Based on CT scans at the 12th thoracic spine level, assessing the impact of skeletal muscle and adipose tissue index on one-year postoperative mortality in elderly hip fracture patients: a propensity score-matched multicenter retrospective study.

BACKGROUND

Research has demonstrated that individuals with sarcopenia or sarcopenic obesity who experience fractures or undergo major surgical interventions exhibit a poorer prognosis compared to the general population. However, few studies have investigated the relationship between the skeletal muscle and adipose tissue indices, as measured at the 12th thoracic spine level, and adverse outcomes following orthopedic surgery. Therefore, this study aimed to prove whether skeletal muscle and adipose tissue index measured by computed tomography (CT) images based on a single layer are associated with one-year postoperative mortality in elderly hip fracture patients.

METHODS

A total of 334 participants from two institutions were enrolled in this study to obtain skeletal muscle index (SMI), subcutaneous fat index (SFI), visceral fat index (VFI), and the visceral-to-subcutaneous ratio of the fat area (VSR) at T12 levels and divide them into death and survival groups based on the results of follow-up after 1 year. Propensity score matching (PSM) was employed to evaluate one-year postoperative mortality.

RESULTS

Institution 1's results identified that a lower SMI significantly heightened the risk of one-year postoperative mortality (OR = 0.799,95%CI 0.677-0.943, P = 0.008), making SMI an independent predictor. Institution 2's results identified that age (OR = 1.081, 95%CI 1.005-1.163, P = 0.036), SMI (OR = 0.881, 95%CI 0.784-0.991, P = 0.035) as independent predictors of one-year postoperative mortality in elderly hip fracture. Receiver operator characteristics analysis revealed area under the curve (AUC) values for institution 1: SMI (0.738 (95%CI 0.626-0.851), significant), VFI (0.605 (95%CI 0.476-0.734)), VSR (0.583 (95%CI 0.451-0.715)); and for institution 2: SMI (0.742 (95%CI 0.612-0.872), significant) and Age (0.775 (95%CI 0.677-0.874), significant). Collectively, these results underscore that SMI serves as an independent predictor of one-year postoperative mortality in elderly hip fracture patients.

CONCLUSION

This study demonstrated that the T12-based SMI was independently associated with one-year mortality following hip fracture in geriatric patients, with lower preoperative SMI correlating with higher mortality rates post-surgery.