Long-term evaluation of a compliant cushion form acetabular bearing for hip joint replacement: a 20 million cycles wear simulation

J Orthop Res. 2011 Dec;29(12):1859-66. doi: 10.1002/jor.21471. Epub 2011 May 31.

Abstract

Soft bearing materials that aim to reproduce the tribological function of the natural joint are gaining popularity as an alternative concept to conventional hard bearing materials in the hip and knee. However, it has not been proven so far that an elastic cushion bearing can be sufficiently durable as a long term (∼20 years) articulating joint prosthesis. The use of new bearing materials should be supported by accurate descriptions of the implant following usage and of the number, volume, and type of wear particles generated. We report on a long-term 20 million cycle (Mc) wear study of a commercial hip replacement system composed of a compliant polycarbonate-urethane (PCU) acetabular liner coupled to a cobalt-chromium alloy femoral head. The PCU liner showed excellent wear characteristics in terms of its low and steady volumetric wear rate (5.8-7.7 mm(3)/Mc) and low particle generation rate (2-3 × 10(6) particles/Mc). The latter is 5-6 orders of magnitude lower than that of highly cross-linked polyethylene and 6-8 orders of magnitude lower than that of metal-on-metal bearings. Microscopic analysis of the implants after the simulation demonstrated a low damage level to the implants' articulating surfaces. Thus, the compliant PCU bearing may provide a substantial advantage over traditional bearing materials.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetabulum / physiology*
  • Acetabulum / surgery*
  • Arthroplasty, Replacement, Hip / instrumentation*
  • Chromium Alloys
  • Elasticity / physiology
  • Equipment Failure Analysis / methods*
  • Femur Head / physiology
  • Femur Head / surgery
  • Hip Prosthesis*
  • Humans
  • Materials Testing / methods*
  • Models, Anatomic
  • Polycarboxylate Cement
  • Time Factors
  • Urethane
  • Weight-Bearing / physiology

Substances

  • Chromium Alloys
  • Polycarboxylate Cement
  • polycarbonate
  • Urethane