A GASTROCNEMIUS MUSCULOCUTANEOUS FLAP

By ARTHUR M. MORRIS, F.R.C.S. Plastic Surgery Unit, Dundee Royal In.rmary, Dundee and Bridge of Earn Hospital,

Perth, Scotland

WHILE the cross-leg flap provides good quality skin cover with a very high success rate, the disadvantages of the crossed leg position and the multiple stages have stimulated the search for alternative and preferably single stage operations. Conventional local skin flaps are occasionally possible (Harrison and Saad, 1977) but are restricted in size by the need for a broad base to the flap. Ger (1968, 1971) popularised the concept of filling a leg defect with a transposed local muscle and then split skin grafting the muscle; many variations have since been published (Pers and Medgyesi, 1973; McHugh and Prendiville, 1975). Orticochea (1972) first described the transplantation of the over- lying skin with the muscle and McGraw et al. (1976) and McGraw and Dibbell (1977) have shown that in many instances skin overlying muscles receives its blood supply from perforating branches of the vessels supplying the muscle.

An analysis of the results in 165 cross-leg flaps (Morris and Buchan, 1978) showed that the proximally based flaps had a better survival at the attachment phase, but on division the flaps often became congested and then had a higher incidence of necrosis at that stage than the other flaps. This suggested that the venous drainage with com- petent valves was a very important factor in flap survival. A flap based proximally at the popliteal fossa would have the advantage of a good venous drainage with the valves orientated correctly (Fig. I). A study was therefore carried out to find any pattern of arterial supply to the skin of the calf from arteries in the popliteal fossa.

FIG. I. The venous network shown by tram-illumination in a conventional cross-leg flap of the medial calf draining towards the long saphenous vein.

FIG. 2. The area of skin staining after a methylene blue injection into the artery to the lateral head of the gastrocnemius muscle in the cadaver.

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A GASTROCNEMIUS MUSCULOCUTANEOUS FLAP 217

Cadaver injection studies. Fluorescein and methylene blue were introduced by a fine polythene cannula into the branches of the popliteal artery in 7 legs. Injection of the medial and lateral geniculate arteries gave very variable results and in some cases no skin staining at all. The medial artery usually gave a larger skin supply. Five injections of the artery to the lateral head of gastrocnemius stained an area of skin stretching from I inch (2-5 cm) below the level of the head of the fibula varying from 4 to 8 inches (IO to 20 cm) in length and from 2 to 3 inches (5 to 75 cm) in width on the posterior calf. Five injections in the artery to the medial head of the gastrocnemius gave similar skin staining to an area more medially placed but of comparable size (Fig. 2).

In vivo studies. Two patients who required amputation of a leg were available. The area of skin outlined by injection into the medial gastrocnemius artery in a

34-year-old woman measured 8 by 3 inches (20 x 7.5 cm). The stained skin extended 2 inches (5 cm) beyond the distal end of the medial head of the gastrocnemius, in spite of half the width of the flap having previously been burned and skin grafted. The stained skin was then raised as a flap based on the popliteal fossa and could cover the upper half of the shin and the whole knee joint medially, and anteriorly up to 2 inches (5 cm) above the patella (Fig. 3).

A flap based on the medial head of the gastrocnemius was also raised in a 69-year- old man. This measured 8 by 3 inches (20 x 7.5 cm) and appeared to have an adequate blood supply with no blanching or venous congestion. Its range extended from the upper half of the shin to the knee joint.

Case report. A 79-year-old woman sustained deep burns of the knee following a minor cerebra-vascular accident when she left a hot water bottle against her knee all night. The burn penetrated to the patella and the ligamenturn patellae was completely destroyed. The knee joint and the tibia were also exposed. After surgical debridement a musculo-cutaneous flap based on the medial head of gastrocnemius measuring 7 by 38 inches (IS x 8 cm) was raised and used to cover the exposed bone and joint (Fig. 4). The remainder of the defect and the flap donor site was split skin grafted. The flap and graft healed uneventfully.

218 BRITISH JOURNAL OF PLASTIC SURGERY

FIG. 4. A. Deep burn of the knee. B. Outline of the flap based on the medial head of the gastro- cnemius muscle. C. The flap to cover the knee defect. D. The leg healed at IO days. E. Leg

elevated to show knee extension at 6 months.

Mobilisation was slow because of the patient’s frailty and the cerebra-vascular accident, but after 6 weeks she was able to walk with an extension splint over the knee. It had been intended to perform a knee arthrodesis but, after 12 weeks, active extension of the knee re- appeared spontaneously and she is now fully mobile on the unsupported knee 6 months after operation.

SUMMARY

The results of injection studies in cadavers and in vivo flap construction suggested that a flap based on the medial or lateral gastrocnemius muscle and the skin of the popliteal fossa draining to the long or short saphenous systems respectively provides a good length to breadth ratio flap without prior delay.

Such a flap based on the medial gastrocnemius muscle was used successfully in 1 patient.

A GASTROCNEMIUS MUSCULOCUTANEOUS FLAP 219

REFERENCES

GER, R. (1968). The management of pretibial skin loss. Surgery, 63, 757. GER, R. (1971). The technique of muscle transuosition in the onerative treatment of

trauma& and ulcerative &ions of the leg. J&owal of Trauma, ;I, 502. HARRISON, S. H. and SAAD, M. N. (1977). The sliding transposition flap: its application

to leg defects. British Journal of Plastic Surgery, 30, 54. MCCRAW, J. B., MASSEY, F. M., SHANKLIN, K. D. and HORTON, C. E. (1976). Vaginal

reconstruction with gracilis myocutaneous flaps. Plastic and Reconrtructive Sur~yer\. 58, 176.

MCCRAW, J. B. and DIBBELL, D. G. (1977). Experimental definition of independent myocutaneous vascular territories. Plastic and Reconstructive Surgery, 60, 212.

MCHUGH, M. and PRENDIVILLE, J. B. (1975). Muscle flaps in the repair of skin defects over the exposed tibia. British Jourzal of Plastic Surgery, 28, 205.

MORRIS, A. M. and BUCHAN, A. C. (1978). surgery of the lower leg and foot.

The place of the cross leg flap in reconstructive

Surgery, 31, 138. A review of 165 cases. British Journal of Plastic.

ORTICOCHEA, M. (1972). The musculo-cutaneous flap method: an immediate and heroic substitute for the method of delay. British Journal of Plastic Surgery, 25, 106.

PEAS, M. and MEDGYESI, S. (1973). Pedicle muscle flaps and their applications in the surgery of repair. British Jomxal of Plastic Surgery, 26, 313.