Vertical shear fractures of the femoral neck - A biomechanical study

A biomechanical cadaver study was performed to compare the strength and sta bility of three cannulated cancellous lag screws with a sliding hip screw f or fixation of a vertically oriented fracture of the femoral neck (Pauwels Type III), Using eight matched pairs of human cadaveric femurs, vertically oriented femoral neck osteotomies were created, reduced, and randomized to one of the two fixation methods. The constructs were tested with incrementa l axial loading front 100 N to 1200 N and cyclical loading at 1000 N for 10 ,000 cycles; fracture displacements and ultimate load to failure were deter mined. The specimens stabilized using a sliding hip screw showed less infer ior femoral head displacement, less shearing displacement at the osteotomy site, and a much greater load to failure than did those stabilized with mul tiple cancellous lag screws, These results support the use of a sliding hip screw for treatment of vertically oriented fractures of the femoral neck.