title: One-year change in radiographic joint space width in patients with unilateral joint space narrowing: data from the Osteoarthritis Initiative.
abstract: OBJECTIVE
  To examine the rate of joint space width (JSW) loss in both knees of patients with unilateral medial joint space narrowing (JSN) at baseline.
  
  
  METHODS
  Cases were selected from a pool of 2,678 subjects enrolled in the Osteoarthritis Initiative cohort. Inclusion criteria for the present study were unilateral medial JSN, bilateral frequent knee pain, and body mass index (BMI) > or = 25 kg/m(2). Baseline and 1-year fixed flexion radiographs of both knees were read (blinded to time point) using an automated algorithm for minimum JSW and JSW at 4 fixed locations in the medial compartment.
  
  
  RESULTS
  Sixty-seven participants met the inclusion criteria: 43 women and 24 men, with mean +/- SD age 60 +/- 9 years and mean +/- SD BMI 31 +/- 4 kg/m(2). Thirty-seven subjects (55%) had > or = 1 definite tibiofemoral osteophyte. The average progression in no-JSN knees was comparable with that in JSN knees (approximately -0.2 mm/year). However, JSW change was more variable in no-JSN knees, resulting in standardized response means (SRMs; the mean/SD) of approximately -0.24 in no-JSN knees versus approximately -0.41 in JSN knees on average at the 4 fixed locations, and SRMs of -0.24 and -0.35, respectively, for minimum JSW. Young age and high BMI were associated with increased progression, especially in JSN knees.
  
  
  CONCLUSIONS
  JSN and no-JSN knees progressed at a comparable rate, but a wider distribution of JSW change in no-JSN knees resulted in a poorer sensitivity to change in these knees.
authors.affiliation: Eli Lilly, Indianapolis, Indiana, USA. benichouol@lilly.com
authors.forename: O D
authors.initials: OD
authors.lastname: Benichou
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: D R
authors.initials: DR
authors.lastname: Nelson
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
authors.forename: K
authors.initials: K
authors.lastname: Kwoh
authors.forename: S L
authors.initials: SL
authors.lastname: Myers
authors.forename: W
authors.initials: W
authors.lastname: Wirth
authors.forename: J
authors.initials: J
authors.lastname: Duryea
mesh_terms: D000367:Age Factors; D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008592:Menisci, Tibial / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D050177:Overweight / Q000150:complications; D011446:Prospective Studies; D011859:Radiography