Development of a Novel Revison Total Hip Arthroplasty Method for Femoral Component Extraction

Abstract

Revision total hip arthroplasty is an expensive, arduous procedure where a femoral implant must first be removed and then replaced. The most difficult part of this procedure is the removal of the hip implant, without damaging the host bone. To make this process easier, it is proposed that a device could utilize an implant's natural frequency to propagate cracks in the bone cement used to bond the implant to the host bone. The foci of this thesis is to (i) determine the natural frequency of an implant, (ii) design a device that can be easily used in a surgical setting while efficiently transferring vibration energy into an implant, and (iii) show that the vibrational energy can be used to propagate cracks in the cement mantel. To validate these foci both in silico and in vitro methods have been used. In silico models have been designed to determine an implant's natural frequency and to show that low amplitude mechanical vibrations can be used to propagate cracks in the cement mantel. In the in vivo study an initial design has been proposed and successfully prototyped and calibrated to output vibrations to the proper frequency. In order to keep the proposed design safe for surgical use, it has been designed such that internal stresses are less than the yielding stress of bone, and in order to facilitate crack propagation, the crack must first be externally nucleated by the operator.