Abstract
BACKGROUND: The risk of internal fixation failure remains relatively high in stable femoral neck fracture (FNF) (Garden I or II). Preoperative sagittal displacement of the femoral head has been proposed as a potential influencing factor. This study aimed to evaluate the impact of sagittal displacement on the outcomes of cannulated screw internal fixation (CSIF) in patients with stable FNF (Garden I or II) by reconstructing the axial sagittal oblique plane of the fracture using preoperative computed tomography (CT) imaging. METHODS: This study included 167 patients with FNF who underwent CSIF. The sagittal tilt angle of the femoral head (STAFH) was evaluated using three-dimensional CT (3D-CT). The distribution of preoperative STAFH was analyzed, and its independent association with treatment failure was assessed. Treatment failure was defined as the need for revision surgery within 2 years postoperatively due to avascular necrosis, nonunion, or internal fixation failure. RESULTS: Among the 167 patients, 9 (5.4%) exhibited anterior tilt (AT) of the femoral head, 158 (94.60%) presented with posterior tilt (PT). A total of 50 patients (29.9%) demonstrated excessive sagittal displacement (AT ≥ 10° or PT ≥ 20°). In the failure group, 80.0% of patients had excessive sagittal displacement compared to 28.1% in the healed group. Excessive sagittal displacement was significantly associated with an increased risk of surgical failure (odds ratio: 11.953, 95% CI: 3.656-39.083, p < 0.05). CONCLUSIONS: In patients with Garden I or II FNF, greater preoperative sagittal displacement of the femoral head was correlated with a higher likelihood of CSIF failure. AT ≥ 10° or PT ≥ 20° were identified as independent predictors of CSIF failure in FNF patients. Nevertheless, these findings still require confirmation through prospective, multi-center clinical trials with large sample sizes.