Risk of periprosthetic femur fracture after anterior cortical bone windowing: A mechanical analysis of short versus long cemented stems in pigs

BACKGROUND AND PURPOSE: Removal of distal cement at femoral implant revision is technically challenging and is associated with complications such as cortical perforations. A technique that can reduce the risks and operating time is to make a small cortical window in the distal femur for enhanced access. We wanted to determine whether the use of long, bridging, cemented femoral stems is necessary to reduce the risk of postoperative periprosthetic fractures after using an anterior cortical bone window. METHODS: 66 fresh pig femurs underwent mechanical testing. Steel rods were implanted at 3 locations: (1) at the distal window edge, (2) 15 mm proximally to the cortical window edge, and (3) 15 mm distally. 54 femurs were tested using a 3-point bending setup and 12 femurs were tested using a torsional load setup. RESULTS: Load to fracture ratio and bending stiffness ratio were similar in the 3 groups, for either the 3-point bending test or the torsional load test. INTERPRETATION: Our findings suggest that bypass of cortical windows with a revision femoral component may not reduce the risk of periprosthetic fracture.