title: Quadriceps femoris strength and sagittal-plane knee biomechanics during stair ascent in individuals with articular cartilage defects in the knee.
abstract: BACKGROUND
  Few objective data are available regarding strength and movement patterns in individuals with articular cartilage defects (ACDs) of the knee.
  
  
  OBJECTIVE
  To test the following hypotheses: (1) The involved limb of individuals with ACDs would demonstrate lower peak knee-flexion angle, peak internal knee-extension moment, and peak vertical ground-reaction force (vGRF) than the contralateral limb and healthy controls. (2) On the involved limb of individuals with ACDs, quadriceps femoris strength would positively correlate with peak knee-flexion angle, peak internal knee-extension moment, and peak vGRF.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  Biomechanics research laboratory.
  
  
  METHODS
  11 individuals with ACDs in the knee who were eligible for surgical cartilage restoration and 10 healthy controls.
  
  
  METHODS
  Quadriceps femoris strength was quantified as peak isometric knee-extension torque via an isokinetic dynamometer. Sagittal-plane knee kinematics and kinetics were measured during the stance phase of stair ascent with 3-dimensional motion analysis.
  
  
  METHODS
  Quadriceps strength and knee biomechanics during stair ascent were compared between the involved and contralateral limbs of participants with ACD (paired t tests) and with a control group (independent-samples t tests). Pearson correlations evaluated relationships between strength and stair-ascent biomechanics.
  
  
  RESULTS
  Lower quadriceps strength and peak internal knee-extension moments were observed in the involved limb than in the contralateral limb (P < .01) and the control group (P < .01). For the involved limb of the ACD group, quadriceps femoris strength was strongly correlated (r = .847) with involved-limb peak internal knee-extension moment and inversely correlated (r = -.635) with contralateral peak vGRF.
  
  
  CONCLUSIONS
  Individuals with ACDs demonstrated deficits in quadriceps femoris strength with associated alterations in movement patterns during stair ascent. The results of this study are not comprehensive; further research is needed to understand the physiological characteristics, activity performance, and movement quality in this population.
authors.affiliation: School of Health and Rehabilitation Sciences, The Ohio State University, Columbus, OH.
authors.forename: Louise M
authors.initials: LM
authors.lastname: Thoma
authors.forename: David C
authors.initials: DC
authors.lastname: Flanigan
authors.forename: Ajit M
authors.initials: AM
authors.lastname: Chaudhari
authors.forename: Robert A
authors.initials: RA
authors.lastname: Siston
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Best
authors.forename: Laura C
authors.initials: LC
authors.lastname: Schmitt
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000293:injuries* / Q000601:surgery; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000534:rehabilitation* / Q000601:surgery; D016014:Linear Models; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D019415:Torque; D055815:Young Adult