Bone mineral density and osteoarthritis: data from the Baltimore Longitudinal Study of Aging.

Background: Numerous cross-sectional studies have shown that persons with radiographic features of osteoarthritis (OA) of the hips and knees have higher adjusted levels of bone mineral density (BMD).

Objective: Data from the Baltimore Longitudinal Study of Aging were examined to determine (1) whether persons with radiographic features of OA of the hands and knees had different rates of bone loss than subjects with normal knee radiographs, and (2) whether persons with normal knee radiographs who had higher adjusted levels of BMD were at greater risk of developing radiographic features of knee OA.

Design: Longitudinal cohort study.

Subjects: 298 Caucasian men and 139 Caucasian women aged 20 and above who had radiographs of the hands and knees read for features of OA and two or more measurements of BMD at the forearm at least 4 years apart. 179 Caucasian men and 110 Caucasian women aged 20 and above who had longitudinal knee radiographs on average 10 years apart, a subgroup of whom had baseline measurement of lumbar spine and/or femoral neck BMD.

Results: Women with radiographic OA of the hand had a significantly greater adjusted rate of bone loss at the radius than women with normal hand radiographs; no such differences were noted in men for hand OA. There were no significant differences in adjusted rate of bone loss at the radius in men or women by presence of radiographic knee OA. Higher BMD at the lumbar spine but not at the femoral neck was associated with an increased risk of developing incident radiographic knee OA after adjustment for age, gender, and body mass index.

Conclusions: These data demonstrate that persons with radiographic OA lose bone at different rates than those with normal radiographs and that this relationship varies between the site of OA and the site of measurement of BMD. In addition, they further support a role for higher bone mass in the development of radiographic knee OA. Further studies are needed to examine the relationship between changes in bone mass and radiographic progression of OA.