title: Subclinical deformities of the hip are significant predictors of radiographic osteoarthritis and joint replacement in women. A 20 year longitudinal cohort study.
abstract: OBJECTIVE
  Femoroacetabular Impingement (FAI) and Acetabular Dysplasia are common deformities, which have been implicated as a major cause of hip osteoarthritis (OA). We examined whether these subtle deformities of the hip are associated with the development of radiographic OA and total hip replacement (THR) in women.
  
  
  METHODS
  A population-based, longitudinal cohort of 1003 women underwent pelvis radiographs at years 2 and 20. Alpha Angle, Triangular Index Height, Lateral Centre Edge (LCE) angle and Extrusion Index were measured. An alpha angle of greater than 65° was defined as Cam-type FAI. Radiographic OA and the presence of a THR were then determined at 20 years.
  
  
  RESULTS
  Cam-type FAI was significantly associated with the development of radiographic OA. Each degree increase in alpha angle above 65° was associated with an increase in risk of 5% (Odds Ratio (OR) 1.05 [95% confidence interval (CI) 1.01-1.09]) for radiographic OA and 4% (OR 1.04 [95% CI 1.00-1.08]) for THR. For Acetabular Dysplasia, each degree reduction in LCE angle below 28° was associated with an increase in risk of 13.0% (OR 0.87 [95% CI 0.78-0.96]) for radiographic OA and 18% (OR 0.82 [95% CI 0.75-0.89]) for THR.
  
  
  CONCLUSIONS
  This study demonstrates that Cam-type FAI and mild Acetabular Dysplasia are predictive of subsequent OA and THR in a large female population cohort. These are independent of age, BMI and joint space and significantly improve current predictive models of hip OA development.
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK. Electronic address: geraint.thomas@ndorms.ox.ac.uk.
authors.forename: G E R
authors.initials: GE
authors.lastname: Thomas
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: A J R
authors.initials: AJ
authors.lastname: Palmer
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: R N
authors.initials: RN
authors.lastname: Batra
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: A
authors.initials: A
authors.lastname: Kiran
authors.affiliation: Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital Campus, 3rd & 4th Floor South Wing Block D, Westminster Bridge Road, London SE1 7EH, UK.
authors.forename: D
authors.initials: D
authors.lastname: Hart
authors.affiliation: Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital Campus, 3rd & 4th Floor South Wing Block D, Westminster Bridge Road, London SE1 7EH, UK.
authors.forename: T
authors.initials: T
authors.lastname: Spector
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: M K
authors.initials: MK
authors.lastname: Javaid
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: A
authors.initials: A
authors.lastname: Judge
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: D W
authors.initials: DW
authors.lastname: Murray
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Carr
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK; MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK.
authors.forename: N K
authors.initials: NK
authors.lastname: Arden
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford OX3 7LD, UK.
authors.forename: S
authors.initials: S
authors.lastname: Glyn-Jones
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D058070:Asymptomatic Diseases; D015331:Cohort Studies; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006621:Hip Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000601:surgery; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors
keywords: Acetabular dysplasia; Epidemiology; Femoroacetabular impingement; Hip osteoarthritis; Osteoarthritis