Spectral analysis of the sound produced during femoral broaching and implant insertion in uncemented hip arthroplasty

IntroductionDuring broach preparation and implant insertion of the proximal femur the surgeon may be able to use audible pitch changes to judge broaching adequacy and implant position. The aim of this study was to analyse the sound produced and explain the sound spectra using acoustic physics.MethodsA highly sensitive microphone was used to digitally record the sound made during femoral preparation and definitive implant insertion in 9 patients undergoing total hip arthroplasty. The sound data was analysed using a fast Fournier transformation spectrum analyser. The highest 4 peak spectral amplitudes of the first broach, the last strike of the final broach and the definitive implant were recorded. The sound spectra produced by striking the implant introducer in isolation were analysed in a similar manner.ResultsAnalysis of the sound spectra identified the appearance of a low frequency peak (mean 892Hz) during final broaching that was not present when using the first broach. This occurred in 6 of the 9 case...