PURPOSE: We describe a new technique for the treatment of painful instability of the distal ulna after Darrach procedure using an allograft as a mechanical interposition. The purpose of the study is to evaluate the results of this technique.

Methods: In this study we report on 17 patients who underwent revision of their Darrach procedure using an allograft (human Achilles tendon allograft). The average age of the patients was 47 years (range 39–68) and the average time after the original procedure was 15 months. The indication for the revision surgery in all patients was incapacitating pain over the distal stump of the ulna which increased during pronation or supination and with active grip. Pain was assessed using a VAS (Visual Analog Scale). Grip strength was measured using a dynamometer. All patients had instability of the distal ulna, and crepitus or palpable “clicking” during forearm rotation. Radiographs of all patients demonstrated erosion of the medial cortex of the radius, indicating impingment.

Technique: 2 or 3 suture anchors were placed into the medial cortex of the radius, proximal to the sigmoid notch where the impingment occurred. An adequate amount of the allograft was then sutured into an anchovy. The size of the allograft was determined by pronating and supinating the involved forearm with pressure applied to the ulnar aspect of the ulna to assess crepitus. Sutures were placed through the allograft, creating a pillow-shaped spacer. Two or three drill holes were then placed into the distal ulna for fixation of the allograft to the ulna. With final allograft placement there should be significant padding between the radius and the ulna to prevent any palpable crepitus during forearm rotation under compression.

Results: After an average follow-up time of 34 months all patients were re-evaluated by subjective assessment, range of motion, grip strength, pain relief and radiographs. We report 16 patients with good and excellent results and 1 patient with persistent complaints (our first patient). There were no radiographic changes noted.

Conclusions: The use of an allograft as a mechanical interposition between the radius and the ulna has not been described previously. With this technique there is no need for a metallic prosthesis and as much bulk graft as necessary is obtainable. We believe that this technique is an excellent alternative to metal arthroplasty for reconstruction of difficult cases of failed distal ulna resection.