By C. P. SAWHNEY, M.S. Associate Professor of Plastic Surgery, Postgraduate Institute of Medical Education and Research, Chandigrah, India

Transcription

1 CONTRACTURE OF SKIN GRAFTS AND ITS RELATION TO CLEAVAGE LINES OF SKIN By C. P. SAWHNEY, M.S. Associate Professor of Plastic Surgery, Postgraduate Institute of Medical Education and Research, Chandigrah, India CONTRACTURE of skin grafts has an important bearing on the ultimate outcome of many plastic surgical procedures ; consequently the study of its various aspects and of the factors modifying it assumes importance. The thickness of the graft and the nature of the bed on which it is applied are known to be important determining factors. It is reasonable to assume that inherent biomechanical properties of the surrounding normal skin which are determined by the arrangement of collagen and elastic tissue in dermis, would also exert some influence on the contracture of skirt grafts. Cox (1941) demonstrated a close correlation between the predominantly parallel arrangement of collagen and elastic tissue fibres in the dermis and the cleavage lines of skin, so that study of the relation of skin graft contraction to lines of cleavage in skin should give indirect evidence of the role played by the structural characteristics of adjoining skin. A detailed study of several facets of contracture of skin grafts including its possible relation to cleavage lines of skin has therefore been undertaken. Material and Method.--The study is based on observations of 5 intermediate thickness split skin grafts placed in various representative regions of the body in young adults under 30 years of age. Only grafts which took IOO per cent. were included. The initial measurements of the grafts were taken at the time of the primary dressing on the sixth or seventh post-operative day. Subsequently, measurements were done at short intervals until the grafts were fully contracted. The period of observation varied in different regions because of the difference in the time taken by the grafts to contract fully. The graft edges were marked with gentian violet and the exact impression of the graft was taken on a piece of damp lint which was subsequently transferred to a tracing paper. The surface area as well as the length of the graft in various directions, i.e., vertical, horizontal and diagonal, was measured with a planimeter. Contracture was determined by the following formula : Contracture per unit area (c) = Percentage contracture Decrease of wound area over a period = c IOO initial wound area Results.--For purposes of convenience, different areas of the body have been grouped according to the apparent laxity of the skin. The skin over the scalp, forehead, arms and legs is tightly draped whereas in the eyelids, neck and dorsum of hands, it is very loose. The chest, abdomen and back constitute areas where the laxity of the skin is midway between these extremes. In the remaining areas, skin laxity varies continuously depending upon postures adopted. These regions include flexor and extensor surfaces of joints. However, taking into consideration the resting postures or postures adopted during work, it is apparent that most skin is lax most of the time. It became obvious during the course of study that contracture of skin grafts is Comparable in regions grouped according to relative skin looseness. 233

2 234 BRITISH JOURNAL OF PLASTIC SURGERY Contracture per unit area varies widely in different regions even with skin grafts of the same thickness ; the extremes measured were 11"5 per cent. on the leg and 80.2 per cent. on the dorsum of the hand. This difference is understandable if laxity of the skin in different areas is also taken into consideration. The rates of contracture are highest in areas of great laxity of skin varying from 52.7 per cent. on the neck to FIG. I 1001 BO. : 80. ~z 70" N ~o ~ 2o ~. I00; i r'" f---~ -~ 2-9o. /r ~ ~o. / " / ~ SCALP o 50 ~/ -~- FORE HEAl) ~ 40 // //... ARM ~ 30 z" ~-0 5 I FIG. 2 I0 0,,Sl -- ABDOMEN // ---RAD~ i'-/... CHEST.5 I PERIOD ~N DAYS FIG. 3 ~OC ~c 7oi ~ 6o. ~ 5o ~, 40 3o ~ 20 ~ D #" ~.T.-" / 7 ~ so,v // ~Do / -- PALM IOO ~ 6o ~_ 4o // --- ANKLE,~ B0 ~ 20 //... INGUINAL REGION IO,T.,/"S f~" 'j" //..." /.. [/" -- DORSUM OF HAND! f"... EYE LID 0 5 I I FIG. 4 FIG. 5 Fig. I.--The extent to which contraction of a split skin graft (expressed as percentage) takes place in various regions of the body. Figs The degree of contraction (expressed as percentage of total contraction) in skin grafts in relation to the period of observation in various regions of the body per cent. on the hand but are lowest in areas where skin is tightly draped, varying from II'5 per cent. over the shin to per cent. on the scalp (Fig. I). The difference is highly significant (P < o-oi). There seems however, to be no significant difference between rates of contracture in eyelids, neck, dorsum of hand and flexor surfaces of joints (P > O-D5). This is explained by the fact that skin is lax most of the time on flexor surfaces of joints due to the postures adopted.

