Tribological performances of a novel biopolymeric material HD-HA for hip joint implants

Abstract

Most of the modern hip joint implants prefer MoP pairs over MoM, where Co-Cr alloy and UHMWPE are commonly used as femoral head and socket respectively. In such implants, the durability of UHMWPE component is not up to the mark due to severe wear. This study presents better tribological performance of a novel bio-polymeric material coded as HD-HA prepared from HDPE and hydroxyapatite. In the first part, wear tests showed the specific wear rates of 4.85 × 10⁻⁶ and 5.27 × 10⁻⁶ mm³/N-m for HDPE and UHMWPE respectively, whereas it is 3.19 × 10⁻⁶ mm³/N-m for HD-HA. Comparison revealed that HD-HA got 60-65% lower wear rate than others. Similarly in the second part, the friction coefficient is found to be 0.23 and 0.11 for UHMWPE and HDPE respectively and 0.06 for HD-HA, which shows 20% to 50% decrease in frictional values. AFM images revealed that rough peaks are 296, 486, and 1100 nm for HD-HA, HDPE, and UHMWPE respectively; whereas the SEM images show fewer loose particles around worn HD-HA surface. This shows HD-HA has smoother surface and based on the overall tribological performance, it should be preferred for acetabular component of hip joint implants.