Incidence and Risk Factors for Femoral Malrotation Following Intramedullary Nailing of Trochanteric Fractures: A CT-Based Analysis.

Objective: To quantify rotational displacement following intramedullary nail fixation for intertrochanteric femoral fractures using three-dimensional (3D) CT imaging, analyze associated risk factors, and evaluate its clinical significance.

Methods: This study enrolled a cohort of 252 patients who underwent intramedullary nail fixation for intertrochanteric femoral fractures between 2019 and 2023. All participants underwent postoperative three-dimensional computed tomography (3D CT) and were followed for a minimum of 1 year. Postoperative femoral anteversion on the affected side was quantitatively assessed. An analysis was conducted to evaluate its correlation with potential risk factors, including age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) classification, nail length, type of internal fixation, reduction quality, AO Foundation/Orthopaedic Trauma Association (AO/OTA) fracture classification, presence of medial cortical defect, bone mineral density (T-score), Singh's index, relative lateral wall thickness (rLWT), tip-apex distance (TAD), neck-shaft angle, and fracture classification. The impact of differences in anteversion on long-term clinical outcomes, including Visual Analog Scale (VAS) pain scores and Harris Hip Scores (HHS), was assessed through follow-up evaluations.

Results: After screening for exclusion criteria, a total of 210 patients were enrolled in the study: 33 patients (15.7%) exhibited differences in anteversion exceeding 15°; 177 patients (84.3%) were under 15°. In the subgroup with version deviations <15°, precise anatomical restoration (anteversion ≤5°) was achieved in 138 cases (77.9%), consistent with optimal biomechanical reconstruction targets; functionally compensated malrotation (5° < anteversion <15°) occurred in 39 patients (22.1%), within the tolerance range for gait adaptation without clinical impairment. Single-nail fixation, medial cortical defects, T-score >2.5, rLWT and fracture classification were identified as the primary factors contributing to rotational displacement exceeding 15°. At the 1-year follow-up, patients with smaller rotational displacement demonstrated better functional recovery, as reflected by improved Visual Analog Scale (VAS) pain scores and Harris Hip Scores (HHS).The multivariate linear regression analysis demonstrated that the rLWT showed significant correlation with rotational displacement of fracture fragments after intramedullary nail fixation.

Conclusion: Bone rotation and displacement are frequently observed following intramedullary nail fixation for intertrochanteric fractures. The rLWT is closely associated with these complications. Therefore, meticulous attention to surgical technique is essential to minimize complications and optimize outcomes.