title: The effect of postoperative range of motion on functional activities after posterior cruciate-retaining total knee arthroplasty.
abstract: BACKGROUND
  Range of motion is recognized as an important indicator of the success of a total knee replacement; however, an optimal range of motion has yet to be defined. This study was designed to determine the optimal range of motion for knee function after total knee arthroplasty with a posterior cruciate-retaining prosthesis.
  
  
  METHODS
  We retrospectively reviewed 5556 primary total knee arthroplasties performed with posterior cruciate-retaining prostheses between 1983 and 2003. The relationship between postoperative range of motion and pain, walking ability, stair-climbing ability, and knee function scores was examined at three to five years postoperatively. The relationship between a postoperative flexion contracture or hyperextension and knee function was also examined.
  
  
  RESULTS
  Patients with 128 degrees to 132 degrees of motion obtained the highest scores for pain, walking, and knee function and the highest Knee Society scores. The outcomes became substantially compromised with motion of <118 degrees . Patients with 133 degrees to 150 degrees of motion had the highest scores for stair-climbing. A postoperative flexion contracture and hyperextension were associated with lower scores for pain, walking, stair-climbing, and knee function.
  
  
  CONCLUSIONS
  The best functional results following total knee arthroplasty are achieved with 128 degrees to 132 degrees of motion. A postoperative flexion contracture and hyperextension of >or=10 degrees are associated with a poorer outcome except that stair-climbing is improved with more motion.
authors.affiliation: The Center for Hip and Knee Surgery, St. Francis Hospital, 1199 Hadley Road, Mooresville, IN 46158, USA. marittermd@yahoo.com
authors.forename: Merrill A
authors.initials: MA
authors.lastname: Ritter
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Lutgring
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Davis
authors.forename: Michael E
authors.initials: ME
authors.lastname: Berend
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods / Q000534:rehabilitation; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D010020:Osteonecrosis / Q000601:surgery; D010147:Pain Measurement; D011184:Postoperative Period; D016059:Range of Motion, Articular; D020127:Recovery of Function / Q000502:physiology*; D013647:Task Performance and Analysis; D016138:Walking