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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_10 | Pages 21 - 21
1 May 2016
Rodgers W Buchele C Kaddick C Schroeder D
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Introduction

Clinically relevant attributes of an orthopedic bearing material include its strength, oxidative stability, and wear resistance. Recent reductions in bearing wear and oxidation have been realized by crosslinking (HXLPE), and through the incorporation of α-tocopherol (VE). VE infusion has improved the oxidative stability of HXLPE in vitro [1] and in vivo (as evidenced by retrievals) [2]. However, concern has been raised that adding VE may increase the frictional torque of bearings, potentially increasing the risk of trunnionosis [3]. This study compares the 3D frictional torques of HXLPE vs Vitamin-E HXPLE, against 28 mm and 36 mm metal and ceramic heads.

Methods

Samples were made from prints for commercially available Ringloc liners (Biomet, IN). The HXLPE group was made from ArCom XL, and the VE-HXLPE was made from E1 HXLPE (Biomet, IN). Femoral heads were of cobalt chrome (ASTM F1537), or ceramic (Biolox Delta™). Testing was performed at EndoLab®, Germany. An ISO 14242–1 compliant six-station simulator and 3D gait cycle was utilized. During the cycle, the abduction/adduction range was −4°/+7°, the flexion/extension was +25°/-18°, and the external/internal rotation was −10°/+2°. Testing was performed at 37±2 °C, at 1 Hz, and with a maximum dynamic load of 3.0 kN. Lubrication medium was calf serum, EDTA, and antibiotics diluted in DI water (30 g/l of protein). Measurements were averaged across 5 cycles after 120 completed cycles of motion, and after 200 cycles. Analysis was performed using Minitab with multiple 2-way ANOVAs, with a p=0.05 significance threshold.