Association of bone mineral density with the development of knee osteoarthritis in men and women: a cross-sectional study using the fourth and fifth Korea National Health and Nutrition Examination Surveys

Bone mineral density (BMD) and osteoarthritis (OA) were correlated but the relationship was varied according to sex. An association between lumbar spine and femur neck BMDs and OA showed a positive relation in women, while lumbar spine and pelvis BMDs in men were associated with OA with a negative relation. Purpose The purpose of this study was to evaluate the association of BMD in various body parts in conjunction with the presence or severity of radiographic knee osteoarthritis (KOA) in relation to sex. Methods This study was a cross-sectional analysis using Korea National Health and Nutrition Examination Surveys. KOA was graded using the Kellgren-Lawrence (KL) grading system. Radiographic KOA was defined as a KL grade 2 or higher. The associations between KOA and BMD in certain body parts (femur, pelvis, lumbar, lower leg, and whole-body) were assessed. BMD was measured using dual-energy X-ray absorptiometry. The BMD of each body part was divided into quartiles and the relationship between KOA and BMD was examined according to sex. Results BMD did not show a significant tendency according to KL grade in either sex. In men, the severity of KL grade have a statistically significant relationship with total femur (R-2=0.303, p<0.05), femur neck (R-2=0.257, p<0.05), lumbar (R-2=0.137, p<0.05), and pelvis BMD (R-2=0.185, p<0.05). In women, total femur (R-2=0.466, p<0.05), lumbar (R-2=0.316, p<0.05), pelvis (R-2=0.343, p<0.05), and lower leg BMD (R-2=0.133, p<0.05) were associated with the severity of KL grade. When the BMD was divided into quartiles, lumbar (p<0.05) and pelvis BMD (p<0.05) in men had statistically significant association with knee OA as BMD decreased. In women, femur neck (p<0.05) and lumbar BMD (p<0.05) were significantly associated with knee OA as BMD increased. Conclusion The relationship between BMD and OA severity varied according to sex. In women, there was a positive association between femur neck and lumbar BMD and OA, while BMD of the lumbar and pelvis in men was negatively correlated with OA.