Non-Invasive Early Detection of Failure Modes in Total Hip Replacements via Acoustic Emission Techniques

Total hip replacements (THR) are becoming increasingly common in the United States (332K/year in 2017) to relieve pain and improve the mobility of those that are affected by osteoarthritis, ankylosing spondylitis, or injury. However, complications like tribocorrosion, or material degradation due to friction and corrosion, may result in implant failure. Unfortunately, few strategies to noninvasively diagnose early-stage complications are reported in literature, leading to implant complications being detected after irreversible damage. Therefore, specific aim 1 of this study proposes the utilization of acoustic emission (AE) to continuously monitor implant materials, CoCrMo and Ti6Al4V, and identify degradations formed during cycles of sleeping, standing, and walking by correlating them to friction and potential behavior. Through the results, higher friction and AE activity was observed in Ti6Al4V alloys while there was also a significant drop in potential, indicating increased tribocorrosion activity. The correlation between friction, potential, AE activity was further confirmed through profilometry which showed more material degradation in Ti6Al4V than CoCrMo. Specific aim 2 of this study utilizes computational modeling to evaluate the influence of biological layers present between the degradation signal source and AE sensor placed on the skin. To utilize AE in clinical studies and obtain accurate data, signal attenuation caused by the presence of biological layers must be better understood. Therefore, our study is significant because it evaluates detected AE activity directly at the location of material degradation and in a computational in vivo model with biological tissues present. Through these evaluations, it was shown that acoustic emission can be utilized to identify the deformations and failure modes of implant materials caused by tribocorrosion.