Technique

Classically, radialization begins with an S-shaped incision along the dorsal aspect of the forearm onto the wrist. Initially two important nerve branches are identified dorsally and protected: the dorsal branch of the ulnar nerve and the superficial branch of the median nerve. The radial artery is identified. The extensor retinaculum is identified and divided longitudinally on its radial side giving access to the extensor tendons. The tendons are dissected free of all of their insertions to the carpal and metacarpal bones. All fascia on the radial side of the wrist and the joint capsule are released. All radial wrist flexors and extensors are detached permitting the distal end of the ulna to mobilise. If the ulna is very bowed, an opening wedge osteotomy is done at this stage.

The ulna is translocated under the radial carpal bones and secured with a 1-2 mm K wire. The wire is passed through the second metacarpal, scaphoid and medulla of the ulna. The wrist joint capsule is repaired. The extensor retinaculum is passed under the extensor tendons to limit the tendency to adhesions. The mobilised radial wrist flexor and extensors, often sharing a common muscle belly, are sutured end-to-side onto the tendon of extensor carpi ulnaris (ECU). Often ECU needs to be shortened to accommodate the new relative proximity of the fifth metacarpal.

After haemostasis, the wound is closed. There may be a need to remove excess skin and subcutaneous tissue on the ulnar side of the wrist. A long arm plaster splint is used to maintain the position for 3-4 weeks or longer if an ulnar osteotomy has been required. Night splintage and extension exercises may be necessary to limit the tendency to finger flexion. The K wire is removed at approximately six months from the first procedure; often this is combined with a pollicisation where there is thumb hypoplasia.