Medial versus lateral condyle bone mineral density ratios in a cross-sectional study: a potential marker for medial knee osteoarthritis severity.

OBJECTIVE

To assess the association of bone mineral density (BMD) of the femoral and tibial condyles with knee pain and disease severity in women with symptomatic medial knee osteoarthritis (OA).

METHODS

We enrolled 192 women (ages 41-90 years) between April 2007 and March 2011. The subjects were divided into 2 groups according to joint space narrowing (JSN) on weight-bearing radiographs. BMD of the lumbar spine, proximal femur, and knee condyles was measured. Medial and lateral condyle BMDs of the femur and tibia as well as the medial versus lateral condyle BMD ratios were measured.

RESULTS

Mean medial condyle BMDs, medial versus lateral condyle BMD ratios, and visual analog scale (VAS) pain in both the femur and the tibia were higher in the obliteration group compared with the narrowing group (P < 0.001 for all). A significant positive correlation was observed between the femoral and tibial condyles in the following parameters: medial condyle BMDs, lateral condyle BMDs, and medial versus lateral condyle BMD ratios (r = 0.791-0.844). In both the femur and the tibia, medial versus lateral condyle BMD ratios had significant positive correlations with femorotibial angle, medial osteophytes, lateral osteophytes, medial JSN, and VAS pain, and had significant negative correlations with the Knee Society pain and function scores.

CONCLUSION

Although this study was a cross-sectional study, the femoral and tibial medial versus lateral condyle BMD ratios increased with more severe knee pain and might be a potential marker for monitoring disease severity in women with symptomatic medial knee OA.