Preoperative computed tomography assessment of peri-hip muscles in patients with femoral neck fracture and its impact on postoperative walking function.

Background: The role of preoperative peri-hip muscles in postoperative walking ability for patients with femoral neck fractures is unclear. This study investigated the influence of these muscles on postoperative walking function using computed tomography (CT).

Methods: A retrospective analysis was conducted on 58 patients (12 male, 46 female) who underwent bipolar hemiarthroplasty for femoral neck fractures between January 2018 and July 2021. Patients were followed up for at least six months postoperatively and categorized into two groups: the independent walking group (41 patients) and the non-walking group (17 patients). Patient data, including sex, age at surgery, body mass index (BMI), and preoperative walking status, were compared. Additionally, preoperative CT scans assessed the cross-sectional areas and CT values of the gluteus medius, gluteus maximus, and rectus femoris muscles on the unaffected side. These measurements were compared between the two groups.

Results: No significant differences were observed between the groups regarding sex, age, BMI, or preoperative walking status. The CT values of the gluteus medius and gluteus maximus were significantly lower in the non-walking group compared with the walking group (gluteus medius: 39.3 ± 7.5 Hounsfield units (HU) vs. 28.6 ± 6.9 HU; P < 0.01; gluteus maximus: 33.0 ± 8.1 HU vs. 23.3 ± 10.7 HU; P < 0.01), whereas no significant differences were found for the rectus femoris. Cross-sectional areas of all muscles did not show significant differences between the two groups. Receiver operating characteristic curve analysis revealed that the gluteus medius had an area under the curve (AUC) of 0.86, with a sensitivity of 0.78 and specificity of 0.82, using a cut-off of 33.1 HU. The gluteus maximus had an AUC of 0.77, with a sensitivity of 0.63 and specificity of 0.77, using a cut-off of 31.6 HU.

Conclusions: Preoperative CT values of the gluteus medius and gluteus maximus were lower in the non-walking group, suggesting that these muscles influence postoperative walking ability. Preoperative CT evaluation of these muscles can be a useful predictor of postoperative walking outcomes.