BONE MASS IN OSTEOARTHRITIS

Present evidence tends to support the hypothesis that bone mass is increased in osteoarthritis of the hip. It is not yet clear whether this is a direct relation or a secondary effect, perhaps due to increased body weight. Evidence for an increase in bone mass in primary generalised osteoarthritis is more equivocal. If radiographic studies are included (although strictly their subjects cannot be labelled as having primary generalised osteoarthritis) then evidence tends to favour an association with an increase in bone mass. The extent of this increase, its distribution throughout the body, its clinical significance, and the roles of obesity and mobility await further investigation. An increase in bone mass in osteoarthritis independent of obesity, if proved, would lend support to the concept of osteoarthritis as a bone disease resulting in secondary damage to cartilage. Whether osteoarthritis protects against osteoporosis, or osteoporosis and its associated risk factors reduce the risk of osteoarthritis also remains to be determined.