Great Western Hospital, Rheumatology, Swindon, Wiltshire and
1 Nuffield Orthopaedic Centre, Hand Surgery, Oxford, UK
SIR, We thank Dr Ehrlich [1] for his comments. Our consistent operative finding that the triangular fibrocartilage was ruptured in wrists with extensor tendon rupture by attrition on the ulnar head lends support to the conclusion that Dr Ehrlich and his colleagues reached in 1959. Whether triangular fibrocartilage rupture is a necessary condition for extensor tendon rupture or simply a surrogate for severe distal radioulnar arthritis is less clear. Although the number of patients with tendon rupture limits the power of our study, rupture did not appear to be associated with ulnar head prominence, ulnar head tenderness or distal radioulnar crepitus. We did not assess distal radioulnar instability, which might be a better marker of triangular fibrocartilage rupture. Contrary to Dr Ehrlich, we found that the extensor digiti minimi was the most common tendon to be ruptured, probably because it lies most directly over the ulnar head. Magnetic resonance imaging is not part of our routine assessment of the rheumatoid distal radioulnar joint, since the complex signal obtained in these damaged joints may make assessment of the triangular fibrocartilage difficult. Moreover, we believe that the resolution is not yet sufficient to detect reliably the dorsal capsular perforation that allows contact between the roughened ulnar head and the extensor tendons. The perforation is shown more reliably by arthrography of the distal radioulnar joint.
Notes
Correspondence to: L. Williamson. E-mail: williamson{at}greenwillow17.fsnet.co.uk
References