title: Differences in sonographic characteristics of the vastus medialis obliquus between patients with patellofemoral pain syndrome and healthy adults.
abstract: BACKGROUND
  There is controversy regarding the relationship between patellofemoral pain syndrome (PFPS) and insufficiency of the vastus medialis obliquus (VMO). The conventional clinical practice of VMO strengthening for PFPS has been challenged for lack of evidence. The purpose of this study was to observe the difference in sonographic findings of the VMO between patients with PFPS and healthy adults.
  
  
  OBJECTIVE
  The morphological characteristics of the VMO are different between patients with PFPS and healthy adults.
  
  
  METHODS
  Case-control study; Level of evidence, 3.
  
  
  METHODS
  Fifty-four patients with PFPS and 54 age-, gender-, body height-, and body weight-matched healthy adults as controls were enrolled in the study to measure by sonography the insertion level, fiber angle, and volume of the VMO at its insertional portion to detect differences between patients with PFPS and healthy controls.
  
  
  RESULTS
  The insertion level, fiber angle, and VMO volume were all significantly smaller in the PFPS group than in the control group (P < .05). Multivariate analysis of variance has revealed a Wilks lambda value of .845 and an F value of 5.640 (P = .001).
  
  
  CONCLUSIONS
  There was a significant difference in the 3 VMO measures between patients with PFPS and the healthy controls. Individuals might be predisposed to PFPS by different VMO characteristics, including insertion level and fiber angle. The current study cannot determine whether the observed morphological differences were the results of atrophy in response to pain or if they represent dysplasia that was predisposed to pain development. The clinical manifestations of VMO characteristics should be thoroughly investigated in other populations.
  
  
  CONCLUSIONS
  The function of the VMO is important to consider in the rehabilitation of patients with PFPS.
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Mei-Hwa
authors.initials: MH
authors.lastname: Jan
authors.forename: Da-Hon
authors.initials: DH
authors.lastname: Lin
authors.forename: Jiu-Jenq
authors.initials: JJ
authors.lastname: Lin
authors.forename: Chien-Ho Janice
authors.initials: CH
authors.lastname: Lin
authors.forename: Cheng-Kung
authors.initials: CK
authors.lastname: Cheng
authors.forename: Yeong-Fwu
authors.initials: YF
authors.lastname: Lin
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging* / Q000502:physiology; D013624:Taiwan; D014463:Ultrasonography