Does osteoarthrosis depend on growth of the mineralized layer of cartilage?

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Hulth-A. Orthopaedic Department, General Hospital, Malmo, Sweden. Clin-Orthop. 1993 Feb. (287). P 19-24. Osteoarthrosis (OA) cannot be adequately studied in exclusively biologic-biochemical terms or exclusively mechanical terms. A common but unproven theory states that OA is primarily a degenerative disease of the cartilage with secondary bone changes. However, there are reasons to believe that primary OA is actually a disorder of the entire joint end, consisting of a reactivation of growth factors in the mineralized part of the joint cartilage (remnants of the growth cartilage of the joint head in childhood). Some growth occurs normally in loaded joints in elderly people. When the joint head expands, the cartilage is mechanically injured by stiffness gradients or impaired nutrition. Attempts to heal the wounds and phagocytosis of detritus release cytokines, enzymes, and additional growth factors within the joint cavity. The released factors in the joint, together with the continuous loading, produce all the typical osteoarthritic changes in cartilage, subchondral bone, and the joint capsule, with stasis and increased bone marrow pressure.