Abstract
In total hip arthroplasty, judgment of the appropriateness of stem hammering is dependent on the experience and feelings of the surgeon and no objective evaluation method has been established. In this study, a frequency analysis of the hammering sounds in total hip arthroplasty was performed to investigate objective judgment criteria capable of preventing problems during surgery. Stem hammering was applied following the surgeon’s feelings as usual in an operating room. A directional microphone was placed at a distance about 2 m from the surgical field and the peak frequency reaching the maximum amplitude was determined by Fourier analysis. It was clarified that the same peak frequency repeats when appropriate fixation is acquired during surgery, suggesting that intraoperative fracture and postoperative loosening can be prevented by stopping hammering at the time the peak frequency converged. Investigation of changes in the hammering sound frequency may serve as objective judgment criteria capable of preventing problems during surgery.
Highlights
In cementless fixation of total hip arthroplasty, when hammering counts are not sufficient, fixation failure, such as loosening, is of concern [1, 2]
There are two analysis methods of externally observing the inner structure of objects: the vibration analysis method in which vibration is added to an object and the vibration frequency is analyzed, and the acoustic analysis method in which the frequency of sounds generated by hitting an object is analyzed [8, 9]
Hypothesizing that specific changes in the frequency occur when fixation between the stem and femur is acquired and stopping hammering at this point prevents intraoperative fracture and loosening, we investigated objective judgment criteria capable of preventing intraoperative fracture and loosening by hammering sound analysis
Summary
In cementless fixation of total hip arthroplasty, when hammering counts are not sufficient, fixation failure, such as loosening, is of concern [1, 2]. When the hammering frequency is increased to prevent fixation failure, the risk of intraoperative fracture increases [3]. Many cases of intraoperative fracture caused by excess hammering have been reported and the incidence is 28%, being high [4,5,6,7]. In the vibration analysis method, an accelerometer is set to the object and vibration acceleration is measured and analyzed. Accurate analytical results are acquired, because the vibration of the analytical object is directly detected, being advantageous, but setting an accelerometer to the object is necessary, being disadvantageous [10]. Sounds generated by the object are collected using a microphone and analyzed [11, 12]. Sine sounds propagate through the air and it is not necessary to set a device to the object, being advantageous
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