title: Vastus medialis fat infiltration - a modifiable determinant of knee cartilage loss.
abstract: BACKGROUND
  There is growing interest in the role of intramuscular fat and how it may influence clinical outcomes. Vastus medialis (VM) is a functionally important quadriceps muscle that helps to stabilise the knee joint. This longitudinal study examined the determinants of VM fat infiltration and whether VM fat infiltration influenced knee cartilage volume.
  
  
  METHODS
  250 participants without any diagnosed arthropathy were assessed at baseline between 2005 and 2008, and 197 participants at follow-up between 2008 and 2010. Ambulatory and sporting activity were assessed and magnetic resonance imaging (MRI) was used to determine knee cartilage volume and VM fat infiltration.
  
  
  RESULTS
  Age, female gender, BMI and weight were positively associated with baseline VM fat infiltration (P ≤ 0.03), while ambulatory and sporting activity were negatively associated with VM fat infiltration (P ≤ 0.05). After adjusting for confounders, a reduction in VM fat infiltration was associated with a reduced annual loss of medial tibial (β = -10 mm(3); 95% CI -19 to 0 mm(3); P = 0.04) and patella (β = -18 mm(3); 95% CI -36 to 0 mm(3); P = 0.04) cartilage volume.
  
  
  CONCLUSIONS
  This community-based study of healthy adults has shown that VM fat infiltration can be modified by lifestyle factors including weight loss and exercise, and reducing fat infiltration in VM has beneficial effect on knee cartilage preservation. The findings suggest that modifying VM fat infiltration via lifestyle interventions may have the potential to reduce the risk of knee OA.
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia; Baker IDI Heart and Diabetes Institute, Commercial Road, Melbourne, VIC 3004, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Teichtahl
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia.
authors.forename: A E
authors.initials: AE
authors.lastname: Wluka
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia.
authors.forename: P N
authors.initials: PN
authors.lastname: Wijethilake
authors.affiliation: Department of Medicine, Monash University, Melbourne, VIC 3168, Australia.
authors.forename: B J
authors.initials: BJ
authors.lastname: Strauss
authors.affiliation: University of Melbourne, Department of Medicine, Austin Hospital, Melbourne, VIC 3084, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Proietto
authors.affiliation: Baker IDI Heart and Diabetes Institute, Commercial Road, Melbourne, VIC 3004, Australia.
authors.forename: J B
authors.initials: JB
authors.lastname: Dixon
authors.affiliation: Menzies Research Institute, Private Bag 23, Hobart, TAS 7000, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Jones
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Forbes
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia.
authors.forename: F M
authors.initials: FM
authors.lastname: Cicuttini
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D001835:Body Weight; D002358:Cartilage, Articular / Q000473:pathology*; D015444:Exercise; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008019:Life Style; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D052097:Quadriceps Muscle / Q000473:pathology*; D012737:Sex Factors; D013177:Sports; D016138:Walking
keywords: Exercise; Fat; Knee; Muscle; Obesity