3 CONTRACTURE OF SKIN GRAFTS--RELATION TO CLEAVAGE LINES OF SKIN 235 JfilGS. 6-II Contraeture of skin grafts and its relationship to lines of cleavage in various regions of the body. Continuous line shows the shape and size of a graft after complete take. Dotted line shows the shape and size of a graft after it is fully contracted.,/!iu//ll il/! li' ll'l l I'/ll l illj I'l)llll'] ~//!llq 1/i;,l'!!,\ 1", f,s'is\ \)s il,'sl FI~. 6 fl/ ~IG. "7

4 236 BRITISII JOURNAl. OF PLASTIC SURGERY d,<,,,,,,,,,. t r" ~,Z--x:?;.,.. t~k FIG. 8 X i f \ \ ~ \ ~\ ///~"///.:I \ \ -- / /'/ FIG. 9 \ \ \\ ~l/h/'////'l \\ \ \ \lq I, liliil \\ \\ li, f t Ilf,,t I / FIG. IO

5 CONTRACTURE OF SKIN GRAFTS--RELATION TO CLEAVAGE LINES OF SKIN 237 FIG. I r The time taken for maximum contracture to occur varies from II to 62 days. In areas where the skin was loose and the grafts contracted undisturbed, the progress of contracture was rapid and reached a maximum in 2I days, but in areas where there was recurring stretching especially in the popliteal fossa, the contracture took place over a longer period. Contracture starts immediately after the graft has taken and progresses rapidly during the first two weeks. The rate and duration of contracture in different sites is shown in Figures 2-5. Grafts are fully contracted within two to three weeks in the inguinal region, the eyelids, the dorsum of the hand, the palms, the flexor surface of the fingers and the neck. In other sites however, a slower rate of contracture continues until the grafts are fully contracted, usually in one to one and a half months. It is possible that the contracture process could be more protracted if attempts were made to prevent its full development. The contracture at different sites followed the same pattern irrespective of the state of skin laxity or the degree of ultimate contracture. Cleavage Lines and Contracture.--When skin grafts contract, the skin edges are drawn inwards by forces which act centripetally and significant contracture occurs in all directions. The rates of contracture in different directions vary however and seem to be influenced by the cleavage lines of the skin. Along lines of cleavage they are minimal compared with those obtained in directions perpendicular and diagonal to them (Figs. 6-11). The differences are statistically significant all over the body (P< 0"05). The variations are more marked in the abdomen, chest, back, face and flexor surfaces and less obvious in the scalp, forehead, legs, arms, eyelids, neck and dorsum of the hand. SUMMARY AND CONCLUSIONS I. Fifty split skin grafts placed in different regions of the body have been studied for contracture rates. 2. The rates of contracture of skin grafts vary directly with the skin laxity in the particular region, being minimum from I I to 2 7 per cent. in the scalp, arms and legs ; medium from 41 to 4 8 per cent. in the abdomen, chest and the back, and high from 5 2 to 8o per cent. in the neck, eyelids and the dorsum of the hand. 3. Rapid contracture occurs in the first two to three weeks and the contracture is complete generally in one to one and a half months. 4. Contracture of skin grafts is least along lines of cleavage compared to lines perpendicular and diagonal to it and the difference is highly significant. REFERENCE