title: The John Charnley Award: an accurate and sensitive method to separate, display, and characterize wear debris: part 1: polyethylene particles.
abstract: BACKGROUND
  Numerous studies indicate highly crosslinked polyethylenes reduce the wear debris volume generated by hip arthroplasty acetabular liners. This, in turns, requires new methods to isolate and characterize them.
  
  
  OBJECTIVE
  We describe a method for extracting polyethylene wear particles from bovine serum typically used in wear tests and for characterizing their size, distribution, and morphology.
  
  
  METHODS
  Serum proteins were completely digested using an optimized enzymatic digestion method that prevented the loss of the smallest particles and minimized their clumping. Density-gradient ultracentrifugation was designed to remove contaminants and recover the particles without filtration, depositing them directly onto a silicon wafer. This provided uniform distribution of the particles and high contrast against the background, facilitating accurate, automated, morphometric image analysis. The accuracy and precision of the new protocol were assessed by recovering and characterizing particles from wear tests of three types of polyethylene acetabular cups (no crosslinking and 5 Mrads and 7.5 Mrads of gamma irradiation crosslinking).
  
  
  RESULTS
  The new method demonstrated important differences in the particle size distributions and morphologic parameters among the three types of polyethylene that could not be detected using prior isolation methods.
  
  
  CONCLUSIONS
  The new protocol overcomes a number of limitations, such as loss of nanometer-sized particles and artifactual clumping, among others.
  
  
  CONCLUSIONS
  The analysis of polyethylene wear particles produced in joint simulator wear tests of prosthetic joints is a key tool to identify the wear mechanisms that produce the particles and predict and evaluate their effects on periprosthetic tissues.
authors: The J. Vernon Luck Sr., MD, Orthopaedic Research Center at Orthopaedic Hospital, UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery, David Geffen School of Medicine, Los Angeles, CA 90007, USA. fbilli@laoh.ucla.edu
authors: Fabrizio
authors: F
authors: Billi
authors: Paul
authors: P
authors: Benya
authors: Aaron
authors: A
authors: Kavanaugh
authors: John
authors: J
authors: Adams
authors: Edward
authors: E
authors: Ebramzadeh
authors: Harry
authors: H
authors: McKellop
mesh_terms: D000818:Animals; D001363:Awards and Prizes; D001798:Blood Proteins / Q000737:chemistry; D002417:Cattle; D002499:Centrifugation, Density Gradient; D002623:Chemistry Techniques, Analytical; D005720:Gamma Rays; D006622:Hip Prosthesis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D020959:Polyethylene / Q000032:analysis / Q000737:chemistry* / Q000528:radiation effects; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012828:Silicones / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical
chemical_list: D001798:Blood Proteins; D012828:Silicones; D020959:Polyethylene