Open Access Research article

Quantification of structural changes of UHMWPE components in total joint replacements

Petr Fulin12*, David Pokorny12, Miroslav Slouf3, Martina Nevoralova3, Tatana Vackova3, Jiri Dybal3 and Jan Pilar3

Author Affiliations

1 Department of Orthopaedics, First Faculty of Medicine, Charles University in Prague, V Úvalu 84, Prague 5 15006, Czech Republic

2 University Hospital Motol, V Úvalu 84, Prague 5 15006, Czech Republic

3 Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06, Prague 6, Czech Republic

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BMC Musculoskeletal Disorders 2014, 15:109  doi:10.1186/1471-2474-15-109

Published: 28 March 2014

Abstract

Background

At present time the number of implantations of joint replacements as well as their revisions increases. Higher demands are required on the quality and longevity of implants. The aim of this work was to determine the degree of oxidative degradation and the amount of free/residual radicals in selected ultra-high molecular weight polyethylene (UHMWPE) components of the joint replacements and demonstrate that the measured values are closely connected with quality and lifetime of the polymer components.

Methods

We tested both new (4 samples) and explanted (4 samples) UHMWPE polymers for total joint replacements. The samples were characterized by infrared spectroscopy (IR), electron spin resonance (ESR) and microhardness (MH) test. The IR measurements yielded the values of oxidation index and trans-vinylene index. The ESR measurements gave the free radicals concentration.

Results

In the group of new polyethylene components, we found oxidation index values ranging from 0.00-0.03 to 0.24. The trans-vinylene index values ranged from 0.044 to 0.080. The value of free radical concentration was zero in virgin and also in sample of Beznoska Company and non-zero in the other samples. In the group of explanted components, the measured values were associated with their history, micromechanical properties and performance in vivo.

Conclusions

We demonstrated that measuring of oxidative damage may help the orthopaedic surgeon in estimating the quality of UHMWPE replacement component and thus radically to avoid early joint replacement failure due to worse polyethylene quality.

Keywords:
UHMWPE; Oxidative damage; Residual radicals; Infrared spectroscopy; Electron spin resonance