title: Knee joint forces during isokinetic knee extensions: a case study.
abstract: OBJECTIVE
  To describe the procedures to obtain knee joint forces during isokinetic knee extensions and evaluate the patellar ligament force, quadriceps tendon force, patellofemoral and tibiofemoral joint forces at different speeds measured from a female subject.
  
  
  METHODS
  A technical note with a case study.
  
  
  BACKGROUND
  Two previous studies examined knee joint forces during isokinetic knee extension using different techniques reported inconsistent findings. Also, the highest speed used in these two studies (180 degrees s(-1)) were much lower than the maximum speeds available in modern isokinetic dynamometers.
  
  
  METHODS
  The subject performed maximum effort isokinetic knee extensions at 16 different speeds ranged from 25 to 400 degrees s(-1). The gravitational and inertial effects were included in determining the resultant knee torque. Knee radiographs were used to determine the knee joint geometry. A combination of knee torque and geometric data was used to determine different knee joint forces.
  
  
  RESULTS
  All knee joint forces were found to decrease with increasing isokinetic speed. The tibiofemoral shears forces indicated that the anterior cruciate ligament was loaded throughout the range of motion.
  
  
  CONCLUSIONS
  The magnitudes of knee joint forces are largely depending on the knee torque values.
  
  
  CONCLUSIONS
  Isokinetic knee extensions are considered appropriate for the early part of the rehabilitation for patients with knee dysfunctions due to the lesser demand of coordination. However, to reduce the knee joint forces, submaximal efforts at lower speeds or maximal efforts at higher speeds are recommended.
authors.affiliation: Department of Kinesiology, University of Illinois at Urbana-Champaign, Urbana, USA. j-chow1@uiuc.edu
authors.forename: J W
authors.initials: JW
authors.lastname: Chow
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010329:Patella / Q000502:physiology; D013977:Tibia / Q000502:physiology