Effect of varying trunnion geometry of hip implant on contact mechanics under walking gait cycle: A finite element study

This study investigates the contact parameters at the trunnion by analyzing the effects of four key geometric factors: distal and proximal chamfer geometry, contact length and surface geometry, and acetabular head diameter, to identify designs that reduce the risk of contact-related failures. The forces are exerted in the F x , F y , and F z directions on hip implant acetabular head. The chamfer cut improve the contact stress distribution, micromotion, and penetration, whereas trunnions without a chamfer exhibit stress concentration that can lead to edge damage and joint failure. Increasing the contact length from 10 to 17.5 mm improves contact stress, micromotion and penetration and contributes to a lower wear rate. The acetabular head diameter variation has very negligible effect on the contact parameters at trunnion. Furthermore, angular mismatches at trunnion create a shielding effect, resulting in contact stress concentration and potential damage at the trunnion edges. Notably, spur gear trunnion models with 4 and 8 teeth show superior performance by reducing sliding distance and wear rate. These findings offer valuable insights for optimizing trunnion design to improve implant longevity and performance.