The importance of proximal cement filling of the calcar region: a biomechanical justification.

Clinical studies have suggested that a thicker proximal medial cement mantle improves the long-term outcomes of cemented femoral components. A 3-dimensional finite element model was used to determine the effect that replacement of proximal medial trabecular bone with cement has on cement mantle stresses. With removal of cancellous bone in the calcar region, there was a decrease in peak cement mantle stresses by approximately 20%. The greatest reduction in cement mantle stress was seen after cancellous bone was removed from the proximal medial aspect of the femur to a distance 30 mm distal to the femoral neck resection. Under fatigue loading conditions simulating gait, removal of proximal medial cancellous bone could increase the number of loading cycles to failure by a factor of 3.5. These results support the removal of proximal medial cancellous bone from the calcar region intraoperatively to increase the cement mantle thickness and reduce cement mantle stresses to improve the long-term fixation of cemented femoral components.