British Journalof Plastic Surgery (1990), 43,24-21 0 1990 The Trustees of British Association of Plastic Surgeons

ooO7-1226/90/0043-0024/$10.00

The reverse dorsal metacarpal flap

Y. MARUYAMA

Department of Plastic and Reconstructive Surgery, Toho University Hospital, Tokyo, Japan

Summary-The dorsal metacarpal vessels contribute to the fascial plexus which supplies the skin of the dorsum of the hand. We have successfully used eight reverse dorsal metacarpal flaps based on the dorsal metacarpal arteries. The design and use of the reverse dorsal metacarpal flap is described; it appears to have a reliable vascular basis and its usefulness in covering small soft tissue defects in the-hand is illustrated.

Soft tissue reconstruction of the hand remains a challenge for the plastic and reconstructive surgeon, who must choose whether to use a local flap, a distant flap or a free flap. Local flaps, derived from tissue immediately adjacent to the primary defect, are the first choice but there is a shortage of skin in the hand and there are regions of the hand that should not be used as donor sites since cover of the resultant secondary defect with a skin graft would be inappropriate. These areas are the first web space and all of the palmar skin (Lister, 1981).

The dorsal metacarpal arteries run along the dorsum of the hand and each generally gives off four or five extremely small cutaneous twigs which form longitudinal rows overlying the interosseous spaces, but any one such row may be completely absent (Cormack and Lamberty, 1986).

The anatomical details of the dorsal metacarpal vessels have also been described in detail by Earley and Milner (1987). They stressed the constancy of the first and second dorsal metacarpal vessels and showed the usefulness of second dorsal metacarpal flaps.

We thought that it should be possible to carry skin from the dorsum of the hand as a distally based flap, based on the dorsal metacarpal vessels dis- sected in the same way as the ulnar and radial arteries in reverse forearm flaps.

Operative technique

The skin island is designed over the intermetacarpal space (Fig. 1). The incision is started parallel to the long axis and carried down through subcutaneous fat and the fascia over the dorsal interosseous muscles. The dorsal metacarpal vessels, one artery with two venae comitantes, can be found lying on

the muscles and are included in the flap (Fig. 2A). In the 2nd space, the extensor tendon crosses obliquely over the vessels and should be retracted radially (Figs 1 and 2B). The vessels are divided proximally and the proximal end of the flap is turned upwards. The vascular pedicle can then be seen just under the flap. Dissection of the flap and its pedicle is continued distally to the web space, care being taken not to damage the interconnection between the dorsal metacarpal vessels and those of the palmar and digital vascular system (Figs 3B and 4B). The flap is transposed to the defect and the donor site closed primarily in most instances.

Clinical cases

Our experience with eight flaps has been quite encouraging (Table 1; Figs 3,4 and 5). Except for

Fig. 1

Figure l-Design of the reverse dorsal metacarpal flap

24

THE REVERSE DORSAL METACARPAL FLAP 25

II DMCA II DMCA 1

extensor extensor

A II dorsal interusseus m. 6 II dorsal interosseus m

Fig. 2

Figure 2--(A) Cross-section at distal part of flap. (B) Cross-section at proximal part of flap

one case, the donor sites were closed primarily. One case with a 5th reverse dorsal metacarpal flap showed distal partial necrosis of the flap.

This flap can be used in cases where the skin over the pedicle has suffered a full thickness bum since the vessels reside within the intermuscular septum and are thus far deeoer than the cutaneous vessels (Fig. 5).

Discussion

There is agreement in the literature that the longitudinal dorsal digital arteries in the fingers described by some anatomists (Gray’s Anatomy, 1973) do not exist and that the main trunk of the dorsal metacarpal artery terminates at the level of the metacarpopharyngeal joint (Levame et al., 1967; Iselin, 1973; and others).

Distally the dorsal metacarpal artery ramifies at the level of the metacarpal heads and its branches can be identified distal to the metacarpophalangeal joint travelling to the dorsal proximal phalangeal skin of the fingers where they anatomose with the dorsal branches of the palmar digital arteries. The 4th and 5th metacarpal arteries may be absent in

Table 1

17-30x of dissections (Coleman and Anson, 1961) so, to predict the presence of these arteries, preoperative angiography or Doppler study is advisable.

