title: Quadriceps femoris muscle function prior and after total knee arthroplasty in women with knee osteoarthritis.
abstract: OBJECTIVE
  The aim of the present study was to evaluate an isometric voluntary force generation and relaxation capacity of the quadriceps femoris (QF) muscle prior and after total knee arthroplasty (TKA).
  
  
  METHODS
  Isometric maximal voluntary contraction force, rate of force development, voluntary activation, half-relaxation time, and latency of contraction of the QF muscle were recorded in 12 female patients (aged 49-68 years) with knee osteoarthritis one day before, 3 and 6 months following TKA in the operated and nonoperated leg. Knee pain intensity was assessed by visual analog scale, and Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire was used to assess knee problems during daily living.
  
  
  RESULTS
  A significant decrease in knee pain and significant increase in KOOS were established after TKA. Maximal voluntary isometric force in the operated leg was lower (P < 0.05) before, 3 and 6 months after TKA as compared to the nonoperated leg. Rate of force development of the QF muscle in the operated leg compared to the nonoperated leg was significantly lower (P < 0.05) 3 and 6 months after TKA. Voluntary activation, latency of contraction, and half-relaxation time of the QF muscle did not differ significantly before, 3 and 6 months after TKA.
  
  
  CONCLUSIONS
  The present study indicated reduced maximal and explosive strength of quadriceps femoris muscle in the operated leg 3 and 6 months after TKA with no significant changes in voluntary activation, and capacity for rapid contraction and relaxation.
  
  
  METHODS
  Prospective comparative study, Level II.
authors.affiliation: Institute of Exercise Biology and Physiotherapy, University of Tartu, 5 Jakobi Street, 51014, Tartu, Estonia. Doris.Vahtrik@ut.ee
authors.forename: Doris
authors.initials: D
authors.lastname: Vahtrik
authors.forename: Helena
authors.initials: H
authors.lastname: Gapeyeva
authors.forename: Herje
authors.initials: H
authors.lastname: Aibast
authors.forename: Jaan
authors.initials: J
authors.lastname: Ereline
authors.forename: Tatjana
authors.initials: T
authors.lastname: Kums
authors.forename: Tiit
authors.initials: T
authors.lastname: Haviko
authors.forename: Aare
authors.initials: A
authors.lastname: Märtson
authors.forename: Galina
authors.initials: G
authors.lastname: Schneider
authors.forename: Mati
authors.initials: M
authors.lastname: Pääsuke
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation; D001696:Biomechanical Phenomena; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009119:Muscle Contraction; D053580:Muscle Strength; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D052097:Quadriceps Muscle / Q000503:physiopathology*; D016896:Treatment Outcome