Exploring the Effectiveness of "Four-Point" Configuration Cannulated Compression Screw Implantation Protocol for the Fixation of Pauwels Type III Femoral Neck Fractures in Adults.

BACKGROUND

Pauwels type III femoral neck fractures (P3FNFs) are one of the common types of femoral neck fractures (FNF) caused by high-energy violent factors. This study aims to evaluate the efficacy of inverted cannulated cancellous screw (ICCS) assisted transversal cannulated screw (TCS) perpendicular to the fracture line in young adults with Pauwels type III femoral neck fractures.

METHODS

Construct an internal fixation-fracture model through finite element analysis (FEA) and biomechanical test (BT) to simulate the stress environment of the human hip joint, and utilize the femoral neck system (FNS) model as a control to predict the biomechanical properties of ICCS + TCS. From January 2023 to December 2024, 21 patients with P3FNFs treated with ICCS + TCS were collected, and their recent radiographic and clinical outcomes were evaluated. The experimental data underwent statistical analysis using one-way ANOVA and independent samples t-test.

RESULT: ICCS + TCS exhibits biomechanical trends in FEA and BT that are essentially consistent with those of FNS. ICCS + TCS has stronger torsional stiffness and lower overall deformation, But the resistance to vertical shear force is weaker than FNS. All patients in this study successfully completed the surgery without complications such as vascular or nerve injuries. The follow-up period ranged from 8 to 25 months. The hip joint flexion-extension ROM, internal-external rotation ROM, and Harris score all significantly increased (p < 0.05). The shortening length of the femoral neck was 3.87 ± 0.44 mm.

CONCLUSION

ICCS + TCS exhibits biomechanical trends compared to FNS; meanwhile, it has stronger torsional resistance and load-bearing deformations. Simultaneously, ICCS + TCS has demonstrated favorable outcomes in clinical treatments. This study offers a novel approach for the treatment of P3FNFs.