Bone Density, Dynamic Joint Loading and Joint Degeneration

Increased joint loading and elevated bone density may be involved in the initiation or progression of osteoarthritis. Here, we provide an introduction to the literature on this topic and describe recent studies from our laboratories on several cohorts of subjects who had or were scheduled to have a total hip replacement for unilateral end-stage osteoarthritis. This population is very useful for studying the development and progression of osteoarthritis because of the known higher incidence of osteoarthritis in the contralateral hip than in a normal population. Separate studies of the asymptomatic contralateral hip in these subjects have shown that radiographic signs of early osteoarthritis are associated with increased bone mineral density and some of the gait adaptations typically found in subjects with end-stage osteoarthritis. We have also shown in separate studies of similar populations that elevated bone mineral density is associated with a subsequent accelerated joint space narrowing rate and that elevated hip joint loads during gait are similarly associated with an accelerated narrowing rate. Major questions yet to be answered are how joint loading and bone density interact in the development and progression of joint degeneration.