apart ofthe divided contracture results in a change in the

Transverss 11.... ,c :~

0"O .,

shape of the parallelogram, and the triangularflaps become transposed, the contracturaldiagonal lengthens and the transverse diagonalshortens (Fig. 2.3).

It is important to appreciate that when a Z-plastyis used properly to correct a linear contracture thesurgeon does not actively transpose the Z flaps. Flaptransposition follows naturally from the change inshape of the parallelogram, as do the lengtl1ening andtheshortening.

The changes in length are such that the lengthof the contractural diagonal after transpositionequals that of the transverse diagonal beforetransposition. The contractural diagonal haslengthened at the expense of the transversediagonal, which has shortened as much as thecontractural diagonal has lengthened.

Translated into practical terms this means thatskin has been brought in from the sides with atightening effect, as shown by the shortening ofthe transverse diagonal, to allow the lengtheningof the contractural diagonal. The difference inlength of the two diagonals indicates the actualamount of lengthening and shortening.

The surgeon's interest is in the lengtheningrather than the shortening, but it is crucial to suc­cessful Z-plasty practice to realise that lengthen­ing cannot take place without the transverseshortening. Translated into practical terms, thismeans that unless there is transverse skin slackavailable, equal in quantity to the length differ­ence between the axes of the Z, the method willnot work.

Transverse :}DiaQI)naIJ<ii:;

~coo

Fig. 2.2 The diagonals of the Z-plasty.showing how, with transposition of the Z-plasty flaps. the contractural diagonal is lengthened andthe transverse diagonal is shortened.

THE Z-PLASTY 1J

1

2

/I

II

I

III\\\\\,

4

Fig. 2.3 The several stages of the Z-plasty, demonstrating how division of the contracture, shown diagrammatically as a single band. hasthe effect of changing the shape of the Z, lengthening the contractural diagonal and shortening the transverse diagonal.

Variables in constructionSince the skin flaps must fit together in theirtransposed position, the limbs of the Z are con­structed equal in length. The angles of the Z arealso usually made equal in size. The factorswhich do vary are angle size and limb length,and the ways in which variation in these factorsaffects the result provide an explanation of whyspecific constructions are used in particular setsof circumstances.

Angle size. Once the lengths of the limbs of theZ have been fixed the amount of lengthening tobe expected is determined by the size of theangle, its amount increasing with increase in thesize of the angle. With an angle of 30° there istheoretically a 25% increase in the originallength, with 45° a 50% increase, and with anangle of 60° the increase rises to 75% (Fig. 2.4).

These increases are theoretical and they cannotbe applied with strict accuracy to the clinicalsituation, though when account is taken of

1Z-~Zl2~Anglesize 300 450 600

---Increaselj'l5'/~-- - - -­

in length

- --------- -------- -

Fig. 2.4 The changes in the percentage increase of length whichresults from the use of different angle sizes.

24 FUNDAMENTAL TECHNIQUES OF PLASTIC SURGERY

Fig. 2.S Comparison of the lengthening and shortening pro­duced by a single and a multiple Z-plasty. Note also how lateraltension is concentrated by the single Z-plasty and diffused by themultiple Z-plasty.

Lateraltension

'~{ diffused

)~'

>;~'

1!~"

Multiple Z-plasty

Lengthening, 2cmShortening, a.5cm

Scale1cm~

Lengthening, 2cmShortening, 2cm

Single Z-plasty

Lateraltensionconcentrated

the point of view of lengthening and shortening(Fig. 2.5).

The single Z-plasty achieves 2 em of lengthen­ing and at the same time there is 2 em of shorten­ing in the transverse axis.

In the multiple Z-plasty, each of the four Z­pla sties achieves 0.5 em of lengthening with acorresponding 0.5 em of shortening at eachtransverse axis. The lengthening which occurs isin series and consequently is additive, giving anoverall lengthening of 2 em, while the shorteningis in parallel, and remains 0.5 em at each Z. Theamount of lengthening achieved by each is thusthe same, but the shortening has been greatlyreduced by the use of the multiple Z-plasty. Manyclinical situations exist where a Z-plasty couldbe used to advantage, but the tissues cannotstand 2 em of shortening, though they could tole­rate 0.5 em with ease, and for these the multipleZ-plasty is a possible solution.

