title: Functional performance is associated with both knee extensor and flexor muscle strength in patients scheduled for total knee arthroplasty: A cross-sectional study.
abstract: OBJECTIVE
  To determine whether muscle strength in patients scheduled for total knee arthroplasty is: (i) strongly associated with both measured functional performance and patient-reported measures; (ii) more closely associated with functional performance when measured during concentric than during isometric contractions; and (iii) more strongly related to the 30-s chair stand test than to the timed-up-and-go and walking measures.
  
  
  METHODS
  Cross-sectional-study.
  
  
  METHODS
  Fifty-nine patients (36 women, 23 men), mean age 70.4 years.
  
  
  METHODS
  Associations between muscle strength, measured functional performance, and patient-reported measures were calculated.
  
  
  RESULTS
  Both knee extensor and knee flexor strength were associated with performance-based measures. In general, concentric knee flexor muscle strength was more strongly associated with functional performance than was isometric knee flexor strength. Concentric and isometric knee extensor strength were of equal importance. The 30-s chair stand test was better than the timed-up-and-go and the walking tests at determining muscle strength.
  
  
  CONCLUSIONS
  Future rehabilitation programmes should include both the knee extensor muscles and the knee flexor muscles in order to improve functional performance. The 30-s chair stand test is a valid and clinical relevant proxy measure of knee extensor and knee flexor muscle strength.
authors: Department of Physical and Occupational Therapy,, Aarhus University Hospital, 8000 Aarhus, Denmark. bss@mph.au.dk.
authors: Birgit
authors: B
authors: Skoffer
authors: Ulrik
authors: U
authors: Dalgas
authors: Inger
authors: I
authors: Mechlenburg
authors: Kjeld
authors: K
authors: Søballe
authors: Thomas
authors: T
authors: Maribo
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000601:surgery; D015203:Reproducibility of Results; D016138:Walking / Q000502:physiology