title: The hereditary predisposition to hip osteoarthritis and its association with abnormal joint morphology.
abstract: OBJECTIVE
  Genetic factors and abnormalities of joint morphology are important in the aetiology of hip osteoarthritis (OA). The extent to which genetic influences are manifest through joint morphology has undergone limited investigation. Using a cohort with an hereditary predisposition to end-stage hip OA and a control group with no inherited risk, we aimed to identify associations with abnormal joint morphology and clinical features.
  
  
  METHODS
  One hundred and twenty-three individuals (mean age 52 years) with a family history of total hip arthroplasty (THA) (termed 'sibkids') were compared with 80 spouse controls. Morphology was assessed using standardised radiographs and cam, dysplasia, and pincer deformities defined. Regression modelling described the association of cohort with abnormal joint morphology, adjusting for confounders [age, gender, body mass index (BMI), OA, and osteophyte].
  
  
  RESULTS
  Sibkids had an odds ratio of 2.1 [95%confidence interval (CI) 1.3-3.5] for cam deformity. There were no differences in the prevalence of dysplasia or pincer deformities. In both groups, hips with cam deformities or dysplasia were more likely to have clinical features than normal hips [odds ratio (OR) 4.46 (1.8-11.3), and 4.40 (1.4-14.3) respectively]. Pincer deformity was associated with positive signs in the sibkids but not in the controls (OR 3.0; 1.1-8.2).
  
  
  CONCLUSIONS
  After adjustment for confounders that cause secondary morphological change, individuals with an hereditary predisposition to end-stage hip OA had a higher prevalence of morphological abnormalities associated with hip OA. Sibkids were more likely to demonstrate clinical features in the presence of pincer deformity, suggesting that the genes are acting not only through abnormal morphology but also through other factors that influence the prevalence of pain.
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre NHS Trust, Headington, Oxford, United Kingdom. Tom.Pollard@ndorms.ox.ac.uk
authors.forename: T C B
authors.initials: TC
authors.lastname: Pollard
authors.forename: R N
authors.initials: RN
authors.lastname: Batra
authors.forename: A
authors.initials: A
authors.lastname: Judge
authors.forename: B
authors.initials: B
authors.lastname: Watkins
authors.forename: E G
authors.initials: EG
authors.lastname: McNally
authors.forename: H S
authors.initials: HS
authors.lastname: Gill
authors.forename: G E R
authors.initials: GE
authors.lastname: Thomas
authors.forename: S
authors.initials: S
authors.lastname: Glyn-Jones
authors.forename: N K
authors.initials: NK
authors.lastname: Arden
authors.forename: A J
authors.initials: AJ
authors.lastname: Carr
mesh_terms: D000077:Acetabulum / Q000002:abnormalities / Q000000981:diagnostic imaging; D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005269:Femur / Q000002:abnormalities / Q000000981:diagnostic imaging; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006621:Hip Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000453:epidemiology* / Q000235:genetics*; D011446:Prospective Studies; D011859:Radiography