Factors Influence on the Broaching Hammering Sound during Cementless Total Hip Arthroplasty

Abstract

Background: The aim of this study is to identify the factors influence on the broaching hammering sound character during cementless total hip arthroplasty. Methods: We analyzed frequency spectrum of the hammering sound for 49 cases of uncomplicated cementless THAs using two types of proximal-coated stem performed by experienced surgeons. Normalized sound pressure (NSP) of each 0.5 kHz frequency band in final stage of broach procedure was determined by the fast Fourier transform analysis. The relationships between those sound characteristics and femoral morphology such as canal calcar ratio (CCR), Canal flare index (CFI), morphological cortical index (MCI) and femoral shaft length (FSL) in different cementless stem were investigated. Results: In Accolade 2, CCR was positively related to NSP in several bands [Frequency band (kHz); r: 2.0 - 2.5; 0.37, 4.5 - 5.0; 0.37, 9.5 - 10.0; 0.44], and negatively related to 7.5 - 8.0 kHz (r = -0.39). Negative correlations were observed among CFI and MCI in specific frequency bands (4.5 - 5.0, 5.0 - 5.5, and 7.5 - 8.0 kHz). In Taperloc Microplasty, strong correlations were found between FSL and the NSP of 7.5. - 8.0 kHz (r = 0.78) and CCR and the 7.5 - 8.0 kHz bands. There was significant difference of NSPs between high and low group divided by morphological parameters. Acoustic characteristics of NSPs between Accolade 2 and Microplasty were significantly different in 9 frequency bands. Conclusions: The hammering sound correlated with four parameters of the femoral morphology and differed in different types of proximal-coated stem. Those novel five factors are important to consider when to predict complications using acoustic analysis.