[Adaptive patterns of the rheumatoid wrist after radiolunate arthrodesis].

Objective: The aim of this study was the analysis of long-term carpal changes after radiolunate arthrodesis.

Methods: Pre- and postoperative X-rays of 91 wrists in 78 patients with rheumatoid arthritis, who were treated for carpal instability with a radiolunate arthrodesis, were examined concerning the midcarpal joint and the Larsen grade. The mean follow-up was 60 months.

Results: After radiolunate arthrodesis the midcarpal joint space remained unchanged in 28%. In 35% secondary arthritis and in 37% further arthritic destruction occurred. The mean Larsen grade increased from 3.2 to 3.8. Six wrists needed complete arthrodesis 25 to 87 months after the primary procedure and one was treated by total wrist replacement. Adaptive changes of the carpus during progressive disease and in secondary arthritis were recognized. Three types of joint lines could be identified: in 35% of the wrists a "perilunar", in 22% a "radio-midcarpal" and in 3% a purely "midcarpal" joint line. In 40% no specific joint line could be identified.

Conclusion: After radiolunate arthrodesis the carpus remains unchanged in the long run in nearly a third of cases. But even if secondary arthritis or further arthritic destruction occurs as in the remaining cases, the carpus shows an amazing capacity for adaptation. A new intracarpal joint line may develop or the midcarpal joint re-establishes itself.