Clinical study on the incidence of femoral head posterior tilt angle in non-displaced femoral neck fractures

Abstract

To investigate the occurrence of posterior femoral head tilt after clinical non-displaced femoral neck fracture, and to provide a reference basis for clinical surgery and improvement of disease prognosis. Total of 165 patients with non-displaced femoral neck fractures of Garden typeⅠandⅡfrom January 2018 to June 2022 were selected as study subjects including 48 males and 117 females, with an average age of (71.5±8.5) years old ranging from 53 to 89, involving 97 cases of typeⅠand 68 of typeⅡ. On the patient's preoperative sagittal or axial CT film of the hip, the angle formed by the radius line of the femoral head and the midline of the femoral neck was used as the posterior tilt angle of the femoral head (α), and the posterior tilt femoral head angle was measured using the method proposed by Palm. The measured data were divided into 6 groups:α<0°, 0°<α< 5°, 5°≤α<10°, 10°≤α<15°, 15°≤α<20°, α≥20°, and the incidence of different ranges of posterior tilt angle was compared. The sex composition ratio of 165 patients were analyzed and compared, and the age of 65 was used as the cut-off point to compare the incidence of fractures between genders. Patients were divided into the posterior tilt <20° group for 135 cases and the posterior tilt ≥20°group for 30 cases according to the preoperative posterior tilt angle, the differences between two groups in terms of gender and age were analyzed. Among 165 patients with non-displaced femoral neck fractures, 143 cases with poaterior tilt of the femoral head occurred with an incidence of 86.7%. Posterior tilt 0°<α<5° accounted for 36 cases with an incidence of 21.8%;5°≤α<10° accounted for 40 cases with an incidence of 24.2%;10°≤α<15° accounted for 27 cases with an incidence of 16.4%;15°≤α<20° accounted for 10 cases with an incidence of 6.1%;posterior tilt angle α≥20° accounted for 30 cases, the incidence was 18.2%, of which the maximum posterior tilt angle was 42.7°. Statistical analysis showed that the percentage of fractures in the 165 patients selected for this study was significantly higher in female than in male, and that the female group was more likely to have fractures before the age of 65 years compared to the male group. However, gender, age and fracture subtypes (GardenⅠ, Ⅱ) were not influential factors for femoral neck fractures with a preoperative posterior femoral head tilt angle >20°(P>0.05). The incidence of femoral head posterior tile in non-displaced femoral neck fractures is relatively high, in which severe posterior tile occurs, and the femoral head posterior tile angle≥20° can reach 18.2%. In patients with closed reduction internal fixation, the fracture end needs to be repositioned as much as possible to reduce the risk of postoperative avascular necrosis of the femoral head. In order to prevent femoral neck fractures, special attention should be paid to anti-osteoporosis treatment for female. Preoperative assessment of posterior tilt is critical for patients of different ages, genders and fracture subtypes (GardenⅠ, Ⅱ).