Idiopathic haemorrhagic rupture of the shoulder in destructive disease of the elderly

SUMMARY The cases of two patients with hydroxyapatite crystal associated destructive disease of the shoulder are described who have developed gross haemorrhagic effusions with spontaneous joint rupture and extensive soft tissue damage. No collagenase activity was found in the synovial fluid. Other possible mechanisms of the destructive process are discussed. Key words: hydroxyapatite, joint rupture, haemorrhage, collagenase. There have been several reports describing a des-tructive arthritis of the elderly affecting the shoulders. 1-7 More recently, reports have documented similar damage to additional joints, most commonly the knees. ' 8 The radiological changes include severe cartilage and bone at-trition with joint instability. A relative lack of regen-erative changes in subchondral and periarticular bone has been noted. Rupture of the rotator cuff is common when the shoulder is involved, and areas of articular or 6periarticular calcification have often been seen.6 The synovial fluid is present in often large volume'1 6with a low number of white blood cells, predominantly mononuclear cells, but frequently contains red blood cells and is often lightly blood stained.1 2 6-8 Collagenase and neutral protease activity has been found to be high in the synovial fluid.8 9 Hydroxyapatite crystals have also been detected in the synovial fluid from some of these joints. 8 9 We describe the cases of two patients with apatite associated destructive arthropathy with shoulder involvement who have developed huge grossly haemorrhagic effusions that have ruptured spon-taneously in the absence of collagenase activity in their synovial fluids