Distal ulna excision (Darrach procedure) is an operation to remove the end of the ulna bone at the wrist. It is performed for painful arthritis or instability of the distal radioulnar joint (DRUJ).
An incision is made on the ulnar side of the wrist. The distal 1–2 cm of the ulna is removed. Soft tissues are repaired to stabilise the remaining ulna stump. The TFCC remnants may be used to create a soft tissue cap. The operation takes 30–45 minutes.
The Darrach procedure is recommended for painful DRUJ arthritis (rheumatoid or post-traumatic), malunited distal radius fractures with DRUJ incongruity, and failed other DRUJ procedures, particularly in lower-demand patients.
Splinting, corticosteroid injection, activity modification. The Sauvé-Kapandji procedure is a surgical alternative that preserves the ulnar head.
X-rays. Standard pre-assessment. Day-case procedure.
Pain relief and improved forearm rotation. Works well in low-demand patients and rheumatoid arthritis.
The remaining ulna stump may be unstable and click or clunk.
Some weakness due to loss of the ulnar buttress.
The remaining ulna may impinge on the radius during rotation.
The carpus may shift ulnarward over time.
Dorsal cutaneous branch of ulnar nerve.
Wound infection.
Local, regional, or general anaesthesia.
Splint for two weeks. Gentle rotation exercises from two weeks. Full activity at six to eight weeks.
Reviews at two weeks and six weeks.
Some grip strength reduction is expected, but most patients find the pain relief outweighs the small strength loss. In lower-demand patients, this is rarely a problem.