title: In vitro quantification of wear in tibial inserts using microcomputed tomography.
abstract: BACKGROUND
  Wear of polyethylene tibial inserts can decrease the longevity of total knee arthroplasty. Wear is currently assessed using laboratory methods that may not permit backside wear measurements or do not quantify surface deviation.
  
  
  OBJECTIVE
  We developed and validated a technique to quantify polyethylene wear in tibial inserts using microcomputed tomography (micro-CT), a nondestructive high-resolution imaging technique that provides detailed images of surface geometry in addition to volumetric measurements.
  
  
  METHODS
  Six unworn and six wear-simulated polyethylene tibial inserts were evaluated. Each insert was scanned three times using micro-CT at a resolution of 50 μm. The insert surface was reconstructed for each scan and the insert volume was calculated. Gravimetric analysis was performed for all inserts, and the micro-CT and gravimetric volumes were compared to determine accuracy. We created three-dimensional surface deviation maps.
  
  
  RESULTS
  Micro-CT generated high-quality three-dimensional renderings of the insert surface geometry. Between-scan precision was 0.07%; we observed no difference between micro-CT and gravimetric volume measurements.
  
  
  CONCLUSIONS
  Micro-CT can provide precise and accurate volumetric measurements in addition to quantifiable three-dimensional surface deviation maps for the entire insert surface. The technique has the potential to evaluate wear in wear simulator trials and retrieval studies.
  
  
  CONCLUSIONS
  This micro-CT technique combines the benefits of volumetric and surface scanning methods to quantify wear across all surfaces of polyethylene components with a single tool. When applied in wear simulator and retrieval studies, these measurements can be used to evaluate and predict the wear properties of the components.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, PO Box 5015, London, ON N6A 5K8, Canada. mteeter@imaging.robarts.ca
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Teeter
authors.forename: Douglas D R
authors.initials: DD
authors.lastname: Naudie
authors.forename: David D
authors.initials: DD
authors.lastname: McErlain
authors.forename: Jan-M
authors.initials: JM
authors.lastname: Brandt
authors.forename: Xunhua
authors.initials: X
authors.lastname: Yuan
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Macdonald
authors.forename: David W
authors.initials: DW
authors.lastname: Holdsworth
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation*; D005240:Feasibility Studies; D021621:Imaging, Three-Dimensional; D007720:Knee Prosthesis; D008422:Materials Testing; D010865:Pilot Projects; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013499:Surface Properties; D055114:X-Ray Microtomography
chemical_list: D020959:Polyethylene