Abstract
Dear Sir,
The palmar advancement flap first described by Moberg (1964), is used routinely to restore soft tissue coverage with sensibility to the amputated thumb. We present a modification of this flap which has not been previously reported.
A 51 year-old man presented with a partial amputation of the palmar surface of the right thumb in a power saw accident. Examination revealed a 1.5 cm pulp defect proximal to a viable ulnar based flap (Fig 1). Under general anaesthesia, the wound was debrided and reconstructed with a V–Y modification of the Moberg flap (Elliot and Wilson, 1993), preserving the distal skin flap. The lateral incisions of the ‘‘V’’ were carried onto the thenar eminence as originally described, but with two small triangular flaps raised bilaterally on the thenar eminence such that these would lie at the basal crease of the thumb after advancement of the main flap (Fig 2). The flap was raised and advanced on both neurovascular bundles and skin excised laterally at the thumb base to accommodate the small lateral flaps. Tension-free closure was achieved and the patient was managed with a splint postoperatively to limit thumb extension and reduce tension on the flap. After one week, mobilisation of the thumb was encouraged. No early flap complications were encountered and the wounds were fully healed at one month. The patient returned to work as a carpenter at 3 months having recovered partial sensation to the thumb pulp (Fig 3).
Pulp defects of intermediate size are best covered with homodigital neurovascular advancement flaps. The Moberg flap offers the advantages of preservation of length, restoration of sensation and provision of stable soft tissue coverage for defects ≤1.5 cm. Various modifications of this flap have been reported. O’Brien (1968) proposed advancement of an island flap with skin grafting of the secondary defect at the base of the thumb. Elliot and Wilson (1993) described dissection of the whole palmar surface of the thumb with a large ‘V’ from the thenar eminence to avoid the use of a skin graft and allow advancement with less risk of tension, with the proximal defect being closed as a V–Y. With this modification, reduction in the full extension of the thumb can occur if the lateral incisions are palmar to the mid-lateral lines of the thumb. This case report introduces a modification to Elliot and Wilson’s technique in which small lateral triangular flaps are placed at the level of the basal crease of the thumb, with the aim of reducing any subsequent likelihood of linear scar contracture.