Nomenclature

With emerging minimally invasive surgical techniques in total hip arthroplasty, there has been an increase in fractures associated with the insertion of the prosthesis into the femur. Diminished visibility necessitates a greater emphasis on the surgeon’s tactile and auditory senses to ascertain the femoral component position, ensuring maximum stability and interference fit and prevention of further component impaction and subsequent fracture of the femur. Because of the smaller incision, it is not possible to take measurements directly on the bone. Measurements must therefore be taken proximally on the femoral component. The work described in this study attempts to identify a means to supplement the surgeon’s tactile and auditory senses by using damage identification techniques normally used in civil and mechanical structures to monitor the insertion process of the prosthesis. It is hypothesized that vibration characteristics of the impact process may be used intra-operatively to determine at what position the femoral component has reached maximal interference fit and stability in the femur, referred to as “seating. ” Such information can be used to prevent further impacts and potential fracture. An ICP accelerometer was used to monitor the impact process. This paper summarizes features derived from the measured data that will be used to develop a dynamic seating indicator