Clinical application of modified hip joint lateral position in femoral neck fracture

Abstract

Background To show the femoral neck better in hip lateral view of X-ray, we design a modified hip lateral view, and then investigate the value in femoral neck fractures. Methods CT images of 10 normal hip joints for 3D reconstruction were selected, the Mimics Medical 21.0 were used, and rotating the proximal femur was to find the most suitable angle for showing the femoral neck well, designed the modified lateral view according to this angle. We collected 25 femoral neck fracture and 25 healthy cases for observation and control group. And two groups were all taken hip anteroposterior, cross-table lateral and modified lateral view, which were analyzed by two radiologists to score the anatomical structures of the articular surface, femoral head, subfemoral head region, femoral neck, basal region and intertrochanteric region. Friedman Test was used to analyze the score of femoral neck at different angles. T test and Wilcoxon signed ranks test were to compare inter-groups. Results The modified lateral view was designed as follows: the subjects were supine, with the sagittal axis biased toward the healthy side at an angle of approximately 20° to the long axis of the examination table, the hip joint flexed at 45°, the lower extremity abducted at 40°, the centerline inclined 45° toward the head, and the centerline aligned with the center of the groin. The modified lateral view showed the femoral head, subfemoral head region and femoral neck more clearly than the lateral cross-table view, but the cross-table lateral showed the femoral neck basal and intertochanteric region better. In addition, the time of taking the modified lateral view was significantly less than the cross-table lateral view (healthy group: 0.752min ± 0.161 vs 0.596min ± 0.151, P < 0.001; fracture group: 1.128min ± 0.404 vs 0.924min ± 0.395, P < 0.001). Conclusions The modified lateral view can obtain a standard sagittal image of femoral neck, which can show the dislocation and angulation of the sagittal femoral neck fracture clearly, and improve the accuracy of diagnosis. And it is more convenient and easier for patients to cooperate, which is worthy promoting and applying in clinical work.