Variation in applied force during insertion of cemented femoral prostheses

Information is presented on forces applied to cemented prostheses during insertion. An instrumented femoral pusher was used to collect information during simulated operations on cadavers while using a laboratory test rig and during live surgery. Surgeons using flanged or collared prostheses tend to apply more force than those using collarless prostheses. There is a tendency for abrupt changes in applied force to occur when: 1) clearing cement; 2) easing hand discomfort; and 3) testing cement consistency. Tests showed that an overall impression of the force applied could be obtained from a laboratory simulation, but that clearing cement and testing cement were not modelled by this method. We discuss the implications of our observations in terms of prosthesis fixation and training of staff.