Evaluating Frictional Temperature Rise in Sliding Surface of Artificial Hip Joint Materials with Different Loading Conditions

Abstract

Friction between articulating surfaces cause temperature rise in acetabular cup and femoral head. This heating may in uence the rate of wear, fatigue, creep, oxidative degradation of bearing materials and may terminate surrounding tissue. The objective of this study is to determine temperature rise with di erent applied load for the articulating surfaces of conventional ultra high molecular weight polyethylene (UHMWPE) and vitamin E blended ultra high molecular weight polyethylene (VE-UHMWPE) acetabular components paired with a ceramic femoral component in bovine calf serum lubrication condition. Additionally frictional torque between the bearing surfaces was measured and friction coe cient was calculated. Frictional measurements of the joints were carried out on a custom made hip joint friction simulator. Various levels of static loads were applied on 28 mm diameter prostheses. In exion-extension plane, a simple harmonic oscillatory motion between ±24◦ was applied to the UHMWPE acetabular component. The period of motion was 1 Hz and the tests were run up to 12,000 cycles. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. The results were compared in terms of UHMWPE and vitamin E blended UHMWPE.