The change from single to multiple Z-plastyalso alters the form of the lateral tension. Frombeing concentrated in the line of the transverse

variations in skin extensibility, pre-existing scar­ring, etc., it is surprising how well they do apply.The theoretical lengthening usually exceedsslightly what can be achieved in practice.

In releasing a contracture the object of the Z­piasty is to maximise the amount of lengthening.Narrowing the angle much below 60° woulddefeat this object, since the smaller anglewould reduce the gain in length, and adverselyinfluence the blood supply of the flaps.

Increase in angle size much beyond 60°would increase the amount of lengthening, butit would also entail an equal increase in theamount of transverse shortening. Tissue fortransverse shortening is seldom available inunlimited quantity, and it is found in practicethat when the angle increases beyond 60° thetension produced in the surrounding tissuestends to be so great that the flaps cannot read­ily be brought into their transposed position.For this reason 60° is the compromise figureused for angle size.

Limb length. With the use of 60° as the routineZ-plasty angle, it is length of limb which pro­vides the major variable in practice. The amountof tissue available on either side determines thepracticable limb length - a large amount permitsa large Z, a small amount correspondingly limitsthe size of the Z.

Single and multiple Z-plastyThe search for ways of reducing the amount oftransverse shortening without significantlyaffecting the amount of lengthening has led tothe development of the multiple Z-plasty, and itsadvantages are such that it has replaced thesingle Z-plasty in many clinical situations.

In the single Z-plasty one large Z extendsalong virtually the entire length of the contrac­ture; in the multiple Z-plasty the contracture isviewed as having a number of segments, on eachof which a small Z-plasty is constructed.

The contrast between the two types of Z-plastycan best be appreciated by using a concreteexample. If we construct a single Z-plasty whichis going to achieve 2 em of lengthening, andat the same time construct a series of foursmall Z-plasties, each equal in size to a quarter ofthe single Z-plasty, they can be compared from

THE Z·PLASTY 25

Fig. 2.6 The modified shape of the Z.plasty flaps which givesmaximum vascularcapacity.

limb of the single Z, it is spread over the severaltransverse limbs of the multiple Z-plasty inaddition to being reduced. These differenceshave obvious advantages from a vascular pointof view.

In the multiple Z-plasty, as in the single Z­plasty, the theoretical lengthening is probablyunattainable. Quite apart from the effect ofscarring, etc., there tends to be some loss ofleng thening in passage from one Z to thenext. Nevertheless the comparison betweenthe two, and the advantages of the multiple overthe single, are still valid.

is usually an indication of this fact. The singleZ-plasty, with its large flaps, is more prone tothis problem, since it concentrates transversetension; the smaller flaps of the multiple Z-plastyare less liable, since their effect is to reduce anddiffuse the transverse tension, thereby minimis­ing circulatory embarrassment.

CLINICAL USAGE

The Z-plasty is used in different clinical situa­tions, in some of which the theoretical basis ofthe procedure is not immediately obvious, but ineach one analysis of the changes which takeplace with transposition of the flaps is capable ofexplaining the effect of the change in terms oflengthening and shortening, or of a change in thedirection of the common limb.

Use in contraduresFrom the theoretical discussion it follows thatthe Z-plasty is most effective where the contrac­ture is narrow and the surrounding tissuesare reasonably lax. Scarred and contracted tis­sue on either side can yield no 'slack' to allowlengthening, which explains why the postburncontracture is so seldom totally correctable by aZ-plasty, single or multiple. In contracting,the burn scar contracts in all directions simultan­eously, and although a contracture may be pres­ent clinically, skin has actually been lost inevery axis. The contractural axis is only the mostobviously tight. The transverse axis is just asshort and it is unable to shorten any furtherin the way that would be needed for a successfulZ-plasty.

