Bone Mineral Density and Fatty Degeneration of Thigh Muscles Measured by Computed Tomography in Hip Fracture Patients

BACKGROUND Recently, as an independent fracture factor from Bone mineral density (BMD), muscle weakness due to the fatty degeneration of thigh muscles have been attracting attentions as causes of hip fracture. The purpose of this study is to investigate the correlation between the body composition and BMD and fatty degeneration of thigh muscles of the female patients over 65 years old with osteoporotic hip fracture. METHODS This study was conducted with 178 female osteoporotic hip fracture patients. Total hip BMD was measured using dual energy X-ray absorptiometry. Cross-sectional area (CSA), cross-sectional muscle area (CSmA), muscle attenuation coefficient (MAC), and intramuscular adipose tissue (IMAT) of gluteus maximus, hip abductors, quadriceps and hamstring muscle were measured with computed tomography. Normalized IMAT (nIMAT) was calculated by dividing the fat area in the muscle into the size of each muscle. The correlation between each measurement is examined then the differences between the intertrochanteric fracture group and the femoral neck fracture group were analyzed. RESULTS CSmA and MAC of quadriceps were the largest and nIMAT was the lowest. CSA and CSmA of the four muscles showed a statistically significant positive correlation with weight, height, body mass index (BMI), and BMD. MAC of 2 gluteal muscles was positively correlated with weight, BMI and BMD. nIMAT of all four muscles was positively correlation with weight and BMI but nIMAT of 2 mid-thigh muscles was positively correlation with BMD. CONCLUSIONS Muscle size and fatty degeneration in the thigh muscles were most positively correlated with the body weight. BMD was positively correlation with CSA and CSmA of all thigh muscles, and MAC of 2 gluteal muscles and fatty degeneration of 2 mid-thigh muscles. There was no statistically significant difference in the size of the femoral muscle and the degree of fatty degeneration between the two fracture groups.