Cross-linking to improve THR wear performance.

Polyethylene wear and associated osteolysis can limit the longevity of total hip replacement. In recent years, many improvements have been made in the consolidation, manufacture, and sterilization of polyethylene acetabular components. These improvements provided reduced polyethylene wear and prolonged usefulness of total hip replacement. Recent advances in extensively cross-linking polyethylene offer the possibility to substantially further reduce wear in total hip replacement. Hip simulator wear testing demonstrates an order of magnitude reduction in wear resulting from cross-linking GUR 1050 polyethylene by exposure to 100 kGy of electron beam radiation followed by annealing to encourage cross-linking and to reduce residual free radicals. Clinical investigation will be required to validate the wear advantage of these materials in vivo. (Hip International 2002; 2: 103-7).

Micromechanisms of fatigue crack initiation and propagation in bone cements.

The micromechanisms of fatigue fracture in bone cements were explored and characterized in this investigation. Fatigue crack initiation sites were identified and the microscopic features responsible for crack initiation are illustrated. Differences in the fracture morphology of PMMA beads, in early crack growth and rapid crack growth stages, are brought out. Based on the fractographic features, a micromechanism of PMMA bead fracture is proposed.