title: Long-term evaluation of a compliant cushion form acetabular bearing for hip joint replacement: a 20 million cycles wear simulation.
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.
authors.affiliation: Research & Development Center, Active Implants Corporation, Netanya 42505, Israel. jon.elsner@activeimplants.com
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Elsner
authors.forename: Maoz
authors.initials: M
authors.lastname: Shemesh
authors.forename: Yoav
authors.initials: Y
authors.lastname: Mezape
authors.forename: Mario
authors.initials: M
authors.lastname: Levenshtein
authors.forename: Keren
authors.initials: K
authors.lastname: Hakshur
authors.forename: Avi
authors.initials: A
authors.lastname: Shterling
authors.forename: Eran
authors.initials: E
authors.lastname: Linder-Ganz
authors.forename: Noam
authors.initials: N
authors.lastname: Eliaz
mesh_terms: D000077:Acetabulum / Q000502:physiology* / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002858:Chromium Alloys; D004548:Elasticity / Q000502:physiology; D019544:Equipment Failure Analysis / Q000379:methods*; D005270:Femur Head / Q000502:physiology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D008953:Models, Anatomic; D011076:Polycarboxylate Cement; D013997:Time Factors; D014520:Urethane; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D002858:Chromium Alloys; D011076:Polycarboxylate Cement; C005506:polycarbonate; D014520:Urethane