title: Subjective vs objective predictors of functional knee joint performance in anterior cruciate ligament-reconstructed patients--do we need both?
abstract: BACKGROUND
  Associations between objective and subjective measures of knee function may facilitate rehabilitation in ACL-patients.
  
  
  OBJECTIVE
  The aim of this study is to investigate if a test-battery of functional and/or muscle outcomes are associated with Knee osteoarthritis outcome score (KOOS) subscales (Sport/Rec and QOL) in ACL-reconstructed patients.
  
  
  METHODS
  23 hamstring auto-graft ACL-reconstructed men (mean age: 27.2 standard deviation 7.5 years, BMI: 25.4 standard deviation 3.2 time since surgery: 27 standard deviation 7 months) completed KOOS-questionnaire and an objective test-battery: (i) one-leg maximal jump for distance (OLJD), isometric maximal voluntary contraction (MVC) for (ii) knee extensors and (iii) flexors, and (iv) maximal counter movement jump (CMJ). Sagittal kinematic data were recorded during CMJ using a 6-camera Vicon MX system. Multilevel linear regression analysis was used to determine the strength of associations between KOOS parameters (Sport/Rec and QOL) that a priori were defined as dependent variables and 4 models of independent outcomes from the test-battery.
  
  
  RESULTS
  Moderate associations between OLJD and Sport/Rec (r(2)=0.26, p<0.01) and QOL (r(2)=0.26, p<0.01) were observed (Model 1). Adding knee extensor or flexor MVC to the analysis (Model 2) increased the strength of the associations (up to r(2)=0.53, p<0.01, and r(2)=0.31, p=0.02 for Sport/Rec and QOL, respectively). Adding both knee extensor and knee flexor MVC to the analysis (Model 3) did not improve the regression model and only minor increases were observed when including kinematic data of CMJ (Model 4).
  
  
  CONCLUSIONS
  Moderate-to-large proportion (31-53%) of the variation in KOOS was explained by OLJD and MVC which may add to design effective future rehabilitation interventions for ACL-patients.
authors.affiliation: Orthopaedic Research Unit, Department of Orthopaedics and Traumatology, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Denmark. Electronic address: ahlarsen@health.sdu.dk.
authors.forename: Anders
authors.initials: A
authors.lastname: Holsgaard-Larsen
authors.affiliation: Orthopaedic Research Unit, Department of Orthopaedics and Traumatology, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Denmark.
authors.forename: Carsten
authors.initials: C
authors.lastname: Jensen
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Aagaard
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D001696:Biomechanical Phenomena / Q000502:physiology; D003430:Cross-Sectional Studies; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D017063:Outcome Assessment, Health Care; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*; D015203:Reproducibility of Results; D012649:Self Concept; D057566:Self Report; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
keywords: ACL; Biomechanical analysis; KOOS; Muscle strength; Reconstruction