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Analysis of a retrieved UHMWPE acetabular cup crosslinked in air with 1000 kGy of gamma radiation
Author(s) -
Sugano N.,
Saito M.,
Yamamoto T.,
Nishii T.,
Yau S. S.,
Wang A.
Publication year - 2004
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1016/j.orthres.2003.12.001
Subject(s) - ultimate tensile strength , materials science , polyethylene , crystallinity , irradiation , composite material , penetration (warfare) , nuclear chemistry , chemistry , physics , operations research , nuclear physics , engineering
The oxidation and degradation that accompany high dose gamma irradiation in air for crosslinking and sterilization are important because they could affect the clinical performance of polyethylene total joint implants. We report a clinical case of a 1000 kGy gamma‐irradiated, highly crosslinked ultra‐high molecular weight polyethylene acetabular cup retrieved 24 years postoperatively. Performance evaluations included absorbed radiation dose, total wear penetration, average wear rate, crystallinity, oxidation, and equibiaxial tensile properties. A retrieved acetabular cup of the same grade of polyethylene but gamma‐sterilized using a conventional dose was used as control. The highly crosslinked and control cups took in about 1300 and 30 kGy of radiation, respectively, as measured using a trans‐vinylene index. Direct dimensional measurements revealed average wear rates of the highly crosslinked and control cups were 0.04 and 0.06 mm/year, respectively. The oxidation index of the highly crosslinked cup was very high (0.679), but equivalent to that of a 1000 kGy irradiated reference cup. The retrieved highly crosslinked cup showed much higher equibiaxial ultimate tensile strength than the retrieved control cup. Based on these observations, the increased wear resistance and equibiaxial tensile properties that resulted from extensive crosslinking in the presence of air were partially offset by the adverse effects caused by immediate oxidation during the process. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.