title: Patellar tilt correlates with vastus lateralis: vastus medialis activation ratio in maltracking patellofemoral pain patients.
abstract: Patellofemoral (PF) pain is a common ailment of the lower extremity. A theorized cause for pain is patellar maltracking due to vasti muscle activation imbalance, represented as large vastus lateralis:vastus medialis (VL:VM) activation ratios. However, evidence relating vasti muscle activation imbalance to patellar maltracking is limited. The purpose of this study was to investigate the relationship between VL:VM activation ratio and patellar tracking measures, patellar tilt and bisect offset, in PF pain subjects and pain-free controls. We evaluated VL:VM activation ratio and VM activation delay relative to VL activation in 39 PF pain subjects and 15 pain-free controls during walking. We classified the PF pain subjects into normal tracking and maltracking groups based on patellar tilt and bisect offset measured from weight-bearing magnetic resonance imaging. Patellar tilt correlated with VL:VM activation ratio only in PF pain subjects classified as maltrackers. This suggests that a clinical intervention targeting vasti muscle activation imbalance may be effective only in PF pain subjects classified as maltrackers.
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, USA. spal5@stanford.edu
authors.forename: Saikat
authors.initials: S
authors.lastname: Pal
authors.forename: Thor F
authors.initials: TF
authors.lastname: Besier
authors.forename: Christine E
authors.initials: CE
authors.lastname: Draper
authors.forename: Michael
authors.initials: M
authors.lastname: Fredericson
authors.forename: Garry E
authors.initials: GE
authors.lastname: Gold
authors.forename: Gary S
authors.initials: GS
authors.lastname: Beaupre
authors.forename: Scott L
authors.initials: SL
authors.lastname: Delp
mesh_terms: D000328:Adult; D017760:Bone Malalignment / Q000150:complications / Q000503:physiopathology*; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D010329:Patella / Q000503:physiopathology*; D057071:Patellofemoral Joint / Q000503:physiopathology; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D012737:Sex Factors; D016138:Walking / Q000502:physiology; D016474:Weight-Bearing; D055815:Young Adult
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