title: Changes in bone marrow lesions in response to weight-loss in obese knee osteoarthritis patients: a prospective cohort study.
abstract: BACKGROUND
  Patients are susceptible for knee osteoarthritis (KOA) with increasing age and obesity and KOA is expected to become a major disabling disease in the future. An important feature of KOA on magnetic resonance imaging (MRI) is changes in the subchondral bone, bone marrow lesions (BMLs), which are related to the future degeneration of the knee joint as well as prevalent clinical symptoms. The aim of this study was to investigate the changes in BMLs after a 16-week weight-loss period in obese subjects with KOA and relate changes in BMLs to the effects of weight-loss on clinical symptoms.
  
  
  METHODS
  This prospective cohort study included patients with a body mass index ≥ 30 kg/m2, an age ≥ 50 years and primary KOA. Patients underwent a 16 weeks supervised diet program which included formula products and dietetic counselling (ClinicalTrials.gov: NCT00655941). BMLs in tibia and femur were assessed on MRI before and after the weight-loss using the Boston-Leeds Osteoarthritis Knee Score. Response to weight-loss in BML scores was dichotomised to patients experiencing a decrease in BML scores (responders) and patients who did not (non-responders). The association of BMLs to weight-loss was assessed by logistic regressions and correlation analyses.
  
  
  RESULTS
  39 patients (23%) were classified as responders in the sum of all BML size scores whereas 130 patients (77%) deteriorated or remained stable and were categorized as non-responders. Logistic regression analyses revealed no association between weight-loss < or ≥ 10% and response in BMLs in the most affected compartment (OR 1.86 [CI 0.66 to 5.26, p=0.24]). There was no association between weight-loss and response in maximum BML score (OR 1.13 [CI 0.39 to 3.28, p=0.81]). The relationship between changes in BMLs and clinical symptoms revealed that an equal proportion of patients classified as BML responders and non-responders experienced an OMERACT-OARSI response (69 vs. 71%, p=0.86).
  
  
  CONCLUSIONS
  Weight-loss did not improve the sum of tibiofemoral BML size scores or the maximum tibiofemoral BML score, suggesting that BMLs do not respond to a rapidly decreased body weight. The missing relationship between clinical symptoms and BMLs calls for further investigation.
authors.affiliation: The Parker Institute, Department of Rheumatology, Copenhagen University Hospital, Frederiksberg, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Gudbergsen
authors.forename: Mikael
authors.initials: M
authors.lastname: Boesen
authors.forename: Robin
authors.initials: R
authors.lastname: Christensen
authors.forename: Else Marie
authors.initials: EM
authors.lastname: Bartels
authors.forename: Marius
authors.initials: M
authors.lastname: Henriksen
authors.forename: Bente
authors.initials: B
authors.lastname: Danneskiold-Samsøe
authors.forename: Henning
authors.initials: H
authors.lastname: Bliddal
mesh_terms: D000368:Aged; D001853:Bone Marrow / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000628:therapy*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000628:therapy*; D011446:Prospective Studies; D011859:Radiography; D015431:Weight Loss / Q000502:physiology