title: Smoking is associated with increased cartilage loss and persistence of bone marrow lesions over 2 years in community-based individuals.
abstract: OBJECTIVE
  To determine whether smoking is related to change in tibial and patella cartilage, and the development or persistence of bone marrow lesions (BMLs) over 2 years in a cohort of middle-aged adults.
  
  
  METHODS
  Two hundred and seventy-one adult subjects recruited from the Melbourne Collaborative Cohort Study underwent an MRI of their dominant knee at baseline and approximately 2 years later. Cartilage volume and BMLs were determined for both time points. At baseline, subjects also completed a questionnaire about current and past cigarette smoking.
  
  
  RESULTS
  Being a 'smoker' (former or current) was associated with increased annual loss of medial but not lateral or patella cartilage volume (medial: difference = 13.4 microl, P = 0.03; lateral difference = 4.86 microl, P = 0.45, patella difference = -2.57 microl, P = 0.79). A relationship between increasing pack-years smoked and increased medial cartilage volume loss was also observed (P = 0.04). Amongst people who had a BML at baseline, BMLs present in 'ever smokers' were 11.4 [95% confidence interval (CI) 1.54, 89.9; P = 0.02] times more likely to persist over 2 years than those present in 'never smokers'. In addition, the relationship between smoking and increased medial cartilage loss for subjects with a BML present at baseline was partially mediated by the persistence of the BMLs over 2 years.
  
  
  CONCLUSIONS
  This study contributes to the evidence of a detrimental effect of smoking on joint cartilage. Furthermore, it provides a possible mechanism that the association smoking shares with increased cartilage loss may be mediated via smoking impairing the ability for BMLs to resolve.
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Central and Eastern Clinical School, Alfred Hospital, Melbourne, Victoria 3004, Australia.
authors.forename: Miranda L
authors.initials: ML
authors.lastname: Davies-Tuck
authors.forename: Anita E
authors.initials: AE
authors.lastname: Wluka
authors.forename: Andrew
authors.initials: A
authors.lastname: Forbes
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.forename: Dallas R
authors.initials: DR
authors.lastname: English
authors.forename: Graham G
authors.initials: GG
authors.lastname: Giles
authors.forename: Flavia
authors.initials: F
authors.lastname: Cicuttini
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry / Q000379:methods; D001855:Bone Marrow Diseases / Q000209:etiology* / Q000473:pathology; D002358:Cartilage, Articular / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000473:pathology*; D012907:Smoking / Q000009:adverse effects*