Ideally, the central limb of the Z should extendthe full length of the contracture but this requiresa correspondingly large quantity of tissue to bebrought in from the sides, tissue which is notalways available. The problem arises in the limbsparticularly, for such tissue as is available tendsto be spread out along the length of the limbrather than being concentrated at one point. Ashas been discussed above, the solution in suchcircumstances is likely to lie in constructing amultiple Z-plasty rather than a single Z-plasty,bringing in from the sides smaller quantities of

Shapemodified tobroaden the tipof each flap

Standard shapeof the flaps

Blood supply of the flapsThe most frequent complication of a Z-plastyis necrosis of the tip of a flap and it is a particu­lar hazard when there is scarring of the skin or,more commonly, when the skin flap raised has tobe excessively thin, e.g. in Dupuytren's contrac­ture involving the finger, a problem discussed ingreater detail on p. 194. Precautions to avoidnecrosis can be taken at all stages of the proced­ure - by providing the flaps with the maximumof vascular capacity, and by avoiding tension.

Provision of maximum vascular capacity. This isachieved by designing the flaps broad at the tip,by cutting the flaps as thick as possible, and byavoiding scarring across the base. The tip of theflap can be broadened by modifying its shapeslightly without affecting its angle size (Fig. 2.6).The thickest flap practicable should always becut, making use of the levels of underminingdescribed on p. 10.

Avoidance of undue tension. Tension in thetransposed flaps can be very difficult to avoid,particularly when the contracture is a dubiouscandidate for a Z-plasty. Indeed its presence

26 FUNDAMENTAL TECHNIQUES OF PLASTIC SURGERY

tissue along the entire length of the contracture(Fig. 2.5).

A good measure of the planning and executionof a Z-plasty is the behaviour of the flaps whenthe contracture is released. If the manoeuvre hasbeen well planned and carried out the flapsshould literally fall into their transposedposition. Indeed it should be difficult to returnthem to their old relationship.

The Z-plasty, single or multiple, is most effect­ive when the contracture is of the bowstringtype. When the contracture is more diffuse it isless satisfactory, and a stage is eventually reachedwhere the decision has to be made whether a Z­plasty is appropriate at all, or whether fresh skinshould be imported from elsewhere in the form ofa free skin graft or flap. The answer is usually tobe found in the surrounding skin; transverse slackmust be present if the contracture is to be releasedand if it is not obviously available there (Fig. 2.7)the Z-plasty will fail.

Planning theZ-plasty (Figs 2.8, 2.9)It may be difficult in planning the procedure todecide where the flaps should be. A goodmethod is to draw an equilateral triangle on eachside of the contracture (see Fig. 11.6), and toselect the more suitable of the two sets of limbsfrom the resulting parallelogram. If neither hasany demonstrable advantage either may be used.

Factors which might favour one set are:

1. The flap with the better blood supply ispreferable. In particular a potential flap withscarring across the base should be avoided.

2. One flap may result in a scar which will fallinto a better line cosmetically. The factorswhich would influence the choice in suchcircumstances have already been discussedin Chapter 1.

3. The lie of the flaps and the surrounding skinmay permit one set of flaps to transpose morereadily into their new position.

Fig. 2.7 A narrow axillary contracture (A), suitable for correction by a Z-plasty. and a diffuse axillary contracture (8), unsuitable fora Z plasty,and requiring for its correction the insertion of a split skin graft.

THEZ.PLASTY 27

~/I.

/\.!. '\J ~/

Fig.2.8 The use of a singleZ-plasty to correct the neck webbing component ofTurner's syndrome.

Fig. 2.9 The use of a multiple Z-plasty in correcting a localised postburn contracture of the neck.

Skin which shows scarring has lost some ofits normal elasticity and this may affect theplanning of the flaps. A flap of scarred skinshould be designed a little longer initially thanits fellow of normal skin, otherwise the scarredflap will be found to be too short when it issutured to the unscarred flap.

It is usual, although not essential, to have thetwo angles of equal size. On occasion a line

of scarring can limit the angle of one flap anddissimilar angles may then have to be used.Lengthening and shortening then become theaverage of the amount to be expected from eachangle alone. Indeed, if the full quadrilateral ofany Z-plasty is drawn, complete with contrac­tural and transverse diagonals, the transverse diago­nal will provide an indication of the actual lengthto be expected when the flaps are transposed.

