title: Wear of the Charité® lumbar intervertebral disc replacement investigated using an electro-mechanical spine simulator.
abstract: The Charité(®) lumbar intervertebral disc replacement was subjected to wear testing in an electro-mechanical spine simulator. Sinusoidally varying compression (0.6-2 kN, frequency 2 Hz), rotation (±2°, frequency 1 Hz), flexion-extension (6° to -3°, frequency 1 Hz) and lateral bending (±2°, frequency 1 Hz) were applied out of phase to specimens immersed in diluted calf serum at 37 °C. The mass of the ultra-high-molecular weight polyethylene component of the device was measured at intervals of 0.5, 1, 2, 3, 4 and 5 million cycles; its volume was also measured by micro-computed tomography. Total mass and volume losses were 60.3 ± 4.6 mg (mean ± standard deviation) and 64.6 ± 6.0 mm(3). Corresponding wear rates were 12.0 ± 1.4 mg per million cycles and 12.8 ± 1.2 mm(3) per million cycles; the rate of loss of volume corresponds to a mass loss of 11.9 ± 1.1 mg per million cycles, that is, the two sets of measurements of wear agree closely. Wear rates also agree closely with measurements made in another laboratory using the same protocol but using a conventional mechanical spine simulator.
authors.affiliation: School of Mechanical Engineering, University of Birmingham, Birmingham, UK.
authors.forename: Parshia
authors.initials: P
authors.lastname: Moghadas
authors.affiliation: School of Mechanical Engineering, University of Birmingham, Birmingham, UK a.mahomed@bham.ac.uk.
authors.forename: Aziza
authors.initials: A
authors.lastname: Mahomed
authors.affiliation: School of Mechanical Engineering, University of Birmingham, Birmingham, UK.
authors.forename: Duncan E T
authors.initials: DE
authors.lastname: Shepherd
authors.affiliation: School of Mechanical Engineering, University of Birmingham, Birmingham, UK.
authors.forename: David W L
authors.initials: DW
authors.lastname: Hukins
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D006801:Humans; D007403:Intervertebral Disc / Q000502:physiology*; D008159:Lumbar Vertebrae / Q000502:physiology*; D008422:Materials Testing / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D011095:Polyethylenes / Q000737:chemistry; D011474:Prosthesis Design; D059145:Total Disc Replacement / Q000295:instrumentation*
chemical_list: D001672:Biocompatible Materials; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene
keywords: Intervertebral disc replacement; spine simulators; ultra-high-molecular weight polyethylene; wear rates
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