The present paper provides a review of the properties of UHMWPE for total joint replacement and of some key features of its The present paper provides a review of the properties of UHMWPE for total joint replacement and of some key features of its
technology. The first paragraphs describe the basic physical and chemical properties of UHMWPE, as well as the main processing technology. The first paragraphs describe the basic physical and chemical properties of UHMWPE, as well as the main processing
and sterilisation methods. The following paragraphs are devoted to the chemical processes that lead to oxidative degradation and sterilisation methods. The following paragraphs are devoted to the chemical processes that lead to oxidative degradation
of the polymer, to its practical outcomes and to the contemporary strategies of packaging which aim to minimize this drawback. of the polymer, to its practical outcomes and to the contemporary strategies of packaging which aim to minimize this drawback.
Finally, the causes and the effects of wear and debris production are examined and, in the last sections, recent advances Finally, the causes and the effects of wear and debris production are examined and, in the last sections, recent advances
and future developments in crosslinking and stabilization are briefly described. and future developments in crosslinking and stabilization are briefly described.
[Show abstract][Hide abstract] ABSTRACT: 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.
We reviewed the preclinical research on the development and testing of vitamin E-stabilized UHMWPE with the following questions in mind: (1) What is the rationale behind protecting irradiated UHMWPE against oxidation by vitamin E? (2) What are the effects of vitamin E on the microstructure, tribologic, and mechanical properties of irradiated UHMWPE? (3) Is vitamin E expected to affect the periprosthetic tissue negatively?
We performed searches in PubMed, Scopus, and Science Citation Index to review the development of vitamin E-stabilized UHMWPEs and their feasibility as clinical implants.
The rationale for using vitamin E in UHMWPE was twofold: improving oxidation resistance of irradiated UHMWPEs and fatigue strength of irradiated UHMWPEs with an alternative to postirradiation melting. Vitamin E-stabilized UHMWPE showed oxidation resistance superior to that of irradiated UHMWPEs with detectable residual free radicals. It showed equivalent wear and improved mechanical strength compared to irradiated and melted UHMWPE. The biocompatibility was confirmed by simulating elution, if any, of the antioxidant from implants.
Vitamin E-stabilized UHMWPE offers a joint arthroplasty technology with good mechanical, wear, and oxidation properties.
Vitamin E-stabilized, irradiated UHMWPEs were recently introduced clinically. The rationale behind using vitamin E and in vitro tests comparing its performance to older materials are of great interest for improving longevity of joint arthroplasties.
Clinical Orthopaedics and Related Research 12/2010; 469(8):2286-93. DOI:10.1007/s11999-010-1717-6 · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Highly crosslinked UHMWPE has become the bearing surface of choice in total hip arthroplasty. First generation crosslinked UHMWPEs, clinically introduced in the 1990s, show significant improvements compared to gamma sterilised, conventional UHMWPE in decreasing wear and osteolysis. These crosslinked UHMWPEs were thermally treated (annealed or melted) after irradiation to improve their oxidation resistance. While annealing resulted in the retention of some oxidation potential, post-irradiation melted UHMWPEs had reduced fatigue strength due to the crystallinity loss during melting. Thus, the stabilisation of radiation crosslinked UHMWPEs by the diffusion of the antioxidant vitamin E was developed to obtain oxidation resistance with improved fatigue strength by avoiding post-irradiation melting. A two-step process was developed to incorporate vitamin E into irradiated UHMWPE by diffusion to obtain a uniform concentration profile. Against accelerated and real-time aging in vitro, this material showed superior oxidation resistance to UHMWPEs with residual free radicals. The fatigue strength was improved compared to irradiated and melted UHMWPEs crosslinked using the same irradiation dose. Several adverse testing schemes simulating impingement showed satisfactory behaviour. Peri-prosthetic tissue reaction to vitamin E was evaluated in rabbits and any effects of vitamin E on device fixation were evaluated in a canine model, both of which showed no detrimental effects of the inclusion of vitamin E in crosslinked UHMWPE. Irradiated, vitamin E-diffused, and gamma sterilised UHMWPEs have been in clinical use in hips since 2007 and in knees since 2008. The clinical outcome of this material will be apparent from the results of prospective, randomised clinical studies.
International Orthopaedics 02/2011; 35(2):215-23. DOI:10.1007/s00264-010-1161-y · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We can encounter products made from UHMWPE in many different areas of utilization. This material is used in plastic bearings, ball-and-socket joints, heavy-duty plastic cog-wheels and joint implants. The UHMWPE is a very particular polymer, the special characteristics of which can be attributed to its molecular structure. The ulra-high molecular weight has an effect on wear-resistance, creep-resistance and hardness. These are the parameters demanded by the highly specialized utilization. On the other hand, this molecular stucture also has disadvantages next to the many advantages. Its greatest disadvantage is that it’s difficult to process. The UHMWPE is a thermoplastic, but because of the long molecular chains its injection molding is impossible. In the course of the present research work we will compare the mechanical and quality properties of products made with lathe machining (RAM extrusion) and direct compression molding. We will examine the impact of the changes of the manufacturing and technological parameters. We will be placing a special emphasis on the surface quality because the quality and life-span of the abovementioned products (bearings, ball-and-socket joints, artficial joints) largely depends on this parameter. Besides this we will examine the changes of hardness and the stability of size. In view of these results we will try to determine what would be the best manufacturing technology that could ensure the maximum performance and life-span of these products. [1,3,6] We are focusing by having the results, to optimizing the manufacturing.
Materials Science Forum 03/2013; 752:233-240. DOI:10.4028/www.scientific.net/MSF.752.233
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