28 FUNDAMENTAL TECHNIQUES OF PLASTIC SURGERY

Use in facial scarsScars in the face tend to be more cosmeticallyacceptable the more nearly they lie in a line ofelection, and a problem of acceptability can arisewhen an otherwise satisfactory scar is more than30° off the line of election. When a Z-plasty isused to improve the appearance of a scar, itseffect as a rule is to break the line of the scar andchange its direction. This change in directioninvolves the common limb of the Z-plasty, andthe object is to place it postoperatively as nearlyas possible in a line of election.

The success of the method used to place thecommon limb of the completed Z-plasty accu­rately in terms of size, site, and directiondepends on two facts. First, if the Z-plasty inci­sions are made to end on the selected transverseline, transposition of the flaps will leave thecommon limb lying along the line as planned(Fig. 2.11). Second, the limbs of the Z-plasty areequal in length.

The planning of the Z-plasty used for this pur­pose must be regarded as a formal procedure,marked out carefully on the skin with Bonney'sBlue before any actual incision is made. Thesteps themselves are more easily illustrated thandescribed (Figs 2.11,2.12).

With the scar outlined (1), the line, preferablyin a line of election, is selected for the postopera­tive common limb, and drawn out on the skin(2). The length of the intended common limb,which determines the size of the Z-plasty, ismeasured out on the line of the scar, propor­tioned approximately evenly on each side of theline already selected and drawn out as the post­operative common limb (3). From each extremityof this measured length, a line of equal length ismarked out to meet the line drawn out to repre­sent the postoperative common limb (4). Thesesteps outline the Z-plasty flaps (5). The fact thatthe two oblique lines have been made to end onthe selected transverse line means that transposi­tion of the flaps will bring the common limb intothe desired line as planned, regardless of itsdirection (6).

Altering the obliquity of the line selected forthe postoperative common limb has the effect ofaltering the size of the Z-plasty angle. Increaseof obliquity reduces the angle and decrease of

t~·:· i.·...•...•.....t i

¥1<"

Skew constructionParallel construction

Fig. 2.10 The evolution of the parallel and skew types of thecontinuous multiple Zvplasty from a series of interrupted smallZ plasties.

The multiple Z-plastyIn designing a multiple Z-plasty the line of thecontracture can be viewed as a series of contrac­ted segments, on each of which a small Z-plastyis constructed, creating a line of individual Z­plasties, but in practice it is more usual to con­struct them in the form of a continuous multipleZ-plasty (Fig. 2.10). In this, the Zs, instead ofbeing individual, are designed as a continuousseries with a single line along the length of thecontracture and multiple Z side limbs (Fig. 11.7).In theory such a multiple Z-plasty can beconstructed with the side limbs parallel or skew.The presence of scarring in a particular line mayinfluence the construction and make skew flapspreferable, but the use of parallel limbs allowsthe flaps to transpose uniformly. It also avoidsthe construction of a broad-tipped flap witha narrow base, undesirable from a vascularpoint of view, and unavoidable with the skewconstruction.

Whether a multiple Z-plasty has to be usedlargely depends on the depth of the bowstring. Itis unwise to take the side limbs much beyond thebase of the bowstring, and if the making of alarge Z would encroach on the surrounding flatskin to any extent, especially if the skin tends tobe taut, a multiple Z-plasty (Fig. 2.9) is safer andon the whole just as effective.

1~\~r '-'-

-----..c-

THE Z-PLASTY 29

\ .. ••e~.·''.'.7,."..•.••'.I.;.'.. \.<.~,e~.¥,:\ ~ J!\ -.'i?~i4P ..~~~

5 ~ 6'~

Fig.2.11 The steps in planning a Z-plasty so that the transverse limb of the completed Z-plasty lies in a predetermined line. in thisinstance the line of the nasolabial fold.

Fig.2.12 The use of the method shown in Figure 2.11 in revising a scar crossing the nasolabial fold.A The scar outlined. and the line of election - the nasolabial fold.B The lines of the Z. all equal in length. and with each oblique line ending on the line of election.C The scar excised. and the Z flaps transposed.o The procedure completed with the transverse limb of the Z lyingalong the line of election as planned.

