Correlation of preoperative ultrasound quantitative parameters of the quadriceps femoris with new-onset frailty after hip replacement in elderly patients with femoral neck fracture

Objective To investigate the correlation between preoperative ultrasound quantitative parameters of the quadriceps femoris and new-onset frailty after hip replacement in elderly patients with femoral neck fracture. Methods A total of 180 elderly patients with femoral neck fracture who were scheduled to undergo hip replacement and were admitted to Hebei Cangzhou Hospital of Integrated Traditional Chinese and Western Medicine from January 2023 to January 2025 were enrolled as the study subjects (excluding those with preexisting frailty or pre-frailty). On the first day of admission, the thickness of the quadriceps femoris (QMT) and muscle echo intensity of the affected side were measured by ultrasound examination. At the first follow-up visit at 1 month after surgery, frailty phenotype (FP) was used to assess postoperative new-onset frailty status, and the patients were assigned into a frailty group and a non-frailty group according to the assessment results. SPSS statistics 26.0 was used for statistical analysis. Intergroup comparison was performed using t test orχ² test depending on data type. Binary logistic regression model was applied to analyze the factors influencing frailty at 1 month after surgery, and ROC curve was drawn to evaluate the value of preoperative echo intensity of the quadriceps femoris and QMT in predicting the frailty of patients at 1 month after surgery. Results Among the 180 patients, 79 cases (43.89%) were diagnosed with frailty at 1 month after surgery. The frailty group exhibited significantly higer preoperative echo intensity of the quadriceps femoris and lower QMT than the non-frailty group (P<0.05). Taking whether frailty occurred at 1 month after hip replacement as the dependent variable (Y:no=0, yes=1), binary logistic regression analysis suggested that age ≥80 years (OR=2.675,95%CI 1.822-3.928 ), Charlson comorbidity index (CCI) ≥4 points (OR=3.117,95%CI 1.409-6.895), postoperative delirium (OR=2.044,95%CI 1.100-3.798), and preoperative echo intensity of the quadriceps femoris (OR=1.972,95%CI 1.093-3.557) were risk factors, while time to initiation of functional exercise <5 d after surgery (OR=0.513,95%CI 0.328-0.804) and preoperative QMT (OR=0.560,95%CI 0.361-0.869) were protective factors (P<0.05). ROC curve analysis indicated that when the cutoff value of echo intensity was 27.81 AU, The AUC value for predicting frailty at 1 month after surgery was 0.766 (95%CI 0.697-0.836), with a sensitivity and a specificity of 0.810 and 0.594, respectively; when the cutoff value of QMT was 1.98 cm, the AUC value was 0.777 (95%CI 0.710-0.845), with a sensitivity and a specificity of 0.835 and 0.663, respectively; the combination of echo intensity and QMT yielded an AUC value of 0.854 (95%CI 0.799-0.909), with a sensitivity and a specificity of 0.835 and 0.772, respectively. Conclusion In elderly patients with femoral neck fractures, the incidence of frailty at 1 month after hip replacement is relatively high. Preoperative echo intensity of the quadriceps femoris and QMT are independent factors influencing postoperative frailty. Additionally, the 2 indicators and their combination have good value in predicting postoperative frailty, The 2 indicators are expected to become potential indicators for predicting postoperative frailty in patients after hip replacement.