Experimental arthritis in rabbit knees: a study of relief of pressure on one tibial plateau in immature and mature rabbits.

The Hall model of experimental arthritis of the knee (excision of the lateral femoral condyle) offers a unique way of investigating the earliest changes of degenerative arthritis. Predictable degeneration of the lateral tibial plateau occurs when there is lack of contact with an opposing surface. Previous work by Hall and Thompson has not concentrated upon the early changes in proven mature animals of optimum age for a study of simulated osteoarthritis. In this work using mature rabbits, two important findings are documented. The earliest observed change in the joint, beginning at 7 days is loss of matrix protein-polysaccharides from the lateral plateau, with no evidence of change in the subchondral bone until much later; in this respect mature differ from immature animals. Furthermore, there is strong evidence for late (three to 6 months) protein-polysaccharide synthesis in the previously degeneraing articular cartilage in which the residual cells reconstitute an effective matrix.