Clinical Orthopaedics and Related Research®

, Volume 472, Issue 2, pp 624–629

Short-term Wear Evaluation of Thin Acetabular Liners on 36-mm Femoral Heads

  • Aaron J. Johnson
  • LaQuawn Loving
  • Lizeth Herrera
  • Ronald E. Delanois
  • Aiguo Wang
  • Michael A. Mont
Symposium: 2013 Hip Society Proceedings

DOI: 10.1007/s11999-013-3153-x

Cite this article as:
Johnson, A.J., Loving, L., Herrera, L. et al. Clin Orthop Relat Res (2014) 472: 624. doi:10.1007/s11999-013-3153-x

Abstract

Background

Dislocation remains the leading cause of revision THA. One approach to decreasing prosthetic dislocation risk has been the use of larger femoral head component sizes. The upper limit of head size in metal-on-polyethylene hip arthroplasty has historically been limited because of concerns about increased wear on thin polyethylene components. It is not known to what degree this concern should apply to more wear-resistant polyethylene components.

Questions/purposes

We therefore determined (1) in vitro wear rates of polyethylene liners of varying thicknesses, (2) whether there were differences in the microscopic wear characteristics as a function of polyethylene thickness, and (3) whether thin polyethylene components resulted in early catastrophic failures.

Methods

We used a hip wear simulator to compare the wear performance of 12 highly crosslinked polyethylene acetabular inserts. The internal diameter of all components was 36 mm, and there were three samples tested of each thickness (1.9, 3.9, 5.9, or 7.9 mm). Testing was conducted for 2.4 million cycles. Gravimetric mass loss was converted to volumetric loss, which was subsequently converted to theoretical linear penetration rates.

Results

Wear rates decreased with increasing polyethylene thickness. Mean ± SD wear rates for the 1.9-, 3.9-, 5.9-, and 7.9-mm groups were 5.0 ± 0.5, 3.2 ± 0.3, 2.5 ± 1.1, and 2.2 ± 1.3 mm3/million cycles, respectively (p < 0.016). Calculated penetration rates were 0.015, 0.012, 0.011, and 0.010 mm/million cycles, respectively (p < 0.016). There were no catastrophic failures in any group.

Conclusions

Thinner polyethylene components demonstrated higher wear rates, although even the highest wear rate observed in the thinnest polyethylene specimen was lower than that commonly reported for noncrosslinked polyethylene components. While encouraging, these findings should be validated in vivo before clinical recommendations can be made.

Copyright information

© The Association of Bone and Joint Surgeons® 2013

Authors and Affiliations

  • Aaron J. Johnson
    • 1
  • LaQuawn Loving
    • 2
  • Lizeth Herrera
    • 2
  • Ronald E. Delanois
    • 1
  • Aiguo Wang
    • 2
  • Michael A. Mont
    • 1
  1. 1.Center for Joint Preservation and ReconstructionRubin Institute for Advanced Orthopedics, Sinai Hospital of BaltimoreBaltimoreUSA
  2. 2.Stryker OrthopaedicsMahwahUSA