title: Knee laxity after staircase exercise predicts radiographic disease progression in medial compartment knee osteoarthritis.
abstract: OBJECTIVE
  To evaluate whether increased laxity of the knee during daily physical activities such as stair climbing is associated with progression of knee joint osteoarthritis (OA).
  
  
  METHODS
  During the years 2001-2003, 136 patients with bilateral primary medial compartment knee joint OA were enrolled in this prospective study. Baseline data collected were body mass index (BMI), muscle power, radiographic joint space width, mechanical axis on standing radiography, and anteroposterior (AP) knee laxity before and after physical exercise. After 8 years of followup, 84 patients were reexamined to assess radiographic changes. Radiographic disease progression was defined as progression of >1 grade on the Kellgren/Lawrence scale.
  
  
  RESULTS
  AP knee laxity increased significantly after stair climbing. Patients with OA progression and those without progression did not differ significantly in age, sex, baseline quadriceps muscle strength, mechanical axis, joint space width, and AP knee laxity before exercise. The 2 groups of patients did, however, differ significantly in baseline BMI and change in AP knee laxity due to exercise. The risk of progression of knee OA increased 4.15-fold with each millimeter of increase in the change in AP knee laxity due to exercise and 1.24-fold with each point increase in the BMI.
  
  
  CONCLUSIONS
  Our results indicate that patients with OA progression have significantly greater changes in knee joint laxity during physical activities and a higher BMI than patients without OA progression. These findings suggest that larger changes in knee laxity during repetitive physical activities and a higher BMI play significant roles in the progression of knee OA.
authors.affiliation: University of Fukui, Fukui, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Kenzo
authors.initials: K
authors.lastname: Uchida
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Sato
authors.forename: Shuji
authors.initials: S
authors.lastname: Watanabe
authors.forename: Ai
authors.initials: A
authors.lastname: Yoshida
authors.forename: Makoto
authors.initials: M
authors.lastname: Wada
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Shimada
authors.forename: Jan Herman
authors.initials: JH
authors.lastname: Kuiper
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Baba
mesh_terms: D000368:Aged; D015992:Body Mass Index; D018450:Disease Progression; D015444:Exercise / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D005684:Gait; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors