title: A new method for shape and texture classification of orthopedic wear nanoparticles.
abstract: OBJECTIVE
  Detailed morphologic analysis of particles produced during wear of orthopedic implants is important in determining a correlation among material, wear, and biological effects. However, the use of simple shape descriptors is insufficient to categorize the data and to compare the nature of wear particles generated by different implants. An approach based on Discrete Fourier Transform (DFT) is presented for describing particle shape and surface texture.
  
  
  METHODS
  Four metal-on-metal bearing couples were tested in an orbital wear simulator under standard and adverse (steep-angled cups) wear simulator conditions. Digitized Scanning Electron Microscope (SEM) images of the wear particles were imported into MATLAB to carry out Fourier descriptor calculations via a specifically developed algorithm. The descriptors were then used for studying particle characteristics (shape and texture) as well as for cluster classification.
  
  
  CONCLUSIONS
  Analysis of the particles demonstrated the validity of the proposed model by showing that steep-angle Co-Cr wear particles were more asymmetric, compressed, extended, triangular, square, and roughened at 3 Mc than after 0.25 Mc. In contrast, particles from standard angle samples were only more compressed and extended after 3 Mc compared to 0.25 Mc. Cluster analysis revealed that the 0.25 Mc steep-angle particle distribution was a subset of the 3 Mc distribution.
authors.affiliation: The J. Vernon Luck, Sr., M.D. Orthopedic Research Center Los Angeles Orthopedic Hospital, Los Angeles, USA.
authors.forename: Dongning
authors.initials: D
authors.lastname: Zhang
authors.forename: Janet R
authors.initials: JR
authors.lastname: Page
authors.forename: Aaron E
authors.initials: AE
authors.lastname: Kavanaugh
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Billi
mesh_terms: D000465:Algorithms; D002857:Chromium / Q000737:chemistry; D016000:Cluster Analysis; D003035:Cobalt / Q000737:chemistry; D005583:Fourier Analysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry*; D019736:Prostheses and Implants
chemical_list: D002857:Chromium; D003035:Cobalt