The effect of continuous mild compression of the articular cartilage of rabbit knee joints was studied grossly, histologically, and chemically. Typical gross and microscopic lesions were produced over a six-week period and graded according to accepted techniques. Chemical analysis of the cartilage content of hydroxyproline and hexosamine revealed a greater initial loss of hydroxyproline but both moieties seemed to have been lost after six weeks of compression.
The mechanism for cartilage degradation in this system would appear to be different from that in infection, since it has been suggested that, in infection, the loss of hexosamine is the first event. Possible explanations of these findings are: (1) appearance of some other cellular or matrical substances and the operation of separate enzyme systems degrading chondroitin sulphate and hydroxyproline independently or (2) synthesis of hydroxyproline deficient collagen.