Artikel
In vivo change of elastic property in polyethylene acetabular components
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Autoren
Veröffentlicht: | 19. Oktober 2004 |
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Gliederung
Text
Introduction
There have been few detailed reports that referred to the effect of oxidative degradation on the elastic property of the PE cups. We evaluated the elastic property change of the PE cups after the implantation.
Methods
Fifty-six UHMWPE cups retrieved at the revision surgery were evaluated. Thirty-two cups (resin type: GUR412) were sterilized by gamma irradiation and 24 cups (resin type: GUR415) were sterilized by ethylene oxide gas. The years in situ was 7.2 (3.4 to 13.2) in irradiated cups, and 7.7 (2.4 to 14.2) in non-irradiated cups. We measured compression modulus, viscoelasticity, and Vickers hardness of the cups. As a control, six cups aged in shelf in each type were examined.
Results
The compression modulus value in the irradiated cups was 1237 (847-1581) N/mm (control: 976-1513). The value was 1064 (1048-1087) in non-irradiated cups (control: 1042-1050). The viscoelasty (in tangent delta value) was 0.051 (0.038-0.092) (control: 0.040-0.061) in the irradiated cups and was 0.060 (0.050-0.068) (control: 0.60-0.072) in the non-irradiated cups. The Vickers hardness value was 7.38 (6.57-10.30) (control: 6.71-7.95) and was 6.35 (6.28-6.50)(control: 6.29-6.31) in the non-irradiated cups.
Conclusions
Biphasic change was observed in both compression modulus and viscoelasticity in the irradiated cups. From SEM study, the biphasic change seems to come from the configuration change in the articulation surface, such as cracks and delamination on the articulation surface, after that the PE stiffened resulting from the oxidation.