Clinical Orthopaedics and Related Research®

, Volume 470, Issue 2, pp 462–470

The Effect of Poly Sterilization on Wear, Osteolysis and Survivorship of a Press-fit Cup at 10-Year Followup

  • Charles A. Engh
  • Cara C. Powers
  • Henry Ho
  • Sarah E. Beykirch-Padgett
  • Robert H. HopperJr
  • C. Anderson EnghJr
Symposium: Papers Presented at the Annual Meetings of The Hip Society

DOI: 10.1007/s11999-011-2052-2

Cite this article as:
Engh, C.A., Powers, C.C., Ho, H. et al. Clin Orthop Relat Res (2012) 470: 462. doi:10.1007/s11999-011-2052-2

Abstract

Background

During the mid-1990s when our institution was using a press-fit porous-coated cup without supplemental initial fixation for primary THA, the manufacturer transitioned from gamma irradiation to gas plasma for the terminal sterilization of their polyethylene liners.

Questions/purposes

At minimum 10-year followup, we asked whether the fixation achieved by solely relying on a press-fit would be durable and how different liner sterilization methods affected radiographic wear, osteolysis, and survivorship.

Patients and Methods

We retrospectively reviewed 373 patients who underwent 398 primary THAs with a press-fit porous-coated cup between March 1995 and December 1996. Mean age at time of surgery was 61.5 ± 13.3 years and mean followup was 10.4 ± 3.7 years. We determined reasons for revision, survivorship, femoral head penetration, osteolysis, and wear-related complications.

Results

Among 20 revisions involving any component, seven were associated with wear and osteolysis. Kaplan-Meier survivorship, using component revision for any reason as an end point, was 95.7% (95% confidence interval, 93.6%–97.9%) at 10 years. Noncrosslinked liners sterilized with gas plasma demonstrated a mean head penetration rate of 0.20 ± 0.09 mm/year compared with 0.13 ± 0.07 mm/year for liners sterilized with gamma irradiation in air and 0.09 ± 0.04 mm/year for liners sterilized with gamma-irradiation with barrier packaging without oxygen. THAs with increased volumetric wear tended to demonstrate larger osteolytic lesions (r = 0.40) and there tended to be less osteolysis among the liners sterilized with gamma-irradiation with barrier packaging without oxygen. However, there was no difference in survivorship among the sterilization groups and there has been no cup or stem loosening associated with osteolysis.

Conclusions

Durable biologic fixation through 10-year followup can be achieved by solely relying on an initial press-fit. Noncrosslinking gas plasma for terminal sterilization of the polyethylene liners was associated with greater head penetration rate than gamma irradiation.

Level of Evidence

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Copyright information

© The Association of Bone and Joint Surgeons® 2011

Authors and Affiliations

  • Charles A. Engh
    • 1
    • 2
  • Cara C. Powers
    • 1
  • Henry Ho
    • 1
  • Sarah E. Beykirch-Padgett
    • 1
  • Robert H. HopperJr
    • 1
  • C. Anderson EnghJr
    • 1
    • 2
  1. 1.Anderson Orthopaedic Research InstituteAlexandriaUSA
  2. 2.Inova Center for Joint Replacement at Mount Vernon HospitalAlexandriaUSA

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