title: Minimum detectable change for knee joint contact force estimates using an EMG-driven model.
abstract: Adequate test-retest reliability of model estimates is a necessary precursor to examining treatment effects or longitudinal changes in individuals.
  
  
  OBJECTIVE
  The purpose of this study was to establish thresholds for minimal detectable change (MDC) for joint contact forces obtained using a patient specific EMG-driven musculoskeletal model of the knee.
  
  
  METHODS
  A sample of young, active individuals was selected for this study, and subjects were tested on 2 separate days. Three-dimensional motion analysis with electromyography (EMG) was used to obtain data from each subject during gait for model input. An EMG-driven modeling approach was used to estimate joint contact forces at each session.
  
  
  RESULTS
  MDC's for contact force variables ranged from 0.30 to 0.66 BW. The lowest MDC was for peak medial compartment force (0.30 BW) and the highest was for peak tibiofemoral contact force (0.66 BW). Test-retest reliability coefficients were also reported for comparison with previous work.
  
  
  CONCLUSIONS
  Using the present model, changes in joint contact forces between baseline and subsequent measurements that are greater than these MDCs are greater than typical day-to-day variation and can be identified as real change.
authors.affiliation: Biomechanics and Movement Science Program, University of Delaware, Newark, DE, United States; Delaware Rehabilitation Institute, University of Delaware, Newark, DE, United States.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Gardinier
authors.forename: Kurt
authors.initials: K
authors.lastname: Manal
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Buchanan
authors.forename: Lynn
authors.initials: L
authors.lastname: Snyder-Mackler
mesh_terms: D004576:Electromyography / Q000379:methods; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007717:Knee; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology*; D015203:Reproducibility of Results; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
keywords: Contact force; Electromyography; Minimal detectable change; Musculoskeletal model; Reliability