title: Vastus medialis obliquus atrophy: does it exist in patellofemoral pain syndrome?
abstract: BACKGROUND
  Quadriceps atrophy and in particular atrophy of the vastus medialis obliquus (VMO) muscle have been frequently related with patellofemoral pain syndrome (PFPS), despite very little objective evidence.
  
  
  OBJECTIVE
  Patients with PFPS exhibit atrophy of the VMO in comparison with healthy controls.
  
  
  METHODS
  Case-control study; Level of evidence, 3.
  
  
  METHODS
  Forty-six patients with PFPS and 30 healthy control persons with similar age, gender, body mass index, and activity index distributions underwent magnetic resonance imaging (MRI) of the quadriceps. The muscle size was determined by calculating the cross-sectional area of the total quadriceps and its components.
  
  
  RESULTS
  The cross-sectional area (CSA) of the VMO was significantly smaller in the PFPS group than in the control group (16.67 ± 4.97 cm(2) vs 18.36 ± 5.25 cm(2)) (P = .040). A tendency was noted for a smaller total quadriceps CSA for the PFPS patients at midthigh level (66.99 ± 15.06 cm(2) vs 70.83 ± 15.30 cm(2)) (P = .074).
  
  
  CONCLUSIONS
  This is the first study to examine VMO size in PFPS patients by MRI. Patients with patellofemoral problems exhibited atrophy of the VMO. Although it is not clear whether this atrophy is a result or a cause of PFPS, the results of this study do show that atrophy of the VMO is a contributing factor in PFPS. Longitudinal, prospective studies are needed to establish the cause-effect relation of VMO atrophy and PFPS.
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium. e.pattyn@UGent.be
authors.forename: Els
authors.initials: E
authors.lastname: Pattyn
authors.forename: Peter
authors.initials: P
authors.lastname: Verdonk
authors.forename: Adelheid
authors.initials: A
authors.lastname: Steyaert
authors.forename: Luc
authors.initials: L
authors.lastname: Vanden Bossche
authors.forename: Wouter
authors.initials: W
authors.lastname: Van den Broecke
authors.forename: Youri
authors.initials: Y
authors.lastname: Thijs
authors.forename: Erik
authors.initials: E
authors.lastname: Witvrouw
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009133:Muscular Atrophy / Q000150:complications* / Q000473:pathology*; D015588:Observer Variation; D009929:Organ Size; D046788:Patellofemoral Pain Syndrome / Q000150:complications*; D052097:Quadriceps Muscle / Q000473:pathology*; D018709:Statistics, Nonparametric; D055815:Young Adult