Surgery can prevent extensor tendon rupture in the rheumatoid wrist but it is difficult to identify patients at risk. Extensor digiti minimi (EDM) usually ruptures first, but rupture may pass unnoticed because extensor digitorum communis (EDC) extends all four fingers simultaneously. We assessed the value of screening for EDM rupture by examining for absent independent extension of the little finger in a hospital rheumatoid arthritis population.
The EDM test was performed in 550 previously unoperated wrists. Disease activity, joint damage, wrist swelling, tenderness and crepitus were recorded.
Unsuspected EDM loss was found in nine of the 550 wrists (1.6%); dorsal synovitis was absent or minimal in eight and ulnar tenderness was absent in six. EDM loss was not associated with activity, severity or duration of disease.
The EDM test is simple and cheap. It may identify patients at risk and permit prophylactic surgery before hand function is lost.