Biomechanics of bone cement augmentation with compression hip screw system for the treatment of intertrochanteric fractures

Abstract

Recently, cement augmentation technique was introduced to enhance screw fixation within the femoral head. This study investigates biomechanical efficacies of cement augmentation technique. Finite element models of the femur with sliding hip screw assemblies were constructed with and without bone cement augmentation. Appropriate contact conditions with varying friction coefficients were assigned to simulate the fracture planes and other interfacial regions. With cement augmentation, 80% reduction in stresses was found in the cancellous bone, suggesting reduced possibility of cancellous bone fracture and screw cut-outs. The peak von Mises stress within the cement mantle was about 1/3 of its fatigue strength, which suggested the longevity of the cement mantle and less likelihood of osteolysis due to cement debris. Micromotions at the hip screw interfaces were also dwon from 0.275mm to 0.008mm, an indication for strong fixation after the surgery. © Springer-Verlag Berlin Heidelberg 2004.