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 inuence 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 dierent 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 coecient 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.

Effect of synovial fluid temperature on wear resistance of different polymer acetabular materials

“…Bergmann 21 Polyethylene cups 43.1°C Pritchett 22 Synovial fluid 47°C Roussignol 23 Polyethylene cups 52.65°C Lu 29 Polyethylene cups 51.3 ± 5.2°C Bergmann 30 Synovial fluid 46°C Rocchi 31 CoCrMo femoral head 51°C…”

“…A related study found that the in vivo hip prosthesis femoral head temperature could reach 43°C after one hour of walking, 21 and there was a significant increase in the synovial fluid temperature near the hip prosthesis after 1 hour of walking, with a temperature rise of up to 7°C in the ceramic ball on the synovial fluid near the polyethylene hip prosthesis. 22 When polymeric acetabular materials are used for a long time in a high temperature environment, they accelerate their own oxidation process, 23 which affects their wear resistance. Saikko et al 24 investigated the effects of lubricant serum type and synovial fluid temperature on the frictional behavior of VE-XLPE under mating with CoCr and found that the average wear coefficient of VE-XLPE decreases significantly as the synovial fluid temperature increases from low to 37°C.…”