title: Joint Stiffness Is Heritable and Associated with Fibrotic Conditions and Joint Replacement.
abstract: OBJECTIVE
  Joint stiffness is a common, debilitating, age-related symptom, which may be seen after total joint replacement (TJR). Stiffness also occurs in fibrotic conditions such as shoulder capsulitis and Dupuytren's contracture. We speculated that the two traits (TJR and fibrotic disease) are linked pathogenically.
  
  
  METHODS
  Using the TwinsUK NIHR BRC BioResource we tested the hypotheses that 1) joint (hip and knee) stiffness, TJR (hip and knee), and fibrotic conditions are associated and 2) genetic factors contribute to them.
  
  
  RESULTS
  Participating twins (n = 9718) had completed self-reported questionnaires on the traits of interest. All three traits were significantly associated with increasing age and body mass index (BMI), as well as female sex, on univariate analysis. Multivariable logistic regression analyses showed a significant association between TJR and joint stiffness (OR = 3.96, 95% confidence interval, CI 2.77-5.68) and between fibrotic conditions and joint stiffness (OR = 2.39, 1.74-3.29), adjusting for age, sex, BMI and twin relatedness. Monozygotic versus dizygotic intraclass correlations gave heritability estimates for TJR = 46% and joint stiffness = 32%.
  
  
  CONCLUSIONS
  That fibrotic conditions, joint stiffness and TJR are significantly associated suggests a common disease process, possibly fibrosis, which is genetically mediated.
authors.affiliation: Department of Twin Research & Genetic Epidemiology, King's College London, London United Kingdom.
authors.forename: Frances M
authors.initials: FM
authors.lastname: Williams
authors.affiliation: Department of Orthopaedics, The Royal Victoria Infirmary and the Freeman Hospital, Newcastle upon Tyne, United Kingdom; Fibrosis Research Group, Institute of Cellular Medicine, University of Newcastle, Newcasltle upon Tyne, United Kingdom.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Kalson
authors.affiliation: Department of Twin Research & Genetic Epidemiology, King's College London, London United Kingdom.
authors.forename: Stella M
authors.initials: SM
authors.lastname: Fabiane
authors.affiliation: Fibrosis Research Group, Institute of Cellular Medicine, University of Newcastle, Newcasltle upon Tyne, United Kingdom.
authors.forename: Derek A
authors.initials: DA
authors.lastname: Mann
authors.affiliation: Department of Orthopaedics, The Royal Victoria Infirmary and the Freeman Hospital, Newcastle upon Tyne, United Kingdom; Fibrosis Research Group, Institute of Cellular Medicine, University of Newcastle, Newcasltle upon Tyne, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Deehan
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D015992:Body Mass Index; D004387:Dupuytren Contracture / Q000503:physiopathology*; D005260:Female; D005355:Fibrosis / Q000503:physiopathology*; D020022:Genetic Predisposition to Disease; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015207:Osteoarthritis, Hip / Q000601:surgery; D020370:Osteoarthritis, Knee / Q000601:surgery; D016059:Range of Motion, Articular; D012307:Risk Factors; D011795:Surveys and Questionnaires; D006113:United Kingdom; D055815:Young Adult