Biomechanical comparison of proximal femoral nail, dynamic hip screw, monolateral external fixator and cannulated screw in basicervical femoral neck fracture

Aim: The objective of this study was to establish the relative fixation strengths of proximal femoral nail, dynamic hip screw, monolateral external fixator, and cannulated screw in basicervical femoral neck fracture model.Material and Method: The study involved four groups of composite proximal femoral synthetic bones of eight specimens per group; nailing using a PFN, three-hole plating using a DHS, fixation with three cannulated screws in a triangular fashion, and fixation with monoblock trochanteric EF. A 70? osteotomy model was performed to simulate a Pauwels Type 3 basicervical femoral neck fracture. For each specimen, a minimum preload of 100 N was applied before loading to failure. The constructs were subjected to cyclic loading with 16? to midline from 100 N to 1,000 N for 10,000 cycles at 3 Hz. Axial loading was applied at 10mm/min until femur failure. Load to failure, mode of failure, and displacement at load to failure were documented.Results: Mean load to failure was 2182,5±377,9 N in PFN group, 2008,75±278,4 N in DHS group, 1941,25±171,6 N in EF group, and 1551,6±236,2 N in CS group. Average displacement was 15,6±4,5 mm, 15,5±6,7 mm, 11,7±1,9 mm, and 15±1,7 mm, respectively. Any statistically significant difference was not noted among groups for fixation strength. All of the constructs in CS group failed during cyclic loading.Conclusion: Our findings suggest that PFN, DHS and EF restored higher fixation strengths than CS in basicervical femoral neck fracture model. Although there is no significant difference among PFN, DHS, and EF, PFN has higher failure loads and possesses biomechanical benefits for fixation of unstable basicervical femoral neck fractures compared with DHS and EF.