Clinical experience with the second metatarsal artery neurovascular flap

British JoumalofPlastic Surgery (1992),45,136-140 0 1992 The Trustees of British Associationof Plastic Surgeons

BRITISH

JOURNAL

OF

PLASTIC

SURGERY

Clinical experience with the second metatarsal artery neurovascular flap P. A. Eadie, D. A. Jenner and K. Sakai Department of Plastic and Reconstructive Surgery and Microsurgery Research Centre, St. Vincents Hospital, Melbourne, Australia SUMMARY. Three cases of innervated web space flaps from the foot based on the second metatarsal artery and the second common digital nerve are described. This flap provides glabrous skin for digital reconstruction with good sensory recovery and minimal donor site morbidity.

The specialised function of the skin of the hand requires that its replacement following loss should approximate as nearly as possible the normal quality of that skin with its specialised nerve endings. Suitable donor sites for pedicled and free transfer from other fingers, the great toe and the medial aspect of the second toe have been previously described and have been acknowledged as useful reconstructive techniques. The first web space has proved to be suitable but problems with the donor site such as hypertrophic scarring and repeated ulceration have been observed, particularly if thong sandals are worn. In order to decrease donor site morbidity, hemipulp flaps from the second toe or second web space flaps were used for thumb and web space coverage. The principal blood supply of this flap is derived from the plantar vascular system. The posterior tibia1 artery divides just proximal to the abductor hallucis into the medial and lateral plantar arteries. The lateral plantar artery is generally the larger of the two, and with the perforating branch from the dorsalis pedis artery forms the plantar arch. The second metatarsal

plantar artery courses towards the second web space, receives a contribution from the dorsal system via the dorsal communicating branch over the transverse metatarsal ligament and then divides to supply the contiguous sides of the second and third toes (Fig. 1). Neurovascular flaps based on this digital artery have not been previously described.

Case reports Since 1987, the second toe hemipulp or web space flap has been used in three patients for reconstruction of their first web space or thumb pulp. All patients have been carefully followed and a formal assessment performed after a minimum follow-up period of 9 months. At follow-up, appearance and function were assessed. Sensory examination was performed by measuring moving and static two-point discrimination, using Semmes-Weinstein monofilaments, recording temperature and light touch perception, stereognosis and sweating. The unoperated second toe

Fig. 1

Figure: l-The anatomy of the second metatarsal flap illustrating the neurovascular supply from the second metatal sal artery and the comm on digital nerve.

136

Clinical Experience with the Second Metatarsal Artery Neurovascular

was assessed in the same manner. Donor site morbidity was evaluated for scar quality, cold intolerance and gait. Case 1 An l&year-old schoolboy crushed his non-dominant left hand in rollers with extensive degloving and amputation of his fingers through the PIP joints. Skin coverage was initially obtained with a combination of a pedicled groin flap and split thickness skin grafts (Fig. 2). Because of a persistent first web space contracture and the insensitivity of the thumb pulp, a free neurovascular flap from his second foot’s web space was transferred and inset across the first web space and along the contiguous sides of his thumb and remainder of his index finger. The flap measured 7 x 3 cm and was based on the second plantar metatarsal artery, a dorsal vein and the common digital nerve to the second web space. The artery was anastomosed to a branch of the ulnar artery via a vein graft. The nerve was split into two and anastomosed to two digital nerves in the palm. The donor site was closed

Flap

137

with a Wolfe graft from his groin. He had no postoperative problems and assessment was carried out 27 months after surgery (Table 1). He currently works as a clerk and uses his left hand for such activities as driving.. He can pick up objects between his thumb and the proximal phalanx of his index finger, the area where the flap has been placed (Fig. 3). He has a thumb-index span of 6 cm. His donor site is shown in Figure 4. Case 2 A 28-year-old man was admitted following a total avulsion of his left thumb pulp from proximal to his interphalangeal joint. His flexor tendon was exposed and he had a comminuted fracture of the distal phalanx. The fracture was reduced and internally fixed with a Kirschner wire. A neurovascular pulp flap from his right second toe was transferred based on the lateral digital plantar artery and nerve, and a dorsal vein. Arterial anastomosis was performed in an end-to-end fashion via a vein graft to the radial artery in the snuff box. The flap digital nerve was anastomosed to

Fig. 3

Fig. 2

Fig. 4 1, 18 months after original injury illustrating groin flap of degloved hand. Figure S-Case 1, post transfer of second web space flap to first web space on the hand, showing pinching capability between thumb and index proximal phalanx. Figure &Donor site of Case 1.

