変形性膝関節症における下肢筋量と前腕骨密度の関連

抄録

Objective: To assess the association between muscle volume of lower limbs and forearm bone mineral density (BMD) in a population with knee osteoarthritis (OA).

Methods: A total of 682 women (average age: 55.7±15.0 years old) who participated in the Iwaki Health Promotion Project 2015 were recruited. Radiographs of both knee joints were evaluated by Kellgren-Lawrence (KL) grade and those with KL grade 2 or more in severity were defined as OA of the knee. A total of 107 women (average age: 70.2±7.5 years old) who had bilateral OA of the knee were recruited as the study subjects. The muscle volume of each lower limb was measured by a digital composition analyzer, and it was calculated by the summed value of both legs (kg). BMD of the forearm (g/cm²) was measured by dual-energy X-ray absorptiometry at the radius of the non-dominant hand. BMD was evaluated by the region of interest at 1/3 of the distal radius. Knee symptoms were evaluated by the Knee injury and Osteoarthritis Outcome Score (KOOS) Pain scale. Multiple regression analysis was conducted with muscle volume of the lower limbs as dependent variable, and age, height, weight, KL grade, prevalence of menopause, KOOS pain, and BMD as independent variables.

Results: The mean value of muscle volume and BMD in subjects was 11.6±1.4 kg and 0.51±0.08 g/cm², respectively. In a multiple regression model, BMD was significantly associated with muscle volume of the lower limbs (B=2.531; β=0.142; P=0.019).

Conclusion: BMD correlated with muscle volume of the lower limbs in an elderly population with radiographic bilateral OA of the knee.