Concurrence of rheumatoid arthritis and calcium pyrophosphate deposition disease: A case collection and review of the literature.

Objective: Calcium pyrophosphate deposition disease (CPDD) is arthritis caused by calcium pyrophosphate (CPP) crystal deposition in joints. It is commonly associated with aging as well as a handful of metabolic syndromes. Recent epidemiologic studies suggest a positive association of CPDD and rheumatoid arthritis (RA).

Feasibility of a tetracycline-binding method for detecting synovial fluid basic calcium phosphate crystals.

Objective: Basic calcium phosphate (BCP) crystals are common components of osteoarthritis (OA) synovial fluid. Progress in understanding the role of these bioactive particles in clinical OA has been hampered by difficulties in their identification. Tetracyclines stain calcium phosphate mineral in bone.