This procedure can be performed under regional ankle block anaesthesia, with an ankle tourniquet. A dorsal longitudinal incision is made over the 1st metatarsophalangeal joint just medial to the extensor hallucis longus tendon. The incision starts at the neck of the proximal phalanx and extends ~ 2 cm proximal to the metatarsal head. Skin hooks are used to retract the skin edges, small bleeders are clamped and bovied, and the incision is then carried deep through the capsule down to bone. Subperiosteal dissection is carried out over the proximal phalanx. The joint capsule is reflected, allowing direct visualization
Fig. 8.7 Keller resectional arthroplasty of the 1 st metatarsophalangeal joint, before and after removal of the proximal one-third of the base of the proximal phalanx.
of the metatarsophalangeal joint. The collateral ligaments are cut using a Beaver No. 64 mini-blade or No. 15 blade and the proximal one-quarter to one-third of the proximal phalanx is transected, perpendicular to the long axis of the phalanx, with a power saw (Figs 8.7,8.8). The most difficult part of this procedure is removing the phalangeal base. The bone is grasped with a bone clamp and the intrinsic muscle attachments, for the flexor hallucis brevis and the adductor hallucis, are carefully freed using a Beaver No. 64 mini-blade. Care must be taken to avoid cutting the flexor hallucis longus tendon. The wound is irrigated with normal sterile saline and a piece of Gelfoam® sponge (haemostatic absorbable gelatin) is placed in the void created by removal of the phalangeal base. The joint capsule is closed with 3-0 absorbable sutures in a simple interrupted fashion. If possible, the capsule should be purse stringed, interposing soft tissue between the metatarsal head and the phalangeal base. The skin is closed with a 4-0 absorbable suture in a running subcuticular fashion and Steri-Strips® are placed across the incision.
The use of one or two Kirschner wires to maintain the hallux position is at the surgeon's discretion. I have not found it necessary to use Kirschner wires, and prefer splinting, with early passive range of motion exercises to maintain hallux dorsiflexion.
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