Articular cartilage nutrition is mediated by subchondral bone: a long-term autograft study in baboons

Objective: To determine the relative importance of subchondral nutrition in cartilage in autologous transplants and its relation to the development of osteoarthritis (OA). Method: The study was performed in non-human primates with two types of autografts placed orthotopically. One type of autograft was placed into vascularized, Viable cancellous bone well, and another in an identical bone well, but coated with methylmethacrylate. The latter prevented direct contact between the autograft and the host bone. Observations were continued for 3 years. Results: Abrogation of the contact between subchondral bone and articular cartilage-bone autograft had little effect on the cartilage during the first 5-12 months. By 3 years, autografts in the methylmethacrylate wells had non-Vascularized and non-viable subchondral bone. The cartilage in these wells underwent degenerative changes compatible with OA. Conclusion: Interruption of contact between articular cartilage and vascularized subchondral bone resulted in degeneration of the cartilage. The onset and detection of these degenerative changes required long time periods (3 years). Had the experiments been terminated at 1 year or sooner the above described changes would not be apparent. (C) 2000 OsteoArthritis Research Society International.