Figure 2-Case

British Journal of Plastic Sureerv

138 Table 1

Results of appearance and sensory assessment at follow-up Case 1

SZPD MZPD s-w Temp. Donor morbidity Stereognosis Cold intolerance Follow-up (months)

Case 3

Case 2

Web

Foot

Thumb

Foot

Thumb

Foot

11 12 Purple Normal None Normal None 27

9 11 Purple Normal

10 10 Purple Normal None Normal None 11

13 10 Blue Normal

15 12 Purple Normal None Normal None 9

10 10 Green Normal

None

None

None

S-W = Semmes-Weinstein

the ulnar digital nerve of the thumb. The donor site of the foot was closed with a Wolfe graft. He returned to his former occupation as a mechanic 5 months following injury and assessment was carried out 11 months post surgery (Table 1). His only functional problem is in picking up very fine objects. Figures 5 and 6 illustrate his thumb postoperatively and Figure 7 his donor site. Case 3 A 28-year-old man was admitted following an avulsion of most of the pulp of his right thumb, associated with a

fractureofthe headofhisproximalphalanx. Initialtreatment consisted of reduction and fixation of the fracture with Kirschner wires and coverage of the wound with a pedicled groin flap (Fig. 8). Four months later his groin flap was removed and a free hemipulp flap from the lateral aspect of his left second toe, based on the second plantar metatarsal artery, one dorsal vein and the second common digital nerve was transferred to the distal phalanx of his thumb. An endto-end anastomosis was performed between the thumb and radial digital artery and the flap artery via a vein graft. The flap nerve was anastomosed to the ulnar digital nerve. The

Fig. 5

Fig. 6 Figures 5, &Case

2, post transfer of second toe hemipulp

flap to thumb.

Fipre ‘I-Donor

site of Case 2.

139

Clinical Experience with the Second Metatarsal Artery Neurovascular Flap donor site was closed with a Wolfe graft from his groin. His postoperative course was uneventful and he returned to work 1 month after surgery. At assessment 9 months post surgery his only functional deficit involves picking up fine objects (Table 1). His postoperative appearance is illustrated in Figure 9 and his donor site is shown in Figure 10.

perception and all flaps regained the function of sweating. None of the patients complained of any disability from the donor site and its appearance was deemed satisfactory by them. Cold intolerance was neither a problem with regard to the hand or the foot. The results of each case are documented in Table 1.

Results

Discussion

All three patients had satisfactory sensory recovery, with a moving two-point discrimination between 10 and 12 mm. On Semmes-Weinstein assessment all achieved the grade of “diminished protective sensation” (purple filament). In addition, all three patients had normal temperature, light touch and stereognotic

Reconstructive requirements following traumatic loss of the thumb pad include restoration of sensation with durable and well padded skin. Small defects can be managed with skin grafts or volar advancement flaps. Larger areas may require the introduction of vascularised and sensate skin from a distant site. Neurovascu-

Fig. 8

Fig. 10

Fig. 9 Figure &Case 3 illustrating Donor site of Case 3.

