title: Knee structural alteration and BMI: a cross-sectional study.
abstract: OBJECTIVE
  To describe the associations among BMI, knee cartilage morphology, and bone size in adults.
  
  
  METHODS
  A cross-sectional convenience sample of 372 male and female subjects (mean age, 45 years; range, 26 to 61 years) was studied. Knee articular cartilage defect score (0 to 4) and prevalence (defect score of >/=2), volume, and thickness, as well as bone surface area and/or volume, were determined at the patellar, tibial, and femoral sites using T1-weighted fat-saturation magnetic resonance imaging. Height, weight, BMI, and radiographic osteoarthritis were measured by standard protocols.
  
  
  RESULTS
  In multivariate analysis in the whole group, BMI was significantly associated with knee cartilage defect scores (beta: +0.016/kg/m(2) to +0.083/kg/m(2), all p < 0.05) and prevalence (odds ratio: 1.05 to 1.12/kg/m(2), all p < 0.05 except for the lateral tibiofemoral compartment). In addition, BMI was negatively associated with patellar cartilage thickness only (beta = -0.021 mm/kg/m(2); p = 0.039) and was positively associated with tibial bone area (medial: beta = +7.1 mm(2)/kg/m(2), p = 0.001; lateral: beta = +3.2 mm(2)/kg/m(2), p = 0.037). Those who were obese also had higher knee cartilage defect severity and prevalence and larger medial tibial bone area but no significant change in cartilage volume or thickness compared with those of normal weight.
  
  
  CONCLUSIONS
  This study suggests that knee cartilage defects and tibial bone enlargement are the main structural changes associated with increasing BMI particularly in women. Preventing these changes may prevent knee osteoarthritis in overweight and obese subjects.
authors.affiliation: Menzies Research Institute, University of Tasmania, Private Bag 23, Hobart, Tasmania 7000, Australia.
authors.forename: Changhai
authors.initials: C
authors.lastname: Ding
authors.forename: Flavia
authors.initials: F
authors.lastname: Cicuttini
authors.forename: Fiona
authors.initials: F
authors.lastname: Scott
authors.forename: Helen
authors.initials: H
authors.lastname: Cooley
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015992:Body Mass Index; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000473:pathology; D010003:Osteoarthritis / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D010329:Patella / Q000473:pathology; D012727:Sex Characteristics; D013977:Tibia / Q000473:pathology