title: Method for the location of primary wear scars from retrieved metal on metal hip replacements.
abstract: BACKGROUND
  Retrieved metal-on-metal acetabular cups are valuable resources in investigating the wear behaviour of failed hip implants, but adequate methods to do so are lacking. To further contribute to addressing this issue, we developed a method to detect the in vivo location of the primary wear scar of an explanted cup.
  
  
  METHODS
  We proposed a new method in which thirteen patients with failed metal hip resurfacings were recruited, and their acetabular components retrieved. A 3D wear map was generated and the precise location of the primary wear scar in each cup was identified using a coordinate measuring machine. This wear scar location was noted in relation to the features on the acetabular cup. Having identified the location of the wear scar, this 3D positional map was co-registered to the implant on the patient's pelvic 3D CT scan.
  
  
  RESULTS
  Using our proposed technique, we were able to demonstrate that the in vivo position of the primary wear scar in explanted metal acetabular cups can be variable.
  
  
  CONCLUSIONS
  This method has utilised existing techniques to better understand the three-dimensional properties of wear behaviour, and may be a method which can be used in further studies to investigate variables that affect the position of the primary wear scar.
authors.affiliation: University College London, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK. garima.govind.10@ucl.ac.uk.
authors.forename: Garima
authors.initials: G
authors.lastname: Govind
authors.affiliation: University College London, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK. johannhenckel@yahoo.co.uk.
authors.forename: Johann
authors.initials: J
authors.lastname: Henckel
authors.affiliation: University College London, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK. rejahho@ucl.ac.uk.
authors.forename: Harry
authors.initials: H
authors.lastname: Hothi
authors.affiliation: University College London, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK. shiraz.sabah@gmail.com.
authors.forename: Shiraz
authors.initials: S
authors.lastname: Sabah
authors.affiliation: University College London, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK. john.skinner@rnoh.nhs.uk.
authors.forename: John
authors.initials: J
authors.lastname: Skinner
authors.affiliation: University College London, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK. a.hart@ucl.ac.uk.
authors.forename: Alister
authors.initials: A
authors.lastname: Hart
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D019544:Equipment Failure Analysis / Q000379:methods*; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects / Q000592:standards*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design / Q000009:adverse effects / Q000592:standards*; D011475:Prosthesis Failure / Q000009:adverse effects