title: Quadriceps volumes are reduced in people with patellofemoral joint osteoarthritis.
abstract: OBJECTIVE
  This study aimed to (1) compare the volumes of vastus medialis (VM), vastus lateralis (VL), vastus intermedius and rectus femoris and the ratio of VM/VL volumes between asymptomatic controls and patellofemoral joint osteoarthritis (PFJ OA) participants; and (2) assess the relationships between cross-sectional area (CSA) and volumes of the VM and VL in individuals with and without PFJ OA.
  
  
  METHODS
  Twenty-two participants with PFJ OA and 11 controls aged ≥ 40 years were recruited from the community and practitioner referrals. Muscle volumes of individual quadriceps components were measured from thigh magnetic resonance (MR) images. The CSA of the VM and lateralis were measured at 10 equally distributed levels (femoral condyles to lesser femoral trochanter).
  
  
  RESULTS
  PFJ OA individuals had smaller normalized VM (mean difference 0.90 cm(3) · kg(-1), α = 0.011), VL (1.50 cm(3) · kg(-1), α = 0.012) and rectus femoris (0.71 cm(3) · kg(-1), α = 0.009) volumes than controls. No differences in the VM/VL ratio were observed. The CSA at the third level (controls) and fourth level (PFJ OA) above the femoral condyles best predicted VM volume, whereas the VL volume was best predicted by the CSA at the seventh level (controls) and sixth level (PFJ OA) above the femoral condyles.
  
  
  CONCLUSIONS
  Reduced quadriceps muscle volume was a feature of PFJ OA. Muscle volume could be predicted from CSA measurements at specific levels in PFJ OA patients and controls.
authors.affiliation: Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: H F
authors.initials: HF
authors.lastname: Hart
authors.forename: D C
authors.initials: DC
authors.lastname: Ackland
authors.forename: M G
authors.initials: MG
authors.lastname: Pandy
authors.forename: K M
authors.initials: KM
authors.lastname: Crossley
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D057071:Patellofemoral Joint / Q000473:pathology*; D052097:Quadriceps Muscle / Q000473:pathology*