Measurement Method of Femoral Anteversion During Surgery for Trochanteric Fractures

The acceptable range of bilateral differences in the femoral rotation is ≤15°, as a difference in femoral rotation over 15° may cause functional disturbance. However, femoral trochanteric fractures do not have clear indicators of rotation during surgery. This study aimed to verify the accuracy of this novel method for measuring femoral anteversion during trochanteric fracture surgery. From August 2022 to August 2024, this study prospectively included patients with femoral trochanteric fractures treated using a cephalo-medullary nail with a lag-screw neck-shaft angle of 125°. During surgery, direct intraoperative anteversion (DIAV) was measured using the hip post axis in the lateral hip image based on a tabletop plane parallel to the floor. DIAV was then converted to corrected intraoperative anteversion (CIAV) using a quick chart derived from a graph of the axial projection. The accuracy was analyzed by comparing CIAV with computed tomography anteversion (CTAV) measurements obtained after surgery. One hundred patients (25 male, 75 female) with a mean age of 86.7 years (range: 67-104 years) were included in this study. According to the Orthopaedic Trauma Association classification, there were 66 patients classified as A1, 23 as A2, and 11 as A3. The mean DIAV and CIAV were 8.2°±8.2° and 9.6°±9.7°, respectively, while the mean CTAV was 10.3°±10.4°. The median difference between CIAV and CTAV was 3° (range: 0°-9°), with 84 patients exhibiting differences of ≤5°. No significant differences were found between CIAV and CTAV (p = 0.054), whereas DIAV was significantly lower than CTAV (p < 0.001). CIAV and CTAV were strongly correlated (r = 0.936, p < 0.001). The Bland-Altman plot between CIAV and CTAV revealed that 98 patients were within the limits of agreement, and the plot distribution showed no trend. The measurement method for assessing femoral anteversion using the hip post axis on the lateral hip image based on a tabletop plane parallel to the floor during surgery demonstrated sufficient accuracy for indicating anteversion in femoral trochanteric fractures.