Ultra high molecular weight polyethylene: Mechanics, morphology, and clinical behavior

Abstract

Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been used for over four decades as a bearing surface in total joint replacements. The mechanical properties and wear properties of UHMWPE are of interest with respect to the in vivo performance of UHMWPE joint replacement components. The mechanical properties of the polymer are dependent on both its crystalline and amorphous phases. Altering either phase (i.e., changing overall crystallinity, crystalline morphology, or crosslinking the amorphous phase) can affect the mechanical behavior of the material. There is also evidence that the morphology of UHMWPE, and, hence, its mechanical properties evolve with loading. UHMWPE has also been shown to be susceptible to oxidative degradation following gamma radiation sterilization with subsequent loss of mechanical properties. Contemporary UHMWPE sterilization methods have been developed to reduce or eliminate oxidative degradation. Also, crosslinking of UHMWPE has been pursued to improve the wear resistance of UHMWPE joint components. The 1st generation of highly crosslinked UHMWPEs have resulted in clinically reduced wear; however, the mechanical properties of these materials, such as ductility and fracture toughness, are reduced when compared to the virgin material. Therefore, a 2nd generation of highly crosslinked UHMWPEs are being introduced to preserve the wear resistance of the 1st generation while also seeking to provide oxidative stability and improved mechanical properties.

Synthesis of poly(sulfonate ester)s by ADMET polymerization

“…Since the advent of the Ziegler-Natta process in the early 1950s, 1 polyolefins, and particularly polyethylene, have become ubiquitous in applications that range from packaging, 2,3 to implants, 4 to life vests. 5 Polyethylene exhibits tailorable mechanical properties, low cost, and high chemical and biological stability.…”

Short-term Risk of Revision THA in the Medicare Population Has Not Improved With Time

“…Historically, factors related to limitations in implant design and/or manufacturing, including bearing surface wear, osteolysis, and mechanical loosening of the prosthesis, were the primary reasons for revision THA [11,17,18]. Owing to technologic and manufacturing advances, better implants and biomaterials have been developed to improve implant longevity [15,32,33]. The reduction in 5-and 7-year adjusted risks of revision THA likely reflects improvements in THA technology, such as large-diameter femoral heads which may have contributed to a reduction in the risk of dislocation, and the introduction of highly cross-linked polyethylene bearings, which have substantially reduced the risk of wear and osteolysis [15,22,25,33].…”

“…Owing to technologic and manufacturing advances, better implants and biomaterials have been developed to improve implant longevity [15,32,33]. The reduction in 5-and 7-year adjusted risks of revision THA likely reflects improvements in THA technology, such as large-diameter femoral heads which may have contributed to a reduction in the risk of dislocation, and the introduction of highly cross-linked polyethylene bearings, which have substantially reduced the risk of wear and osteolysis [15,22,25,33]. However, despite these advances in implant technology, the shortterm (1 and 3 years) adjusted risk of revision THA has not declined.…”

Study the effect of surface texturing on the stress distribution of UHMWPE as a bearing material during rolling motion

“…Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been used widely as a bearing surface for over four decades in total joint replacements [1]. UHMWPE has great properties such as tough, durable and biological inert [2].…”