Research Activities, January 2014
Loss of bone mineral density over time is associated with progressive cartilage loss in osteoarthritic knees
General bone health appears to influence the ability of bone to stabilize the knee joint affected by osteoarthritis (OA). In fact, a new study reveals that, as bone mineral density (BMD), a measure of bone health, is lost, it is accompanied by progressive cartilage loss in the knee.
Researchers investigated the relationship between BMD changes and the progression of knee OA in 127 patients with knee OA. At baseline, year 1, and year 2, each individual had their BMD measured at the hip by a DXA scanner. During these same time points, magnetic resonance imaging (MRI) was used to measure cartilage volume and thickness in the knee joint.
The average baseline BMD was 0.95 gm/cm2 and the change in BMD per year was -0.004 gm/cm2. A BMD loss of 0.1 gm/cm2 was associated with a cartilage volume loss of 1.25 percent each year. Patients with greater BMD loss (greater than the Least Significant Change) lost an average of 1.02 percent more cartilage volume per year compared to patients with no BMD loss. BMD loss also affected femoral and tibial cartilage thickness. A BMD loss of 0.1 gm/cm2 resulted in a tibial cartilage thickness loss of 0.028 mm each year. Patients with greater BMD loss (greater than the Least Significant Change) lost an average of 0.021 mm more tibial cartilage thickness per year compared to patients without BMD loss.
The researchers call for more research to determine the biologic mechanism behind the relationship between BMD loss and cartilage loss in knees with OA. The study was supported in part by AHRQ (T32 HS00060).
See "Relationship of bone mineral density to progression of knee osteoarthritis," by Ji Y. Lee, M.D., M.S., William F. Harvey, M.D., M.Sc., Lori L. Price, M.A.S., and others in the June 2013 Arthritis & Rheumatism 65(6), pp. 1541-1546.