title: Lower extremity performance following ACL rehabilitation in the KANON-trial: impact of reconstruction and predictive value at 2 and 5 years.
abstract: BACKGROUND
  The additional effect of anterior cruciate ligament (ACL) reconstruction on muscle strength and physical performance after a structured exercise programme is not well understood.
  
  
  OBJECTIVE
  To investigate and compare muscle strength and physical performance test results after a structured exercise programme, in young active adults with acute ACL injury, between those treated with and without ACL reconstruction (ACLR) and to evaluate these test results as predictors of clinical outcomes 2 and 5 years after injury.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  In a treatment randomised controlled trial of acute ACL injury (the KANON-study), 87/121 young active adults underwent two muscle strength tests and five physical performance tests after a structured exercise programme (median 37 (IQR 24) weeks after injury). Results were presented and compared as limb symmetry indices (LSI); endpoints in predictive analyses were having a delayed ACLR over the first 5 years and self-reported knee function (Knee injury and Osteoarthritis Outcome Score; KOOS4) at 2 and 5 years.
  
  
  RESULTS
  Overall, 74-95% of patients had LSI≥90% in the individual tests, with no difference between treatment groups (p=0.08-0.92). Results of the one-leg rise tests predicted KOOS₄ at 2 and 5 years (R²=0.25 and 0.24, p=0.001 and 0.002) and vertical hop results predicted having a delayed ACLR over a 5-year course after injury (p=0.048) in those starting with exercise alone (n=21).
  
  
  CONCLUSIONS
  After an acute ACL tear, the majority of young active adults regain physical performance and muscle strength after a structured exercise programme, with or without surgical reconstruction. Poor physical performance at the end of rehabilitation predicted worse patient-reported outcomes at 2 and 5 years regardless of treatment.
  
  
  BACKGROUND
  ISRCTN84752559.
authors.affiliation: Department of Orthopedics, Clinical Sciences Malmö, Lund University, , Malmö, Sweden.
authors.forename: Ylva B
authors.initials: YB
authors.lastname: Ericsson
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Roos
authors.forename: Richard B
authors.initials: RB
authors.lastname: Frobell
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000534:rehabilitation*; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D012421:Rupture / Q000503:physiopathology / Q000601:surgery
keywords: Exercise Rehabilitation; Knee ACL; Knee Injuries; Physiotherapy; Strength Isometric Isokinetic