Earley and Milner (1987) reported the use of skin island flaps from the dorsum of the finger and web spaces nourished by the 1st and 2nd dorsal metacarpal vessels. Making use of the same principle as applied to the distally based forearm flap (Biemer and Stock, 1983) and other distally based flaps (Donski and Fogdestam, 1983; Costa and Soutar, 1988), we have based our flap on the distal end of the dorsal metacarpal vessels, assuming that the metacarpal artery terminates at the distal metacarpal area and that there is good enough connection between its terminal branches and those of the palmar and digital arterial system to sustain a distally based flap, and that there are numerous interconnections in the deep layer of the dorsum of the hand which make the flap safe. Rapid return of circulation following release of the tourniquet has confirmed that the flaps are arterialised.

We report here eight reverse-type dorsal meta- carpal flaps based on the dorsal metacarpal arteries, and this flap appears to be a reliable way to cover small soft tissue defects in the hand.

Case Age Sex Aetiology

1 16 2 2 3 18 4 8 5 I 6 12 I 39 8 40

M M F M F M F M

Bum (ulceration) Bum (contracture) Syndactyly Trauma (acute) Trauma (subacute) Tumour Heat press (contracture) Trauma (subacute)

Dorsal metacarpal artery Results

II II II I II III II-IV V

Good Good Good Good Good Good Good Distal partial necrosis

26 BRITISH JOURNAL OF PLASTIC SURGERY

Fig. 3

Fig. 4

Figure SCase 1. (A) Preoperative view; defect over index finger metacarpophalangeal joint and design of the flap. (B) Operative view; note extensor tendon. (C) Late results. Figure 4-Case 3. (A) Preoperative view; defect of web space and design of flap. (B) Flap raised; it was introduced to the defect beneath the extensor. (C) Late result; the web defect was covered nicely by the flap.

THE REVERSE DORSAL METACARPAL FLAP 27

Figure SCase 7. (A) Preoperative view; heat press injury with contracture of the dorsal MP joint area of the hand. (B) 2nd to 4th vessels included in the flap; the islanded flap was advanced distally. (C) Final result.

References

Biemer, E. and Stock, W. (1983). Total thumb reconstruction: a one stage reconstruction using an osteocutaneous forearm flap. British Journal of Plastic Sirgery, 36,52.

Coleman. S. S. and Anson. B. J. (1961). Arterial oattems in the hand based upon a studiof 650 specimens, Sur&ry, Gynecology and Obstetrics, 113,409.

Cormack, G. C. and Lamberty, B. G. H. (1986). The Arterial Anatomy of Skin Flaps. Edinburgh: Churchill Livingstone.

Costa, H. and Soutar, D. S. (1988). Distally based island posterior interosseous flap. British Journal of Plastic Surgery, 4i, 221.

Domki. P. K. and Fondestnm. I. (1983). Distallv based fasciocu- tanedus flap from-the s&al region. A preliminary report. Scandinavian Journal of Plastic and Reconstructive Surgery, II, 191.

Earley, M. J. and Miher, R. H. (1987). Dorsal metacarpal flaps. British Journalof Plastic Surgery, 40, 333.

Gray’sAnatomy(l973). 35th Edition. Warwick, R. and Williams, P. L. (Eds). Edinburgh: Churchill Livingstone, Fig. 699.

Iselin, F. (1973). The flag flap. Plastic and Reconstructive Surgery, 52, 374.

Levame, J. H., Otero, C. and Berdugo, G. (1967). Vascularization arterielle des teguments de la face dorsale de la main at des doigts. Annales de Chirurgie Plastique, 12,316.

Liater, G. (1981). The theory of the transposition flap and its practical application in the hand. Clinics in Plastic Surgery, 8, 115.

The Author

Yu Maruyama, MD, Associated Professor and Head, Depart- ment of Plastic and Reconstructive Surgery, Toho University Hospital, 6-l 1-I Ohmorinishi, Ohta-ku, Tokyo 143, Japan.

Requests for reprints to the author

Paper received 12 December 1988. Accepted 29 May 1989 after revision.