PERIARTICULAR OSTEOPOROSIS IN OSTEOARTHRITIS OF THE KNEE

Objective. To test the hypothesis that bone mineral density (BMD) in p eriarticular subchondral regions of the knee joint is abnormal in pati ents with osteoarthritis (OA). Methods, Sixty-two knees from patients with relatively mild OA (primarily radiographic grades 0, 1, 2) of the knee were compared with 62 knees from normal subjects matched for age , sex, race, and body side (right or left). BMD of the lumbar spine, d istal femoral shaft, and several periarticular subchondral regions of the knee were determined by dual energy x-ray absorptiometry (DXA). To facilitate increased accuracy of BMD values, lateral DXA of the knees was also performed and used to provide a third dimension to the usual two-dimensional anterior-posterior g/cm(2), producing measurements as g/cm(3). Subchondral bone regions included both superficial and deep regions of the medial femoral, medial tibial, and lateral tibial compa rtments. Results. BMD (g/cm3) was lower than normal in 6 subchondral b one regions of the knees (n = 43) of white female patients with OA (av erage decrease -13.3%), significant in all 6 subchondral regions (p = 0.001 to p = 0.047). Two-dimensional BMD (g/cm2) was lower than normal in 6 subchondral regions of the knees (n = 43) of white female patien ts with OA (average decrease -7.3%), significant in only 2 of 6 subcho ndral regions (p = 0.011 to p = 0.014), BMD (g/cm3) was lower than nor mal in 6 subchondral regions of the knees (n = 19) of African American female patients with OA (average decrease -9.1%), significant in only one of the 6 subchondral regions (p = 0.016). There was no significan t difference in spinal BMD (L1-L4) or femoral shaft BMD between normal and OA for either racial group. About 13% of the OA patients had oste oporosis at the spine, Conclusion. A significant decrease in periartic ular subchondral BMD is present in female patients with relatively mil d OA of the knee whether or not they had osteoporosis based on a spine BMD measurement.