title: Reliability and reference values of two clinical measurements of dynamic and static knee position in healthy children.
abstract: OBJECTIVE
  The purposes of this study were to evaluate reliability of the Single-limb mini squat test (a dynamic measure of medio-lateral knee position) and the Quadriceps-angle (Q-angle) (a static measure of medio-lateral knee position), present paediatric reference values of the Q-angle, and evaluate the association between the tests.
  
  
  METHODS
  Two hundred and forty-six healthy children (9-16 years) were included (intra/inter-rater reliability for Q-angle (n = 37/85) and for Single-limb mini squat test (n = 33/28)). Dynamic medio-lateral knee position was assessed by the Single-limb mini squat test. Static medio-lateral knee position was evaluated by the Q-angle.
  
  
  RESULTS
  The reliability of the Single-limb mini squat test was found to be moderate (kappa 0.48-0.57, 95% CI 0.16-0.85, 76-79% agreement). Fair to moderate reliability (ICC 0.35-0.42, 95% CI 0.11-0.66, SEM 1.4°-1.9°, n.s.) of the Q-angle measurements was found. Reference values for the Q-angle (mean 13.5° (1.9)-15.3° (2.8)) varies with age and gender. No associations were found between dynamic and static measures.
  
  
  CONCLUSIONS
  The Single-limb mini squat test showed a moderate reliability and the Q-angle showed a fair to moderate reliability. A difference found for age and gender was lower than 5° and may not be clinical significant. No association were found between the two tests, indicating dynamic and static knee position being two different concepts. In a clinical perspective, we suggest that the Single-limb mini squat test is a contribution to the available tool box for evaluation of dynamic medio-lateral knee position in children, although the Q-angle may not be used before more research has been done justifying its use.
authors.affiliation: Department of Women's & Children's Health, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Ortqvist
authors.forename: Eva B
authors.initials: EB
authors.lastname: Moström
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Roos
authors.forename: Pia
authors.initials: P
authors.lastname: Lundell
authors.forename: Per-Mats
authors.initials: PM
authors.lastname: Janarv
authors.forename: Suzanne
authors.initials: S
authors.lastname: Werner
authors.forename: Eva W
authors.initials: EW
authors.lastname: Broström
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002648:Child; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results