Crystal deposition and osteoarthritis.

Calcium-containing crystals are commonly found in osteoarthritic (OA) joints. Although most often found in advanced OA, some calcium pyrophosphate dihydrate and apatite can be present in early stages. These crystals could be factors in pathogenesis of OA and even more likely in the progression of disease. Calcium pyrophosphate dihydrate apatites and other calcium phosphates can be mitogenic, can stimulate the release of metalloproteases, and might have mechanical abrasive effects.