Abstract Five cases of flexor tendon rupture in surgically treated rheumatoid wrists were studied. The tendon ruptures occurred in the thumb and index finger, and the ruptures site was in the carpal tunnel in all five cases. The main cause of rupture was the formation of bony irregularities in the form of bony spurs in the carpal bones, mainly in the scaphoid, or at the volar aspect of the distal radius, as a result of rheumatoid erosion. In all five cases, tendon reconstruction and bony spur excision were conducted, and good recovery of phalangeal function was achieved. To clarify the causes of the rupture of the flexor pollicis longus in rheumatoid hands, we used three-dimensional computed tomography on 19 rheumatoid wrists without tendon rupture to investigate the presence or absence of bony spurs in the volar aspect of the scaphoid. The results showed a correlation between the frequency of scaphoid spurs and progression of bone changes as checked by radiography.
