关键词: 股骨颈骨折, 骨折固定术, 有限元分析, Pauwels分型

Abstract: Objective To investigate the biomechanical properties and clinical outcomes of four-screw configuration used for internal fixation of Pauwels type Ⅲ femoral neck fractures.Methods A three-dimensional finite element model (FEM) of Pauwels type Ⅲ femoral neck fracture was established and analyzed in three fixation groups (Group 1, an inverted triad of screws; Group 2, four-screw configuration with one transverse screw and three parallel inverted triangle screws; Group 3, hybrid fixation of one dynamic hip screw and one de-rotation screw).Simulated load with one leg standing was applied and then the stress and displacement of the model were calculated to compare the biomechanical stability of different fixation strategies.Retrospective clinical analysis of 31 cases with Pauwels type Ⅲ femoral neck fractures using four-screw fixation was conducted.Results Biomechanically, finite element analysis showed that the strongest construct for stabilizing a Pauwels type Ⅲ femoral neck fracture was Group 3, followed in descending order by Group 2 and Group 1, and the screw displacement in descending order was Group 3, Group 2, and Group 1.Clinically, 31 patients with Pauwels type Ⅲ femoral neck fractures were treated with four-screw configuration; 24 patients (77.4%) were followed up for 24 months and over (24-62 months).None of the cases was nonunion and the mean union time was 16.3 weeks (12-24 weeks).Three cases (12.5%) had necrosis of femoral head.The mean Harris score of hip function was 80±8.5 points, and the excellent-and-good rate was 83.3%.Conclusion The four-screw configuration with one transverse screw and three parallel inverted triangle screws can be used to fix Pauwels type Ⅲ femoral neck fracture.Further studies with larger sample size and longer follow-up are required to assess its clinical efficacy.

Key words: Femoral neck fractures, Fracture fixation, Finite element analysis, Pauwels classification