title: Prevalence of radiographic hip osteoarthritis is increased in high bone mass.
abstract: OBJECTIVE
  Epidemiological studies have shown an association between increased bone mineral density (BMD) and osteoarthritis (OA), but whether this represents cause or effect remains unclear. In this study, we used a novel approach to investigate this question, determining whether individuals with High Bone Mass (HBM) have a higher prevalence of radiographic hip OA compared with controls.
  
  
  METHODS
  HBM cases came from the UK-based HBM study: HBM was defined by BMD Z-score. Unaffected relatives of index cases were recruited as family controls. Age-stratified random sampling was used to select further population controls from the Chingford and Hertfordshire cohort studies. Pelvic radiographs were pooled and assessed by a single observer blinded to case-control status. Analyses used logistic regression, adjusted for age, gender and body mass index (BMI).
  
  
  RESULTS
  530 HBM hips in 272 cases (mean age 62.9 years, 74% female) and 1702 control hips in 863 controls (mean age 64.8 years, 84% female) were analysed. The prevalence of radiographic OA, defined as Croft score ≥3, was higher in cases compared with controls (20.0% vs 13.6%), with adjusted odds ratio (OR) [95% CI] 1.52 [1.09, 2.11], P = 0.013. Osteophytes (OR 2.12 [1.61, 2.79], P < 0.001) and subchondral sclerosis (OR 2.78 [1.49, 5.18], P = 0.001) were more prevalent in cases. However, no difference in the prevalence of joint space narrowing (JSN) was seen (OR 0.97 [0.72, 1.33], P = 0.869).
  
  
  CONCLUSIONS
  An increased prevalence of radiographic hip OA and osteophytosis was observed in HBM cases compared with controls, in keeping with a positive association between HBM and OA and suggesting that OA in HBM has a hypertrophic phenotype.
authors: Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, UK; MRC Integrative Epidemiology Unit, University of Bristol, UK. Electronic address: Sarah.Hardcastle@bristol.ac.uk.
authors: S A
authors: SA
authors: Hardcastle
authors: Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, UK; University of Exeter Medical School, Exeter, UK.
authors: P
authors: P
authors: Dieppe
authors: Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, UK.
authors: C L
authors: CL
authors: Gregson
authors: Oxford NIHR Musculoskeletal Biomedical Research Unit, University of Oxford, Oxford, UK; Chromatic Innovation Limited, 23 Chesham St, Leamington Spa, CV31 1JS, UK.
authors: D
authors: D
authors: Hunter
authors: Oxford NIHR Musculoskeletal Biomedical Research Unit, University of Oxford, Oxford, UK.
authors: G E R
authors: GE
authors: Thomas
authors: Oxford NIHR Musculoskeletal Biomedical Research Unit, University of Oxford, Oxford, UK; MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK; Arthritis Research UK (ARUK) Centre for Sports, Exercise and Osteoarthritis, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK.
authors: N K
authors: NK
authors: Arden
authors: Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.
authors: T D
authors: TD
authors: Spector
authors: Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.
authors: D J
authors: DJ
authors: Hart
authors: Department of Radiology, Royal United Hospital Bath NHS Trust, Bath, UK.
authors: M J
authors: MJ
authors: Laugharne
authors: Department of Radiology, Royal Glamorgan Hospital, Cwm Taf Health Board, Llantrisant, Wales, UK.
authors: G A
authors: GA
authors: Clague
authors: MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK.
authors: M H
authors: MH
authors: Edwards
authors: MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK.
authors: E M
authors: EM
authors: Dennison
authors: Oxford NIHR Musculoskeletal Biomedical Research Unit, University of Oxford, Oxford, UK; MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK; NIHR Nutrition Biomedical Research Centre, University of Southampton, Southampton, UK.
authors: C
authors: C
authors: Cooper
authors: Department of Radiology, North Bristol NHS Trust, Bristol, UK.
authors: M
authors: M
authors: Williams
authors: MRC Integrative Epidemiology Unit, University of Bristol, UK.
authors: G
authors: G
authors: Davey Smith
authors: Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, UK.
authors: J H
authors: JH
authors: Tobias
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging / Q000453:epidemiology*; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000453:epidemiology*; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015995:Prevalence; D006113:United Kingdom / Q000453:epidemiology
keywords: DXA; Epidemiology; Osteoarthritis; Osteoporosis; Radiology