Volar dislocation of the lunate causing multiple flexor tendon ruptures. An unusual manifestation of pyrophosphate arthropathy

Closed flexor tendon ruptures

We review different causes, diagnoses, and treatment options of closed flexor tendon disruptions in the hand. A classification of closed tendon ruptures based on their mechanism includes traumatic tendon avulsion, spontaneous midsubstance rupture, attrition rupture, infiltrative tenosynovial rupture, and iatrogenic. Certain conditions result in tendon disruption inflicted by more than 1 of these etiologies. In rheumatoid arthritis, tendon rupture may result from attrition on an exposed rough surface, proliferative tenosynovial tendon infiltration, or steroid use.

Attritional rupture of flexor tendons by the head of the ulna associated with a chronic longitudinal radioulnar dissociation

A 62-year-old woman sustained multiple attritional ruptures of the flexor tendons at the wrist caused by displacement of the head of the ulna. She had had injuries of the wrist and elbow when she was young, which were thought to have caused chronic longitudinal radioulnar dissociation with palmar dislocation of the head of the ulna. Attrition of the flexor tendons by the dislocated ulnar head during pronation and supination was the major mechanism for the ruptures in this case. She was successfully treated with tendon transfer and resection of the ulnar head.

Complete palmar dislocation of the lunate in rheumatoid arthritis. Avascularity without avascular changes

We report a case of complete palmar dislocation of the lunate in a rheumatoid patient. X-rays showed a normal bone structure of the lunate without sclerosis or collapse and on MRI an almost normal signal intensity was found. The lunate was removed. Histological examination showed complete necrosis of both marrow and bone cells, and tetracycline labelling showed no fluorescence. This case illustrates that neither X-ray nor magnetic resonance imaging (MRI) can detect complete bone necrosis. When X-ray or MRI changes do occur, these are indications of cellular events following some degree of spontaneous revascularization.