Comparative fatigue behavior and toughness of remelted and annealed highly crosslinked polyethylenes.

Abstract

Highly cross-linked polyethylenes (HXLPEs) have been incorporated into the hip replacement armamentarium based on their improved wear resistance. However, two different methods of thermal treatment separate the orthopedic community as strategies to control potential long-term oxidation, and controversy remains with problems in the long-term use of acetabular liners (long-term oxidation, rim fracture after impingement, etc.). Meanwhile, the mechanical properties of HXLPEs that may alleviate these problems are still unclear. On the other hand, HXLPEs are scarcely used in knee replacements, as there exists concern about the probably reduced fatigue and fracture performances of these materials. Thus, our aim was to compare the effects of both thermal treatment regimes on mechanical properties and to associate these findings with the material microstructure. The fatigue behavior of annealed and remelted HXLPEs was characterized using short-term cyclic stress-strain, long-term fatigue, and fatigue crack propagation tests. On the other hand, impact tests, tensile experiments, and the J-integral multispecimen method allowed us to assess toughness. Microstructure features such as crosslink density, crystallinity percentage, and lamellar thickness were investigated by swelling measurements, differential scanning calorimetry, and transmission electron microscopy, respectively. This study confirms that annealing preserves mechanical properties better than remelting from both fatigue and fracture resistance points of view, and it remarks that a suitable selection of irradiation and stabilization conditions is needed to achieve optimal mechanical performances of ultra high molecular weight polyethylenes for each specific total joint replacement.

• Authors: Francisco J Medel, P Peña, José Cegoñino, E Gómez-Barrena, J A Puértolas
• Journal: Journal of biomedical materials research. Part B, Applied biomaterials (J Biomed Mater Res B Appl Biomater) Vol. 83 Issue 2 Pg. 380-90 (Nov 2007) ISSN: 1552-4973 [Print] United States
• PMID: 17680670 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Biocompatible Materials
• Polyethylenes
• ultra-high molecular weight polyethylene

Topics

• Biocompatible Materials (chemistry)
• Hot Temperature
• Humans
• Joint Prosthesis
• Polyethylenes (chemistry, radiation effects)
• Stress, Mechanical
• Tensile Strength