Inverse determination of the thermal contact conductance for an interface between a Co28Cr6Mo hip stem and a PMMA-based bone cement

Traditional mechanical methods for implant and bone cement removal during total hip arthroplasty (THA) revision surgeries typically lead to surrounding tissue damage and increased risk of femoral fractures. Transcutaneous induction heating is a promising new removal approach as it causes softening of the thermoplastic bone cement, and thus prevents damage to the surrounding tissue during removal and increases stability post-revision. However, precise knowledge of the heat transfer between implant and bone cement is necessary to minimize the risk of thermal damage to surrounding tissues. In this context, knowledge of the thermal contact conductance (TCC) at the interface of Co28Cr6Mo hip stems and PMMA-based bone cement is a key issue. The present study addresses the challenge of measuring TCC by proposing an inverse method of determination using infrared thermography measurements of the heating process and a finite element simulation with a variable parameter for the TCC. Results indicate TCC values of 3,125 +/- 275 Wm- 2K- 1 for dry interfaces and 5,100 +/- 300 Wm- 2K- 1 for wet interfaces. The influence of heat conduction on bone cement surface temperature is significant, impacting the measured surface temperatures by 15-19% for wet and 23-30% for dry interfaces. These findings are crucial for the design of heating procedures and minimization of thermal damage during induction heating assisted THA revisions.