Interfragmentary motion assessment for three different fixation techniques of femoral neck fractures in young adults

BACKGROUND: Vertical femoral neck fractures in the youth could be happened in high-energy accidents, and because of dominant shearing forces, this fracture is considered as a troublesome injury with a controversy regarding selection of the best fixation method. OBJECTIVE: The long term goal of this quasi-experimental study was to find the more stable fixation method among cannulated screws (CSs), proximal femoral locking plate (PFLP), and dynamic hip screw with derotational screw (DHS+DS) for this kind of fracture. METHODS: Twelve fresh-frozen cadaveric femurs were assigned to three groups that were matched for mean bone mineral density and stiffness of intact bone. Vertical fractures were artificially mimicked in the specimens and fixed using three different implants, i.e. CSs, PFLP, and DHS+DS. Then, the samples were tested under incremental, cyclic, and failure loading phases. RESULTS: The differences in all biomechanical parameters were statistically significant among tested groups (p < 0.05). All biomechanical parameters for the DHS+DS method of fixation are significantly different from those corresponding to CSs (p < 0.05). There were no significant differences in failure load and failure energy between the PFLP and CSs techniques (p > 0.05). Also, there were no significant differences in relative stiffness and femoral head displacement between the PFLP and DHS+DS groups (p > 0.05). CONCLUSIONS: Based on the clinical assumption that restricted weight-bearing regimen is recommended in the postoperative rehabilitation protocol, the results of this study suggest that the priority order of selection for the stable fixation implant of vertical femoral neck fracture in young patients is DHS+DS, then PFLP, and finally CSs.