Biomechanical comparison of different locations for a proximal femoral window: A cadaver study.

BACKGROUND

In revision hip arthroplasty, changing a cemented stem is a challenging procedure, as a femoral window is often necessary to achieve total cement removal. The aim of this biomechanical study was to compare the stability of different locations for a proximal femoral window.

METHODS

Thirty-six macerated human cadaver femora were assigned to one of the six groups: ventral window with square or rounded corners; lateral window with square or rounded corners; and dorsal window with square or rounded corners. Starting at the middle of the lesser trochanter, a window 1.6 × 10 cm in size was sawed in a distal direction. The biomechanical properties of the femora were measured using a materials testing machine in axial loading at a fixed displacement rate of 20 mm/min.

FINDINGS: The mean failure strength did not differ significantly between the groups (ventral window: square corners 6688 N, rounded corners 5391 N; lateral window: square corners 2889 N, rounded corners 4402 N; dorsal window: square corners 5082 N, rounded corners 3626 N) (P = 0.08). The number of fractures through the window differed significantly between the groups (ventral window: square corners 3, rounded corners 0; lateral window: square corners 5, rounded corners 5; dorsal window: square corners 5, rounded corners 2) (P = 0.01).

INTERPRETATION: Lateral locations of the proximal femoral window were associated with the largest number of fractures through the window, and ventral locations with the smallest number. Surgeons may therefore consider using a ventral window when changing a cemented stem in revision hip arthroplasty.