Factors controlling growth and differentiation in the repair of articular cartilage

Two avenues of repair of joint cartilage are permissible biologically: 1) replication of chondrocytes, and 2) callus-like metaplasia of articular mesenchyme. The bulk of cartilage present in advanced osteoarthritis (OA) is formed by the latter means. The osteophytes, eburnation, and myxoid proliferation in the pseudocysts of OA should be regarded as reparative phenomena. OA represents more an aberration than an inability of the joint surface to repair.