Pyrocarbon interposition arthroplasty for proximal capitate avascular necrosis.

Introduction: Avascular necrosis of the capitate head is a rare condition commonly treated with partial wrist fusion. Although good functional results are usually reported, a degree of stiffness is to be expected. We report a pyrocarbon interposition arthroplasty technique in a young sportsman with 3.5 years of follow-up.

Methods: A 15-year-old rugby player presented with a 6-month history of wrist pain and stiffness with no preceding injury. The necrotic bone was replaced with interposition of a pyrocarbon interposition implant (PI(2)) (Tournier, Grenoble, France), originally designed to replace the trapezium. A concave socket was created in the distal fragment to accommodate the implant and prevent dislocation. Regular follow-up included subjective and objective measures.

Results: He was pain free by 6 weeks and regained good functional range of motion and grip strength by 3 months. He returned to playing rugby at the 1-year follow-up. At 2 years, he remained asymptomatic. After 3.5 years, he had no limitations in his heavy manual work as a plant mechanic and retained a good functional range of motion including the dart-thrower's motion.

Conclusions: Medium-term results appear to offer the benefits of being able to return to heavy manual labour as well as retaining a functional range of motion. It is difficult to predict long-term survival, but the outcome so far is encouraging, and conversion to midcarpal fusion remains a salvage option.