30 FUNDAMENTAL TECHNIQUES OF PLASTIC SURGERY

obliquity increases the angle, to a maximum of60°, at which point the common limb becomesperpendicular to the line of the scar.

As the common limb departs from the perpen­dicular the flap becomes narrower and the bloodsupply to its tip increasingly tenuous. Facial skinwith its excellent blood supply is more tolerantof narrow flaps than skin elsewhere on the bodysurface, but even in the face there is a limit topermissible narrowness. A tip angle of 35° is asnarrow as can be used with safety. Even thencare in suturing near the tip of each flap is neces­sary (Fig. 2.13). Fortunately the angle size can begauged at the planning stage before any incisionis made.

In the long facial scar it may be desirable tobreak the line with more than a single Z-plasty.Scars are not invariably straight and lines of elec­tion usually run in different directions in differ­ent parts of the scar. Each Z-plasty has generallyto be planned strictly on its own, with its indi­vidual and quite distinct obliquity. The effect isto convert the single linear scar into a series ofsmaller scars joined by transverse limbs in linesof election, ideally in actual wrinkle lines. Evenat worst, several small scars tend to be less con­spicuous than a single long scar. It is also foundthat a large Z-plasty does not give as good aresult as the smaller Z-plasty. In planningtherefore, the estimated length of the transverselimb should be kept fairly small (Fig. 2.13).

When a multiple Z-plasty is used to break up afacial scar simultaneous lengthening takes place,and this shows as an overlapping of the flaps asthey pass from one Z to the next. Trimming ofthe overlap is usually required in order to reducethe overall lengthening.

Patient selectionWhether or not to incorporate a Z-plasty in revis­ing a particular facial scar can be an extremelydifficult decision. Revision, with or without a Z­plasty, is generally postponed until the scar haslargely settled, and the improvement in itsappearance is near maximal. Revision, incorpor­ating one or more Z-plasties, involves increasingthe length of the wound significantly, and theearly result all too often appears disappointingboth to surgeon and patient. Only once thereaction has slowly settled, and the scars softenonce again, does the benefit become apparent.

Consideration of how the original scar hasbehaved may be of help in deciding. Any sug­gestion of hypertrophy of the original scarshould be seen as a warning against any revi­sion, let alone one which incorporates a Z-plasty.The patient who already has a marked wrinklepattern tends to be a better than average candi­date, particularly if the scar has become pale andmatches the surrounding skin well. The smooth,uncreased adult skin should be viewed withcaution.

Fig.2.13 Scar excision with three Z-plasty inserts. Each insert has been individually planned to place its transverse limb in the direction ofthe local line of election.

The completely settled scar which has re­mained conspicuous because it continues to beredder than the surrounding skin, as some scarsdo even though they have become quite soft, is abad candidate. The end result is likely merely tobe a longer red scar, for each transverse limbstays as red as the rest of the scar and its line failsto merge into the background despite being in a

Fig. 2.14 The use of Z-plasties in revisinga bridle scar crossingthe submandibular concavity.

THE Z-PLASTY n

line of election. The problem is seen most oftenin the patient with the so-called Celtic skin.

A conservative approach to the use of the Z­plasty in facial scars has much to be said for it,confining its use to the patient in whom revisionwill allow an obvious line of election, such as thenasolabial fold, to be used in breaking the line.

The use of the Z-plasty in the revision of facialscars in children is generally contraindicated.Scars as a whole are not considered to behavewell in children in any case, but an added reasonis the smoothness of their skin, and the absenceof wrinkles in which a scar can be concealed.

Use in bridle scarsWhen a scar crosses a hollow, contractionalong its length tends to give rise to a ridged orbridle scar bridging the hollow. Such a scar hassimilarities to a straightforward contractureand the solution is equally the use of a Z-plasty(Fig. 2.14).

Correction of the bridle element requires anincrease in the length of the scar to allow it to sitinto the hollow which it is bridging, but it is also

Axis to be lengthened Axis to be lengthened

,,/\ -, fv ' : --....,,';;: ·.t.. .--.··.;,.,..

