title: Leg extensor power and quadriceps strength: an assessment of repeatability in patients with osteoarthritic knees.
abstract: OBJECTIVE
  To assess the repeatability of two muscle function measures -- leg extensor power (LEP) and isometric quadriceps force (IQF) -- in a population of patients with osteoarthritis of the knee.
  
  
  METHODS
  Repeat measures of LEP and IQF at 25 degrees and 50 degrees knee flexion were taken within seven days. Both legs were measured and a numerical rating scale was used to assess pain on the two occasions.
  
  
  METHODS
  Patients who were on a waiting list for a primary unilateral knee replacement for osteoarthritis were invited to take part in the study.
  
  
  METHODS
  The physiotherapy department of a National Health Service Orthopaedic Hospital in Oxford, UK.
  
  
  METHODS
  Subjects were measured using a Kin-Com dynamometer to assess maximum isometric force and a leg extensor power rig to assess maximum single leg explosive power.
  
  
  RESULTS
  Twenty-six patients (mean age: 72 years; SD: 8 years; range: 50-87 years) were included in the study following informed consent. A weak relationship was found between LEP, IQF and pain scores which reached the 5% significance level for the LEP measures only. The level of repeatability for both measures was found to be acceptable.
  
  
  CONCLUSIONS
  Both LEP and IQF are recommended as repeatable measures for assessment of muscle function in patients with osteoarthitis of the knee. However, the LEP rig has the added advantage of being quicker, cheaper and simpler to use in the clinical setting.
authors.affiliation: Outpatient Department, Nuffield Orthopaedic Centre NHS Trust, Oxford, UK.
authors.forename: S
authors.initials: S
authors.lastname: Robertson
authors.forename: H
authors.initials: H
authors.lastname: Frost
authors.forename: H
authors.initials: H
authors.lastname: Doll
authors.forename: J J
authors.initials: JJ
authors.lastname: O'Connor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D010003:Osteoarthritis / Q000175:diagnosis* / Q000534:rehabilitation; D015203:Reproducibility of Results