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Highly cross-linked, electron-beam-irradiated, melted polyethylene: some pros
1Department of Orthopaedic Surgery and the Orthopaedic Biomechanics and Biomaterials Laboratory, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA. wharris.obbl@partners.org
Clinical Orthopaedics and Related Research
|December 4, 2004
Summary
Electron-beam highly cross-linked, melted ultra-high molecular weight polyethylene demonstrates excellent wear reduction and oxidation resistance for total hip replacement. This advanced material offers a compelling alternative to traditional bearing surfaces, with over five years of successful in vivo use.
Area of Science:
- Biomaterials Science
- Orthopedic Surgery
- Materials Engineering
Background:
- Ultra-high molecular weight polyethylene (UHMWPE) is a common bearing material in total hip replacement.
- Concerns regarding wear and oxidation resistance of traditional UHMWPE have driven the development of advanced materials.
- Electron-beam irradiation and melting create highly cross-linked UHMWPE with improved properties.
Purpose of the Study:
- To evaluate the clinical performance and material properties of electron-beam highly cross-linked, melted UHMWPE in total hip arthroplasty.
- To compare the wear characteristics of this advanced polyethylene with other bearing surfaces.
- To assess the long-term durability, including oxidation resistance and mechanical integrity.
Main Methods:
- Analysis of extensive new evidence and multiple studies.
- Femoral head penetration measurements using different techniques and demographic groups.
- Examination of retrieval specimens up to 3 years post-implantation.
- Assessment of oxidation resistance and mechanical properties through various studies.
Main Results:
- Femoral head penetration is less than 10 microns per year after the bedding-in period, comparable to metal-on-metal and ceramic-on-ceramic bearings.
- Retrieval analysis confirms minimal wear with persistent machine marks.
- No evidence of oxidation or residual free radicals was found.
- Exceptional fatigue resistance noted, with only three failures attributed to component malposition out of 150,000 cases.
- In vivo durations exceed five years with excellent mechanical properties.
Conclusions:
- Electron-beam highly cross-linked, melted UHMWPE exhibits excellent in vivo wear, oxidation resistance, and mechanical properties for total hip arthroplasty.
- This material presents a compelling alternative to hard-on-hard bearings due to its performance and additional advantages like cost and adaptability.
- The long-term clinical performance supports its widespread adoption in hip replacement surgery.