.. , ,,;: ---.,.,,-

Axis to be shortened Axis to be shortened

1 2

Fig. 2.15 The useof the Z·plasty in bridle scars, showing(I) therationale of the use of a single Z-plasty in the scar bridginga deephollow, and (2) a multiple Z-plasty in the scar bridging a shallowhollow.

32 FUNDAMENTAL TECHNIQUES OF PLASTIC SURGERY

necessary to shorten the distance from the skin inthe hollow on one side of the scar as it rises to theline of the scar and drops to the hollow on itsother side. These two axes are at right angles toeach other, and if they are viewed as the axes of aZ-plasty constructed around them, transpositionof the flaps will result in lengthening of the axis

Fig. 2.16 The recurrence of trap-door scarring of the cheekfollowing simple excision and suture of the scar.

along the line of the scar allowing it to sit into thehollow, while shortening of the other axis willpull the line of the scar down into the hollow(Fig. 2.15).

When the scar is short and the hollow is deepthe lengthening of the scar which follows trans­position of the flaps of a single Z-plasty may be

Fig. 2.17 The correction of a trap-door scar of the chinfollowing excision of the scar with the insertion of Z-plasties.

Fig. 2.18 The use of Z·plasties in equalising the lengths of thetwo sides of a wound which were previously unequal.

matched by the reduction in length of the trans­verse axis crossing the line of the scar, and asingle Z-plasty (Fig. 2.15(1)) extending along thegreater part of the length of the scar is then likelyto be effective.

Where the bridle scar is longer and relativelyshallow the amount of shortening of the axiscrossing the line of the scar may be quite smallcompared with the amount of lengtheningrequired to allow the scar to lie in the hollow, butthe shortening may need to be repeated alongthe line of the scar. In such a situation a multipleZ-plasty would be the version to use (Fig.2.15(2». Depending on the site of the bridle scar,the detailed planning of such a multiple Z-plastymay involve the added complication of trying tofit the transverse limbs into a line of election. Aslong as it is remembered that each transverselimb can be positioned independently using the

THE Z·PLASTY 33

method shown in Fig. 2.12, this does not poseinsuperable difficulties.

Use in curving scarsThis problem is seen in its worst form when a trap­door of skin which has been uplifted, usually as aresult of trauma, is sutured back in place.Contraction of the resulting scar tissue causes eleva­tion of the tissue within its concavity Seen later theresult may be assumed, not unreasonably, to be dueto bad suturing, but excision of the scar, trimmingof the flap quite flat, and resuture with the greatestcare only results in recurrence of the original state ofaffairs within a matter of weeks (Fig. 2.16).

The fundamental difficulty in surgical correctionof a trap-door scar is the extent of the invisible sub-

Fig. 2.19 The incorporation of Z-plasties during revision of a scarat the margin of a flap. used in conjunction with thinning of the flap,to give a smooth junction between the flap and its surroundings.

34 FUNDAMENTALTECHNIQUES OF PLASTIC SUl\.GERY

cutaneous scarring which produces contracturebeneath the entire area of trap-deering. Under cer­tain circumstances, the Z-plasty can be used tolengthen the marginal scar and break up the sub­cutaneous scarring to good effect. Here, as in cor­recting the bridle scar, an effort should be made toplace any Z-plasty in a line of election, althoughwith the curving scar the planning of the Z-plastyto give the best result from every point of view canbe an extremely difficult exerciseand one in whichfacility comes only with experience (Fig. 2.17).Even with experience, however, the end resultinvariably falls short of the desired ideal.

On occasionthe problem of the curving scar takesa slightly different form, as when the two sides of a

wound to be sutured are unequal in length, as in theexcision of a 'comma-shaped' scar. The taking ofunequal bites in suturing can partially equate thelengths but this has limited effectiveness. The Z­plasty can then sometimes help further to reducethe discrepancy in lengths (Fig. 2.18).

Use in overriding scarsWhere there is a tendency to overriding ofthe tissue on one side of a scar the junctionbetween the two sides can usually be smoothedby incorporating one or more Z-plasties whenthe scar is being excised (Fig. 2.19), and hereagain the use of lines of election should beremembered.