Symposium: UHMWPE for Arthroplasty: From Powder to Debris 9 articles
History and Systematic Review of Wear and Osteolysis Outcomes for First-generation Highly Crosslinked Polyethylene
Highly crosslinked polyethylene (HXLPE) was introduced to reduce wear and osteolysis in total joint arthroplasty. While many studies report wear and osteolysis associated with HXLPE, analytical techniques, clinical study design and followup, HXLPE formulation and implant design characteristics, and patient populations differ substantially among investigations, complicating a unified perspective.
Highly crosslinked and thermally treated polyethylenes were clinically introduced to reduce wear and osteolysis. Although the crosslinking process improves the wear performance, it also introduces free radicals into the polymer that can subsequently oxidize. Thermal treatments have been implemented to reduce oxidation; however, the efficacy of these methods with regard to reducing in vivo oxidative degradation remains to be seen. Polyethylene oxidation is a concern because it can compromise the ultimate strength and ductility of the material.
Cartilage-mimicking, High-density Brush Structure Improves Wear Resistance of Crosslinked Polyethylene: A Pilot Study
In natural synovial joints under physiologic conditions, fluid thin-film lubrication by a hydrated layer of the cartilage is essential for the smooth motion of the joints. The considerably less efficient lubrication of artificial joints of polyethylene is prone to wear, leading to osteolysis and aseptic loosening and limiting the longevity of THA. A nanometer-scale layer of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) with cartilage-mimicking brushlike structures on a crosslinked polyethylene (CLPE) surface may provide hydrophilicity and lubricity resembling the physiologic joint surface.
Osteolysis due to wear of UHMWPE limits the longevity of joint arthroplasty. Oxidative degradation of UHMWPE gamma-sterilized in air increases its wear while decreasing mechanical strength. Vitamin E stabilization of UHMWPE was proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength.
Crosslinked UHMWPE as a bearing surface in total joint arthroplasty has higher wear resistance than conventional UHMWPE but lower strength and toughness. To produce crosslinked UHMWPE with improved mechanical properties, the material can be treated before crosslinking by tension to induce molecular alignment (texture).
Do Tissues From THA Revision of Highly Crosslinked UHMWPE Liners Contain Wear Debris and Associated Inflammation?
Polyethylene wear debris is a major contributor to inflammation and the development of implant loosening, a leading cause of THA revisions. To reduce wear debris, highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) was introduced to improve wear properties of bearing surfaces. As highly crosslinked UHMWPE revision tissues are only now becoming available, it is possible to examine the presence and association of wear debris with inflammation in early implant loosening.
Crack Propagation Resistance Is Similar Under Static and Cyclic Loading in Crosslinked UHMWPE: A Pilot Study
Recent work suggests crack phenomena (eg, crack initiation and propagation) in UHMWPE do not depend on cyclic damage mechanisms. Materials for which crack phenomena occur in static (noncyclic) mode should exhibit similar crack propagation behavior under static and cyclic loading conditions.
Ultrahigh-molecular-weight polyethylene (UHMWPE) is used as an articulating surface in prosthetic devices. Its failure under various mechanisms after oxidation is of utmost concern. Free radicals formed during the sterilization process using high-energy irradiation result in oxidation. Europium, an element of the lanthanide family, has a unique electron configuration with an unusual lack of preference for directional bonding and notable bonding to oxygen. Because of this, it currently is used in studies for stabilization of polymers such as polyvinyl chloride.