title: Knee joint stabilization therapy in patients with osteoarthritis of the knee and knee instability: subgroup analyses in a randomized, controlled trial.
abstract: OBJECTIVE
  To test whether knee stabilization therapy, prior to strength/functional training, may have added value in reducing activity limitations only in patients with knee osteoarthritis who have knee instability and (i) low upper leg muscle strength, (ii) impaired knee proprioception, (iii) high knee laxity, or (iv) frequent episodes of knee instability.
  
  
  METHODS
  Subgroup analyses in a randomized controlled trial comparing 2 exercise programmes (with/without knee stabilization therapy) (STABILITY; NTR1475).
  
  
  METHODS
  Participants from the STABILITY-trial with clinical knee osteoarthritis and knee instability (n = 159).
  
  
  METHODS
  Effect modification by upper leg muscle strength, knee proprioception, knee laxity, and patient-reported knee instability were determined using the interaction terms "treatment group subgroup factor", with the outcome measures WOMAC physical function (primary), numeric rating scale pain and the Get up and Go test (secondary).
  
  
  RESULTS
  Effect modification by muscle strength was found for the primary outcome (p = 0.01), indicating that patients with greater muscle strength tend to benefit more from the experimental programme with additional knee stabilization training, while patients with lower muscle strength benefit more from the control programme.
  
  
  CONCLUSIONS
  Knee stabilization therapy may have added value in patients with instability and strong muscles. Thus it may be beneficial if exercises target muscle strength prior to knee stabilization.
authors.affiliation: , Amsterdam Rehabilitation Research Center, Reade, 1056AB Amsterdam, The Netherlands. j.knoop@reade.nl.
authors.forename: Jesper
authors.initials: J
authors.lastname: Knoop
authors.forename: Marike
authors.initials: M
authors.lastname: van der Leeden
authors.forename: Leo D
authors.initials: LD
authors.lastname: Roorda
authors.forename: Carina A
authors.initials: CA
authors.lastname: Thorstensson
authors.forename: Martin
authors.initials: M
authors.lastname: van der Esch
authors.forename: Wilfred F
authors.initials: WF
authors.lastname: Peter
authors.forename: Mariëtte
authors.initials: M
authors.lastname: de Rooij
authors.forename: Willem F
authors.initials: WF
authors.lastname: Lems
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
authors.forename: Martijn P M
authors.initials: MP
authors.lastname: Steultjens
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000534:rehabilitation*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000534:rehabilitation*; D057566:Self Report; D012720:Severity of Illness Index; D016896:Treatment Outcome