Biomechanical study of medial buttress plate combined with cannulated compression screws for pauwels type III femoral neck fractures using formalin-fixed human cadaveric femora.

PURPOSE: To investigate the biomechanical advantages of medial buttress plate (MBP) combined with inverted triangle cannulated compression screws (CCS) in the internal fixation of Pauwels type III femoral neck fractures.

METHODS

Twelve formalin-fixed human cadaveric femora were used to construct Pauwels type III femoral neck fracture models and were randomly assigned to two groups: CCS group and CCS + MBP group (n = 6 per group). After standardized internal fixation procedures, axial compression, torsional stiffness, and failure load were tested using a Bose ElectroForce 3510 biomechanical testing system, and all measurements were recorded. Differences between groups were analyzed with independent-samples t-tests, with statistical significance set at P < 0.05.

RESULTS

Compared with the CCS group, the CCS + MBP group demonstrated significantly higher axial stiffness (562.95 ± 88.26 N/mm vs. 171.02 ± 44.98 N/mm), torsional stiffness (3.24 ± 0.43 N·m/° vs. 2.28 ± 0.51 N·m/°), and failure load (2523.08 ± 432.71 N vs. 1567.88 ± 209.96 N) (P < 0.05 for all).

CONCLUSION

The combination of MBP and CCS provides significantly greater mechanical stability than CCS alone in Pauwels type III femoral neck fractures. This construct disperses shear forces, improves resistance to axial and rotational loading, and increases failure load. These findings provide biomechanical evidence that may support future investigations of fixation strategies for vertically unstable femoral neck fractures.