Association of computed tomography-based radiodensity of the peri-hip muscles with hip fracture type and severity: a retrospective study in middle-aged and elderly patients

Sarcopenia and myosteatosis—hallmarks of aging associated with reduced muscle quality and function—can be assessed using computed tomography (CT)-based measurements of muscle cross-sectional area and radiodensity. This study quantitatively compared CT-measured cross-sectional area and radiodensity of peri-hip muscles among patients with non-displaced femoral neck, displaced femoral neck, and intertrochanteric fractures. In total, 279 patients were retrospectively analyzed and categorized into three groups: non-displaced femoral neck fractures (n = 89; 63 women, 26 men), displaced femoral neck fractures (n = 101; 65 women, 36 men), and intertrochanteric fractures (n = 89; 52 women, 37 men). Cross-sectional area and radiodensity were measured on cross-sectional CT images: the gluteus medius and minimus at the level inferior to the sacroiliac joint, the gluteus maximus at the acetabular roof, and the quadriceps femoris and medial thigh muscles inferior to the lesser trochanter. No significant differences in sex, age, or cross-sectional area of peri-hip muscles were observed among the three groups. Significant differences were found in radiodensity of the gluteus maximus, medius, minimus, and medial thigh muscles but not in the quadriceps femoris (P = 0.001, P < 0.001, P < 0.001, P = 0.010, and P = 0.212, respectively). Post-hoc analyses showed significantly lower radiodensity in the gluteus medius, minimus, and medial thigh muscles in both displaced femoral neck and intertrochanteric fracture groups than in the non-displaced femoral neck fracture group (P = 0.008, P = 0.006, P = 0.020; P < 0.001, P < 0.001, P = 0.024; respectively), with the gluteus maximus also lower in the intertrochanteric group (P = 0.001). Our study demonstrated that CT-measured peri-hip muscle radiodensity differs significantly among hip fracture types and severity. Specifically, higher radiodensity (reduced muscle fatty infiltration) was associated with non-displaced femoral neck fractures compared with displaced femoral neck or intertrochanteric fractures.