A preconditioned arthritic hip model.

The authors describe a reproducible, inexpensive, large animal model of a preconditioned arthritic hip that can be subjected to various types of surgical reconstructions to assess, compare, and improve their efficacy. In 76 sheep the right hip was denuded of articular cartilage and followed clinically, radiologically and histologically for up to 2 years. In 15 sheep the cartilage was removed and the subchondral bone penetrated, and in 61 the cartilage alone was removed. By 3 months all sheep had developed arthritic changes similar to those seen in humans, with osteophytes, cysts, bone erosions, and periarticular inflammation. The sheep in which the cartilage was removed and the subchondral bone penetrated developed a severe, rapidly destructive arthropathy. These sheep provide a good model for future projects to assess complex methods of surgical reconstruction in cases of deficient bone stock. The sheep in which the cartilage alone was removed developed a moderate, more gradual type of arthritis. These sheep provide a good model for future projects to assess various types of arthroplasties as they might apply to the majority of less destructive arthritic hips, as seen in clinical practice.