Hemiarthroplasty is an attractive technique for young and active patients as it preserves more bone stock. Polycarbonate urethane (PCU) has recently been introduced as an alternative bearing material. DSM Biomedical BV (Geleen, The Netherlands) has modified Bionate® PCU 80A (80AI) with C18 groups and produce Bionate® II PCU 80A (80AII) to create a different biointerface and enhance its tribological properties. The aim of this study was to compare friction performance of the articulation of the cartilage against 80AI and 80AII in various lubricants. A customised multidirectional pin-on-plate reciprocating rig (Fig. 1) was used to perform friction tests of ovine femoral condyles as they articulated against PCU 80A discs (diameter 38 mm, thickness 3.2 mm). The average surface roughness of the cartilage and the PCU discs was approx. 450 nm and 10 nm respectively. 30% (v/v) bovine calf serum (BCS) and bovine synovial fluid (BSF) were used as lubricants. Prior to testing, each disc was fully hydrated in its test lubricant for 6 days. During testing, a static compressive load of 20 N was applied (an average stress of approx. 0.95 MPa). The sliding distance was 25 mm with ±15° rotation over the length of the stroke to produce cross shear. Each test lasted 15 h at a frequency of 1 Hz. Lubricant was kept at 37±1 °C throughout testing. The friction force was measured using full-bridge circuit strain gauges (Fig. 1).Introduction
Materials and Methodology
