Ortho Plastics The Adoption and Evolution of Polyethylene in Orthopedic Surgery

Total joint arthroplasty relies on the use of biomaterials that are biologically inert and capable of forming wear-resistant articulating surfaces. Polyethylene use in arthroplasty has become ubiquitous since its introduction in the 1960s. Early arthroplasty procedures of the hip utilized poly-tetra-flouroethylene, or "Teflon," due to its low coefficient of friction that was presumed to closely mimic the hyaline cartilage of native joints. Early catastrophic wear of Teflon caused a significant local tissue reaction contributing to osteolysis, aseptic loosening, and clinical failure ultimately limiting the material's surgical utility. Advancements in biomaterial synthesis and processing led to the fortuitous discovery of ultra-high-molecular-weight-polyethylene (UHMWPE) and the eventual evolution to highly cross-linked polyethylene (HXLPE) as a bearing surface in hip arthroplasties with robust, long-term clinical success. Ultra-high-molecularweight-polyethylene was readily adopted for use in total knee arthroplasty following the material's successful use in hip replacement, however, the unique biomechanics of the knee have posed unique challenges. The use of HXLPE in knee arthroplasty has increased, however, clear data regarding its benefit over UHMWPE are conflicting. Recently, clinical as well as research and development studies of UHMWPE and HXLPE have focused on alternative postprocessing methods to optimize material stability and wear resistance. Second generation HXLPE utilizing sequential annealing processes or vitamin E to stabilize free radicals are promising means to improve mechanical stability and wear resistance for use in joint arthroplasty, however, more data is required to evaluate long-term outcomes and cost-effectiveness. In this review, we discuss the history and innovation of polyethylene use in orthopedic surgery and evaluate the current literature on outcomes of polyethylene use in hip and knee replacement.