Contact Pressure, sliding distance and wear rate analysis at trunnion of hip implant for daily Activities: A finite element approach

This research analyses contact pressure, sliding distance, and wear rate at the trunnion interface of hip implants during various activities to understand post-hip replacement outcomes. The study uses a numerical model and ISO-7206–6:2013 constraints with an AML hip implant. Greater F_x, F_y, and F_z forces broaden contact pressure distribution. The highest pressure occurs on the proximal superolateral surface, with the lowest on the anterior and posterior surfaces. The HIGH100 (individuals weighing above 100 kg) weight category demonstrates 2 times higher maximum and average contact pressure compared to AVG75 (individuals weighing 75 kg) for sit-down and knee bend activities. Force components and the duration of a full gait cycle influence sliding distance. Stance activities show the highest sliding distance due to rapid changes in force load during the gait cycle. For sit-down and knee bend activities, the total sliding distance is 2.5 times higher in the HIGH100 weight category compared to AVG75. Sliding distance primarily occurs at the proximal superolateral-inferomedial-anterior-posterior contact surface, decreasing distally. Based on contact pressure, sliding distance, and wear volume rate, jogging and stance activities pose the highest risk for hip replacement patients, while cycling is the safest. The HIGH100 weight group exhibits 5- and 4-times greater wear volume rates than AVG75 in sit-down and knee bend activities, respectively. The research findings align with wear degradation observed in retrieved hip implants, validating the study. These insights can assist patients in making informed decisions about performing activities after surgery while enabling physicians to provide accurate guidelines.