A CONSECUTIVE SERIES OF 25 THREE-BONE FUSIONS AT MEAN FIVE-YEAR AND MINIMUM TWO-YEAR FOLLOW-UP

Abstract

Purpose of the study: Three-bone arthrodesis, described in 1997, is designed for radiocarpal osteoarthritis with mediocarpal extension. The procedure consists in a capitolunohamate fusion after resection of the scaphoid and the triquetrum. It is associated with carpal shortening proportional to the degree of preoperative wrist stiffness. The objective is to achieve less stiffness than with four-bone fusion.

Material and methods: To verify our hypothesis, the first 24 patients (25 wrists) were reviewed with mean 5.2 years (2–8.5 years) follow-up. All wrists were painful and stiff, and presented radiocarpal and mediocarpal osteoarthritis. There were twelve SLAC III, nine SNAC III and four SCAC III. Mean age was 59 years (range 37–79 years). Mean preoperative range of motion was 50.5° flexion-extension (range 10–105°), mean force was 17 kg (range 10–35 kg). Radiological assessment was performed preoperatively and at last follow-up to determine the Youm index (carpal height) and the Bouman index (carpal translation) and to study the radiolunate joint space.

Results: At last follow-up, all patients had improved but one. Ten wrists were pain free twelve caused some pain at forced wrist movements, and two caused pain daily but at a level below the preoperative level. One patient still suffered from severe pain and required revision for total radiocarpal arthrodesis. The final mean flexion-extension range of motion was 67.8°, for a 13.3° gain in extension and a 3.8° gain in flexion. Ulnar inclination was improved 14° on average. Mean force was 24 kg (73% of healthy side), for a 40% improvement over the pre-operative force. RAdiographically, there was one case of capitolunate nonunion. The radiolunate space remained unchanged. Carpal height decreased 15% on average and the Bouman index increased from 0.90 to 0.93 with no significant ulnar misalignment on the carpus.

Discussion: For pain and force, these results are similar to those achieved with four-bone fusion. The overall results for range of motion are however better for flexion-extension and unlar inclination. In our practice, we have decided to replace the four-bone technique by three-bone fusion because the outcome is a less stiff wrist with a simpler surgical technique. Better results are obtained for stiffer wrists which achieve a significant improvement in motion due to carpal shortening.