Radiographic Thigh Muscle Measurements Are Independently Associated with 1-Year Mortality Following Hip Fracture Surgery.

Background: Geriatric hip fractures remain associated with significant mortality and morbidity. Identifying factors associated with such outcomes is an important step for improvement of prognostication and supporting individualized care. Sarcopenia is a known risk factor for mortality and thigh muscle measurements on plain radiographs can serve as a proxy measure of sarcopenia. Therefore, the objective was to determine whether radiographic thigh muscle measurements were independently associated with 1-year mortality following hip fracture surgery. Methods: All consecutive patients aged 70 years or older undergoing operative treatment for an isolated hip fracture at 2 urban Level 1 trauma centers between 2018 and 2020 with preoperative radiographs displaying the distal-and-middle femur were included. Thigh muscle diameter and soft tissue size was measured on anteroposterior and lateral radiographs using standardized anatomical landmarks. Multivariable logistic regression was performed to determine if there were independent associations with 1-year mortality for the variables assessed. Inter-rater reliability for each measurement was evaluated by calculating intraclass correlation coefficients (ICCs). Results: One hundred ninety-nine patients (median age 85 years, 68% female) were included. One-year mortality was 22%. After adjusting for age, sex, smoking status, preinjury living situation, Charlson Comorbidity Index, frailty, and body mass index, a greater thigh muscle diameter on anteroposterior radiographs was associated with lower odds of 1-year mortality (adjusted odds ratio 0.74, 95% confidence interval 0.56-0.97, p = 0.028). There was no significant association with thigh muscle diameter on lateral radiographs or with total soft tissue diameter on anteroposterior or lateral radiographs. The ICCs demonstrated good-to-excellent reliability for all radiographic measurements. Conclusion: Greater thigh muscle diameter measured on anteroposterior radiographs was independently associated with decreased 1-year mortality following hip fracture surgery, with each centimeter increase in diameter being associated with an average reduction in odds of 26%. This finding should be interpreted in the context of the limited sample size, homogenous patient population, and range of observed thigh muscle sizes. Overall, these results suggest that radiographic parameters may potentially serve to complement currently used modalities, such as frailty assessment, in supporting individualized care. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.