title: In vitro wear assessment of the Charité Artificial Disc according to ASTM recommendations.
abstract: METHODS
  Biomechanical laboratory research.
  
  
  OBJECTIVE
  To evaluate the potential for Ultra High Molecular Weight Polyethylene (UHMWPE) wear debris from the Charité Artificial Disc.
  
  
  BACKGROUND
  Cases of osteolysis from artificial discs are extremely rare, but hip and knee studies demonstrate the osteolytic potential and clinical concern of UHMWPE wear debris. Standards for testing artificial discs continue to evolve, and there are few detailed reports of artificial disc wear characterizations.
  
  
  METHODS
  Implant assemblies were tested to 10 million cycles of +/- 7.5 degrees flexion-extension or +/- 7.5 degrees left/right lateral bending, both with +/- 2 degrees axial rotation and 900 N to 1,850 N cyclic compression. Cores were weighed, measured, and photographed. Soak and loaded soak controls were used. Wear debris was analyzed via scanning electron microscopy and particle counters.
  
  
  RESULTS
  The average total wear of the implants was 0.11 and 0.13 mg per million cycles, before and after accounting for serum absorption, respectively. Total height loss was approximately 0.2 mm. Wear debris ranged from submicron to > 10 microm in size.
  
  
  CONCLUSIONS
  Under these test conditions, the Charité Artificial Disc produced minimal wear debris. Debris size and morphology tended to be similar to other CoCr-UHMWPE joints. More testing is necessary to evaluate the implants under a spectrum of loading conditions.
authors.affiliation: DePuy Spine, Johnson & Johnson, Raynham, MA 02767, USA. hserhan@dpyus.jnj.com
authors.forename: Hassan A
authors.initials: HA
authors.lastname: Serhan
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Dooris
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Parsons
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Ares
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Gabriel
mesh_terms: D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D007403:Intervertebral Disc; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011095:Polyethylenes / Q000009:adverse effects; D019736:Prostheses and Implants / Q000009:adverse effects
chemical_list: D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene