Formulation and selection of composite biomaterials for acetabular cup of hip prosthesis with wear analysis

The study of tribological performance of metal-on-plastic type of hip prostheses has drawn the attention of researchers since the last few decades. These studies mainly focus on the friction and wear behaviour of acetabular cups made of different polymer biomaterials with a view to enhance the prostheses life. In this study, a novel biomaterial coded as LHHA has been prepared for the acetabular cup in three different blends with help of bioprocess engineering by mixing low-density polyethylene and high-density polyethylene with10, 20 and 30 percent of hydroxyapatite to improve the mechanical properties. A popular decision-making method was applied to select the best alternative from these three blends on the basis of hardness, roughness and ultimate strength and LHHA-30 is found to be the best. Furthermore, experimental wear investigation was carried out in a well-designed hip simulator to control such biological system under a series of random loads, within 600N and 1500N acting at different points on prosthesis for 10 million gait cycles run followed by theoretical wear analysis. Wear rates are found to be 12.651 and 26.247 mg per million cycle with marginal differences of 0.1 and 0.6 for LHHA-30 and ultrahigh molecular weight polyethylene (UHMWPE) acetabular cups against cobalt–chromium (Co–Cr) alloy femoral head, respectively. Morphological studies carried out by scanning electron microscope revealed that LHHA-30 scored less compared to UHMWPE surface.