Retrieval analysis of Harris-Galante I and II acetabular liners in situ for more than 10 years

Abstract

Background and purpose There have been few reports documenting the wear and oxidation performance of the polyethylene bearing surface of HGPI and HGPII THA devices.

We evaluated retrieved HGPI and HGPII acetabular liners that had been in situ for more than 10 years and determined whether there was a relationship between clinical and radiographic factors, surface damage, wear, and oxidation.

Materials and methods 129 HGPI and II acetabular liners with implantation times of > 10 years were retrieved at 4 institutions between 1997 and 2010. The liners were made from a single resin and were gamma radiation-sterilized in air. Surface damage, linear wear, and oxidation index (OI) were assessed. Differences in clinical and radiographic factors, surface damage, linear wear, and OI for the 2 designs were statistically evaluated separately and together.

Results Articular surface damage and backside damage was similar in the 2 designs. The linear penetration rate was 0.14 (SD 0.07) mm/year for the HGPI liners and 0.12 (SD 0.08) mm/year for the HGPII liners. For both cohorts, the rim had a higher OI than the articular surface. 74% of the liners had subsurface cracking and 24% had a complete fracture through the acetabular rim.

Interpretation Despite modification of the HGP locking mechanism in the HGPII design, dissociation of the liner from the acetabular shell can still occur if fracture of the rim of the liner develops due to oxidative degradation.

KF gathered and analyzed implant damage and wear data and contributed text to the manuscript; RM gathered and analyzed implant damage and wear data, performed statistical analyses, and contributed text to the manuscript; HG gathered and analyzed FTIR data, performed statistical analyses, and contributed text to the manuscript; SK designed the study and analyzed and interpreted data; MK and VG operated on and followed patients, designed the study, analyzed and interpreted data, and contributed text to the manuscript; KX gathered radiographic data; CR designed the study, analyzed and interpreted data, and contributed text to the manuscript.

We thank Dan MacDonald of the Implant Research Center at Drexel University for assisting in the FTIR analysis and statistics.

The institutions of the authors have received funding from the National Institutes of Health (NIAMS) R01 AR47904 (CWRU and Drexel) and through the Wilbert J. Austin Professor of Engineering Chair (CMR) and the Saint Luke Foundation: Timothy L. Stephen’s Jr. Fellowship Grant (KF).