The in vitro Measurement of Bone-Cement Interface Pressures and Shear Strengths in the Femur: A Comparison of two Cementation Methods

Two differing cementation methods were investigated in an in vitro simulation of hip arthroplasty.

The bone-cement interface pressures were recorded during cement injection and stem insertion in matched pairs of fresh cadaveric femora. Reduced viscosity cement injected with a cement gun and proximal seal was compared with injection of high viscosity cement and finger-packing in each pair. The resultant shear strength of the bone-cement interface was measured by push-out tests. Results were analysed using the Wilcoxon ranked sum test for paired samples.

The Exeter method of cementation produced significantly higher mean and maximum pressures above the bleeding pressure of femoral bone at all interface levels during cement injection. This was associated with significantly greater mean shear strengths. The authors conclude that the Exeter pressurization system for cementation overcomes the effect of femoral bone bleeding and improves the quality of the bone-cement interface. This may contribute to reduction in the incidence of loosening in cement hip arthroplasty.