title: The shape of the proximal femur influences acetabular wear patterns over time.
abstract: BACKGROUND
  Femoroacetabular impingement has been proposed as a cause of early osteoarthritis, but it is not known how this develops over time or whether the shape of the proximal femur influences this risk.
  
  
  OBJECTIVE
  (1) Which areas of the acetabulum are worn more frequently by individuals with a cam deformity of the proximal femur? (2) Do observed acetabular wear patterns differ based on the etiology of the cam deformity? (3) Do wear patterns of individuals with a cam deformity differ based on an individual's age?
  
  
  METHODS
  We examined 645 corresponding femora and acetabuli from the Hamann-Todd Osteological Collection and determined the offset and alpha angle using photographs; 370 specimens met inclusion criteria and were examined for signs of wear and the locations of wear were recorded. Specimens were separated into eight subgroups based on age either younger than 40 years or older than 60 years, alpha angle greater or less than 55°, and degree of anterior head-neck offset. We compared the prevalence of wear between groups in each location.
  
  
  RESULTS
  Individuals with abnormal geometry of the proximal femur demonstrated different wear patterns from individuals with normal geometry. There were few differences in wear patterns identified based on the etiology of the femoral deformity. Abnormal femoral geometry was associated with more frequent wear primarily at the anterosuperior acetabulum for individuals younger than 40 years of age and globally for individuals older than 60 years of age.
  
  
  CONCLUSIONS
  Femoral geometry appears to influence the pattern of acetabular wear occurring over time.
authors.affiliation: Orthopaedic Surgery, University Hospitals Case Medical Center, Cleveland, OH 44106, USA. jonathan.streit@gmail.com
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Streit
authors.forename: Ari
authors.initials: A
authors.lastname: Levine
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Barrett
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Cooperman
authors.forename: Victor
authors.initials: V
authors.lastname: Goldberg
mesh_terms: D000077:Acetabulum / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D057925:Femoracetabular Impingement / Q000473:pathology*; D005269:Femur / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged