Investigation of Bone Resonance during Femoral Reaming in Hip Replacement Surgery

This paper documents current investigations which are attempting to find a suitable audio pattern to identify the moment when a prosthetic hip-joint replacement has been correctly inserted into the thigh bone. Research Questions: We have two objectives: first is there any distinctive pattern of sound frequency or resonation associated with proper femoral rasping? Second: can we predict the point where fracture of the femur during the rasping process occurs using the analysis of the sound frequency changes? Initial research into this project has noted that by placing a bone conduction microphone close to the knee of the patient, the resonances of the thigh bone can be detected as the joint is reamed into place. A distinct increase in the pitch of the resonance can be noted as the joint reaches its correct position. It is proposed that by collecting and analysing a suitably large database of audio recordings of the rasping process, that a prediction model for when the joint is optimally reamed into position can be created. It must be noted that, as each femur will be of different size/density, each rasping process will yield different results. Therefore analysis will have to be undertaken to create a model which will prove reliable for all cases.