The distal radioulnar joint in rheumatoid arthritis.

Rheumatoid arthritis (RA) involves the wrist in up to 80% of cases; up to 95% of patients have signs of wrist arthritis after 12 years of disease. The distal radioulnar joint (DRUJ) is involved in 31% to 75% of these patients and is often the first compartment of the wrist involved. The inflammatory sequence of events leads to the "caput ulnae syndrome" described by Backdahl in 1963. Extensor tendon ruptures are frequently associated. The presence of the "scallop" sign on radiographs is an alerting sign for tendon attrition. The gold standard in treatment remains resection of the distal ulnar head, known as Darrach's procedure. The most frequent complication is instability of the proximal ulnar stump. In order to restore stability or to prevent instability, several stabilisation techniques have been reported with free tendon grafts, the extensor carpi ulnaris, the flexor carpi ulnaris, the joint capsule and the pronator quadratus muscle. There is no evidence that stabilisation of the proximal ulnar stump during the initial operation gives better results. Another drawback of ulnar head resection is the progression of ulnar translation of the carpus. There are however several surveys showing that this ulnar translocation is the consequence of the disease rather than the result of the Darrach procedure. Several features such as an increased radial slope (> 23 degrees) and/or destruction of the ulnar corner of the distal radial epiphysis have been mentioned as predictive elements for further ulnar slide of the carpus. The Sauvé Kapandji procedure is in these cases a useful alternative choice. Another advantage of this technique is that it provides a larger surface so that other (radial) procedures can be more easily combined (Chamay partial radiocarpal fusion, wrist prosthesis).