Ultra-high molecular weight polyethylene. The material and its use in total joint implants.

History and Systematic Review of Wear and Osteolysis Outcomes for First-generation Highly Crosslinked Polyethylene

“…Difficulty in controlling the tolerances of early metal-on-metal hips has been hypothesized to result in seizure of some metal bearings culminating in early loosening [72], whereas first-generation alumina components were prone to unacceptably high fracture rates [141]. Orthopaedic manufacturers clinically introduced carbon-fiber-reinforced UHMWPE (Poly II TM ; Zimmer, Inc, Warsaw, IN) [1,33,143] and high-pressure crystallized UHMWPE (Hylamer 1 ; DePuy Orthopaedics, Inc, Warsaw, IN) [23,86] in the 1970s and 1980s, respectively. Both of these attempts at polyethylene innovation also failed to win clinical acceptance due to shortterm failures.…”

“…Polyethylene used in orthopaedics was subjected to greater scrutiny than ever before in terms of its manufacturing processes, sterilization techniques, wear mechanisms, and degradation chemistry. Research studies from this time period identified poor consolidation during manufacturing, wear, and poststerilization oxidation of polyethylene as key factors limiting the longevity of total joint arthroplasties [81,86,113,119,145]. As a result, a number of improvements were implemented in the 1990s for the way medical-grade polyethylene was used in orthopaedics.…”

“…As a result, a number of improvements were implemented in the 1990s for the way medical-grade polyethylene was used in orthopaedics. These changes included improvements in the production of the resin or powder by no longer including calcium stearate [81,96,124,130], manufacturing process optimization by compression molding and ram extrusion to eliminate consolidation defects [81,86,87,115], and a shift away from gamma sterilization in air to either gas sterilization or gamma sterilization in a low-oxygen environment [16,30,31,81,96,105,113,117,118,128,129,136]. In retrospect, among these advancements, the transition away from gamma sterilization in air was perhaps the most meaningful in terms of prevention of short-term oxidation-related failures observed in knee arthroplasty [32,93].…”

Behavior of Hylamer polyethylene in hip arthroplasty: comparison of two gamma sterilization techniques

“…In in-vitro tests Hylamer was claimed to have better wear qualities than conventional ultra-high-molecular-weight polyethylene [9], although there was no universal agreement [13]. Other in-vitro studies showed that the wear resistance of Hylamer and conventional polyethylene sterilized by gamma irradiation in air was comparable [13].…”

Is Polyethylene Still the Best Prosthetic Bearing Surface?

“…UHMWPE oxidises more rapidly after sterilisation by gamma irradiation, and preliminary studies, using pin-ondisc machines, have shown that this may allow an increase in wear (Li and Burstein 1994;Fisher et al 1995). There is also some concern about other effects of gamma irradiation.…”