coverage

of thumb

tip with groin flap. Figure !9--Case

3, post transfer

of second toe hemipulp

flap. Figure lO-

British Journal of Plastic Surgery

140

lar island flaps from other fingers have been described (Littler, 1953 ; Tubiana and Duparc, 1961; Holevich, 1963) but these have problems of cerebral differentiationof the donor and recipient fingers, plus anaesthesia of the donor finger. Neurovascular free flaps can be considered when local or regional flaps are inappropriate or unavailable. The first web space of the foot has been previously cited to have the unique advantage of a large area with minimal donor site morbidity, and skin identical to the hand (Morrison et al., 1978). The flap can range from a hemi-pulp to the whole of the first web space, depending on the size requirements. Two-point discrimination of the first web space varies between 8 and 15 mm. Strauch reported that an increase in sensibility occurred following transfer, possibly due to an increase in cortical representation or an increased density of peripheral receptors (Strauch and Tsur, 1978). However, other authors have not agreed with this, recording only moderate two point discriminations, with one group of workers recording an actual deterioration in sensibility of the flap (Morrison et al., 1978). The second toe pulp or web space flap based on the medial digital artery has also been used for similar problems (Buncke and Rose, 1979; Logan et al., 1985). It has usually been second choice to the great toe as its two-point discrimination is greater (10-25 mm). Our two patients who had hemipulp flaps transferred to their thumbs both had good sensory recovery in their flap. Case 2 had achieved a moving two-point discrimination of 10 mm and Case 3 had a moving two-point discrimination of 12 mm, 9 months after surgery. Both had returned to their previous occupations and were not experiencing any difficulty in their day-to-day activities. In addition, neither had any functional problems with their donor sites and cosmetically these were very acceptable. The sensory recovery in the first case was similar and the addition of the neurovascularised flap increased his first web span and allowed him to pinch to the proximal phalanx of his index finger. Elevation of this flap can be more difficult than the first web space flap and as the arterial supply comes from the plantar system, a shorter artery is available and a vein graft is required. The diameter of the vessel will also be smaller than that of the first toe. However, neither of these disadvantages are contraindications to the use of this flap. The second web space flap is narrower but almost as long as the first web flap and as such is useful for smaller defects. It is comparable

to the first web space flap in terms of the type of tissue and sensory recovery and is indicated for smaller defects when minimal secondary defect is important. In conclusion, the second web space neurovascular flap has good sensory recovery, with patients achieving a moving two-point discrimination of up to 10 mm. If the size defect is appropriate it is an ideal choice for replacement of glabrous skin. In addition, it has the unique advantage in its own right in having even less donor site morbidity than the great toe. When the flap is based on the lateral vessels there is no interference with the first web space and the patient’s ability to wear thong sandals, a very important facet of Australian life!

References Buncke, H. J. and Rose, E. H. (1979). Free toe to fingertip neurovascular flaps. Plastic and Reconstructive Surgery, 63,607. Hole&h, J. (1963). A new method of restoring sensibility to the thumb. Journalof Bone and Joint Surgery, 45B, 496. Littler, J. W. (1953). The neurovascular pedicle method of digital transposition for reconstruction of the thumb. Plastic ana’ Reconstructive Surgery, 12,303. Logan, A., ERiott, D. and Foueher, G. (1985). Free toe pulp transfer to restore traumatic digital pulp loss. British Journal of Plastic Surgery, 38,497.

Morrison, W. A., O’Brien, B. and Hamilton, R. B. (1978). Neurovascular free foot flaps in reconstruction of the mutilated hand. Clinics in Plastic Surgery, 5,265. Stmwch, B. and Tsur, H. (1978). Restoration of sensation to the hand by a free neurovascular flap from the first web space of the foot. Plastic and Reconstructive Surgery, 62, 361.

Tubiana, R. and Duparc, J. (1961). Restoration of sensibility in the hand by neurovascular skin island transfer. Journal of Bone and Joint Surgery, 43B, 474.

The Authors PatrIcin E&e, FRCSI, Registrar in Plastic Surgery, St James’s Hospital, Dublin, Ireland. Formerly Research Fellow and Clinical Assistant in Plastic Surgery, Microsurgery Research Centre, Melbourne, Australia. David A. Jenner, FRACS, Consultant Plastic Surgeon, St Vincents Hospital, Melbourne, Australia. Kamhiro Sakd, MD, Research Fellow and Clinical Assistant in Plastic Surgery, Microsurgery Research Centre, Melbourne, Australia. Requests for reprints to: Dr Patricia A. Eadie, Department of Plastic Surgery, St James’s Hospital, PO Box 580, Dublin 8, Ireland. Paper received 16 July 1991. Accepted 26 July 1991.