Osteoarthritis of the knee in the rabbit produced by immobilization. Attempts to achieve a reproducible model for studies on pathogenesis and therapy.

In order to obtain a reproducible experimental model of osteoarthritis a method of immobilizing the rabbit's knee in extension by means of plastic splint was developed. The right knees of the rabbits were immobilized for periods varying from 4 days to 24 weeks. With the left knees as controls the knees were studied in a variety of ways among these being radiography (126 rabbits), histological sections stained with Alcian Blue (88 rabbits), analysis of 35S-sulphate uptake (22 rabbits) and 35S-autoradiography (6 rabbits). In 27 rabbits the regaining of mobility after immobilization was studied. After 5-6 weeks of immobilization most of the knees showed moderate or severe changes including loss of articular cartlilage and osteophyte formation. Immobilization of the rabbit's knee by this method provokes a fairly easily reproducible type of degenerative joint disease showing similarities to advanced osteoarthritis as seen in humans.