Abstract
Background
We have often experienced a change of the tone of the hammering sound during the press-fit implantation of cementless acetabular components in total hip arthroplasty (THA). The tone of the impact sound before the press-fit of acetabular components seems to differ from the tone after the press-fit. This change of tone may depend on the accuracy of the fit of the acetabular component, or it may simply be a subjective perception. The aim of this study is to evaluate the impact sounds in the press-fit implantation of cementless acetabular components.
Methods
The hammering sounds in press-fit implantation of acetabular components were studied intraoperatively in 22 patients (28 hips) who underwent primary THA for treatment of advanced osteoarthritis. All operations were performed via the direct anterior approach in a supine position. The hemispherical titanium-alloy acetabular component (TriAD; stryker) was implanted in all patients. A sound level meter (NA-28; RION) was used to record and analyze the sounds. The hammering sounds of the first three hits and last three hits were recorded as the “before press-fit” and “after press-fit” sound samples, respectively. A frequency analysis was then performed at the point of peak sound pressure in each sample.
Results
The dominant frequency of the impact sounds was equal to or lower than 1 kHz in 20% of the before press-fit samples and 76% of the after press-fit samples, and equal to or higher than 4 kHz in 69% of the before press-fit samples and 21% of the after press-fit samples. The frequency of the impact sounds changed significantly (p<0.01) during the press-fit implantation.
Conclusion
The frequency of the impact sound changed significantly during the press-fit implantation of cementless acetabular components. We conclude that an intraoperative evaluation of the impact sound might help to improve accuracy when implanting the acetabular component.
