Significance of crystals in patients with osteoarthritis of the knee joint


To identify the relation between the presence of calcium pyrophosphate dihydrate crystals (CPPD) and clinical, laboratory, and radiographic findings in patients with osteoarthritis of the knee joint, an analytical study was done in 2001, which included 100 patients with osteoarthritis of the knee joint. Synovial fluid analysis with the examination of a wet preparation under polarized microscopy was conducted for each patient. The study included a comparison between CPPD positive patients and those who are negative for these crystals. CPPD crystals were identified in 48% of the patients. The study shows a significant association of CPPD crystals with genu-valgum deformity, limited flexion and extension, elevated erythrocyte sedimentation rate (ESR) and cloudy inflammatory synovial fluid with poor viscosity. We concluded that CPPD deposition is associated with more disabling and deforming arthritis of the knee joint. Clinical criteria are needed to identify patients with occult CPPD deposition disease.