Knee and hip radiographic osteoarthritis predict total hip bone loss in older adults: a prospective study

The relationship between osteoarthritis (OA) and osteoporosis remains controversial. This study was designed to determine the association between hip and knee radiographic OA and change in total hip bone mineral density (BMD) over 2.6 years. A total of 867 population-based randomly selected subjects (mean age 62 years, range 51 to 80 years, and 49% female) were included. Hip and knee joint space narrowing (JSN, 0 to 3) and osteophytes (0 to 3) in both lower limbs was assessed using Altman's atlas. Total hip BMD was measured by dual-energy X-ray absorptiometry (DXA). We found that radiographic OA (score of JSN or osteophytes > 0) was common in this sample (hip 45%, knee 68%). In multivariable analyses, percentage change in total hip BMD per year was predicted by right and left hip axial JSN (beta = -0.25% and -0.29% per grade, respectively, both p < .05), right hip superior femoral osteophytes (grades 2 and 3 versus 0: beta = -1.60, p < .05), combined right and left knee tibiofemoral JSN (beta = -0.06 per grade from grades 0 to 12, p < .05), and osteophytes (beta = -0.06 per grade from grades 0 to 14, p < .05) independent of each other and joint pain. In conclusion, older subjects with radiographic hip and knee OA have higher total hip bone loss over 2.6 years regardless of symptoms, suggesting that consideration should be given to the monitoring of bone mass in these subjects.