Analysis of the gluteus medius muscle atrophy and fat infiltration in young adults after femoral neck fracture surgery: A retrospective volumetric and composition computed tomographic analysis.

Gluteus medius (GMED) muscle atrophy after femoral neck fracture surgery is common and can contribute to gait abnormalities. This retrospective study aimed to evaluate the changes in muscle volume and intramuscular adipose tissue following osteosynthesis. This retrospective study included 33 patients who underwent osteosynthesis for femoral neck fracture between April 2010 and April 2022. Bilateral hip computed tomography scans were analyzed at 5 time points: preoperative, immediate postoperative, early postoperative, intermediate postoperative, and late postoperative. Three-dimensional volumetric and muscle-to-adipose tissue ratio analyses were performed. The GMED muscle volume on the fractured side decreased by up to 20% and remained reduced by 10% even 1 year after surgery, with a 1.6 times higher muscle-to-adipose tissue ratio than that on the uninjured side. These findings suggest that GMED atrophy and compositional changes persist for more than a year, even in young healthy patients, potentially affecting their long-term gait and hip function.