Amyloid in osteoarthritic hip joints: deposits in relation to chondromatosis, pyrophosphate, and inflammatory cell infiltrate in the synovial membrane and fibrous capsule.

The relationship between osteoarthritic change and amyloid degeneration was studied in 116 joint capsules from osteoarthritic hip joints. Twenty-seven (23%) contained amyloid deposits. Twenty-eight joint capsules showed chondroid metaplasia in the fibrous part. Significantly more amyloid degeneration was found among these. Six joint capsules contained pyrophosphate crystals. Five of these were positive for amyloid. Chronic inflammation of the joint capsule was found in 80% of the cases and was negatively correlated with amyloid degeneration, which is in good agreement with the biphasic theory for the pathogenesis of amyloid. Further investigation is necessary to decide how chondroid metaplasia takes part in the production of amyloid.