Taichi Sato

Acoustic pattern evaluation during cementless hip arthroplasty surgery may be a new method for predicting complications

Background: Although surgeons must perform implantation of the cementless stem during total hip arthroplasty (THA) without complications, assessment is left to the surgeon’s intuitive judgement, which could contain inter/intra-observer bias variety. We therefore asked (1) whether the sound created during the stem implantation could be evaluated objectively and (2) whether those sounds are correlate to the complication specific to the cementless stems. Our hypothesis is that the sounds produced during stem insertion could be quantified and related to the complications. Patients and method: In 71 THAs, we quantified the sound produced during stem insertion and investigated the relationship between these sounds and the occurrence of intraoperative fracture and subsidence. Results: The sound data were divided into two patterns: Patterns A and B. The difference between the peak value (dB) at the most common frequency (near 7 kHz) and the second most common frequency (near 4 kHz) of strikes during the final phase of implantation in Patterns A and B showed a significant difference. Adverse events on intraoperative fracture and subsidence were significantly less common in patients with Pattern A than in those with Pattern B (six of 42 hips with Pattern A and 13 of 29 hips with Pattern B, p = 0.004). Pattern A in predicting a clinical course without those adverse events was 69.2% and the specificity was 68.4%. Positive and negative predictive values were 85.7% and 44.8%, respectively. Conclusion: The sound generated during stem insertion was quantified. Those sound patterns were associated with complications.

Control of human generating force by use of acoustic information

We have performed basic experiments for the purpose of applying onomatopoeia to engineering problems. In these experiments, test subjects were made to perform lifting actions while listening to onomatopoeic utterances. We thereby demonstrated that there is a relationship between the onomatopoeic utterances and the lifting forces exerted by the test subjects. We examined how the lifting forces are related to the envelope of onomatopoeic utterances. Furthermore, we investigated how the lifting force is affected depending on whether or not emotion is expressed when uttering the onomatopoeia.

Rotational Vibration of a Spur Gear Pair Having Tooth Helix Deviation: Effect of Lead Modifications

Lead form modification has been used to avoid detrimental effects of tooth helix deviation caused by manufacturing error or misalignment of a gear pair from the viewpoint of tooth strength on gear design. Hence parabolic crowning, elliptic crowning and end relief are adopted conventionally as a typical modified lead form. However the effect of both the shape and the amount of the lead modification on dynamic characteristics of the gear pair has not been made clear enough yet. Using the simulator which was developed by authors and is capable of analyzing vibration response of a pair of spur gear considering tooth surface deviation, the present paper shows that the effect of a proper lead crowning is to maintain the designed dynamic behavior even when tooth helix slope deviation exists, or that is equivalent to misalignment. An optimum form of end relief approximated to that of crowning is determined by the least square method. In addition, since the amplitude of gear vibration is sensitive to the tooth profile error, importance of considering tip relief is presented.© 2003 ASME