Clinical features of pseudogout attack. A survey of 50 cases.

Fifty patients (15 men and 35 women; average age, 70.8 years) with pseudogout were studied. Arthroscopic biopsy was useful for diagnosis in one case with no light microscopic evidence of crystals in the synovial fluid. Attacks affected 93 sites in 50 patients. Attacks in ten patients occurred after mild trauma, long distance walks, total knee arthroplasty, or intraarticular injection of microcrystalline glucocorticoid. Twenty-five patients had fevers averaging 38 degrees. In five patients the fever was associated with mental confusion. Fourteen patients were initially suspected or misdiagnosed as having septic arthritis. Six patients were treated surgically under this misdiagnosis, with synovectomy complicated by limitation of motion of both knees in one patient. The involvement of more than one joint was noted in 21 patients. Polyarthritis could be an important clue to the diagnosis performed early; the combination of arthrocentesis and injection of microcrystalline glucocorticoid provided excellent therapy.