title: Validity and internal consistency of the international knee documentation committee subjective knee evaluation form in children and adolescents.
abstract: BACKGROUND
  The International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form (IKDC Knee Form) is a valid, reliable, and responsive measure of knee-related symptoms, function, and sports activities in adults. Despite the incidence of knee injuries in younger individuals, the measurement characteristics of the IKDC Knee Form have not been established. Hypothesis/
  
  
  OBJECTIVE
  The purpose of this study was to investigate the validity and internal consistency of the IKDC Knee Form in pediatric, adolescent, and young adult patients with a variety of knee conditions. The authors hypothesized that the IKDC Knee Form would be a valid and consistent measure of knee function in these age groups.
  
  
  METHODS
  Cohort study (diagnosis); Level of evidence, 2.
  
  
  METHODS
  The IKDC Knee Form and Pediatric Quality of Life Inventory 4.0 Generic Core Scales (PedsQL) physical functioning component were administered to 673 individuals between 6 and 18 years of age. The internal consistency and validity of the IKDC Knee Form were determined for the entire cohort and for age group cohorts (pediatric, 6-12 years; adolescent, 13-15 years; young adult, 16-18 years) using the PedsQL physical functioning component for comparison.
  
  
  RESULTS
  The results were similar across all age groups. In the original format, internal consistency was high and factor analysis showed a single, dominant component underlying the item responses for each age group. Items 2, 3, and 6 may contribute to measurement error in young individuals. Correlation between the IKDC Knee Form and PedsQL physical functioning component score was moderately high for the entire cohort (r = .83) and for all age groups (pediatric, r = .84; adolescent, r = .84; young adult, r = .79).
  
  
  CONCLUSIONS
  In its current form, the IKDC Knee Form is a valid and consistent knee-specific measure of symptoms, function, and sports activity in individuals between the ages of 6 and 18 years with a variety of knee problems. Further work is needed to establish the reliability and responsiveness of the IKDC Knee Form for this age group.
authors.affiliation: Cincinnati Children’s Hospital Medical Center, Ohio 45229, USA. laura.schmitt@cchmc.org
authors.forename: Laura C
authors.initials: LC
authors.lastname: Schmitt
authors.forename: Mark V
authors.initials: MV
authors.lastname: Paterno
authors.forename: Samuel
authors.initials: S
authors.lastname: Huang
mesh_terms: D000293:Adolescent; D000367:Age Factors; D018771:Arthralgia / Q000175:diagnosis / Q000473:pathology; D001265:Athletic Injuries / Q000175:diagnosis* / Q000473:pathology / Q000523:psychology; D002648:Child; D015331:Cohort Studies; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D007718:Knee Injuries / Q000175:diagnosis* / Q000473:pathology / Q000523:psychology; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D010147:Pain Measurement; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D013223:Statistics as Topic; D011795:Surveys and Questionnaires / Q000592:standards*