"Milwaukee shoulder"--association of microspheroids containing hydroxyapatite crystals, active collagenase, and neutral protease with rotator cuff defects. I. Clinical aspects.

Four women, aged 63 to 90 years old, presented with mildly painful shoulders of decreased mobility or stability. Radiographic evidence of a complete tear of the fibrous rotator cuff was present in 7 of 8 shoulder joints. Microspheroids containing hydroxyapatite crystals were seen by scanning electronmicroscopy in 12 of 13 synovial fluid samples. All synovial fluids showed activated collagenase and neutral protease activity. This constellation of findings represents a heretofore undescribed syndrome which we have designated "Milwaukee shoulder."