title: Natural course of knee osteoarthritis in middle-aged subjects with knee pain: 12-year follow-up using clinical and radiographic criteria.
abstract: OBJECTIVE
  To explore the natural course of knee osteoarthritis (OA) in a middle-aged population with chronic knee pain.
  
  
  METHODS
  A population-based sample of 143 subjects (mean age 45 (range 35-54), 44% women) with knee pain (>3 months) at inclusion was studied. Weight-bearing posteroanterior tibiofemoral (TF) radiographs were obtained at baseline and 12 years later, and classified according to Kellgren/Lawrence (K/L). Patellofemoral (PF) OA was determined at 5- and 12-years' follow-up using a skyline view and a cut-off point of <5 mm joint space width. The ACR clinical criteria were used at baseline.
  
  
  RESULTS
  Seventy-six (53%) had no TF OA (K/L 0) at baseline, but 49 had clinical OA. Overall, 65/76 (86%) developed incident TF OA over 12 years (K/L >or=1): 44/49 (90%) of the subjects with clinical OA and 21/27 (78%) without clinical OA. Progression was found in 65/67 (97%) with TF OA at baseline. Of the 84 with no PF OA at the 5-year examination, 26 (31%) developed PF OA over 7 years.
  
  
  CONCLUSIONS
  A majority of the subjects with chronic knee pain developed knee OA over 12 years. It is concluded that knee pain is often the first sign of knee OA.
authors.affiliation: Research and Development Centre, Spenshult, S-313 92 Oskarström, Sweden. carina.thorstensson@spenshult.se
authors.forename: C A
authors.initials: CA
authors.lastname: Thorstensson
authors.forename: M L E
authors.initials: ML
authors.lastname: Andersson
authors.forename: H
authors.initials: H
authors.lastname: Jönsson
authors.forename: T
authors.initials: T
authors.lastname: Saxne
authors.forename: I F
authors.initials: IF
authors.lastname: Petersson
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D002908:Chronic Disease; D042241:Early Diagnosis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology; D011379:Prognosis; D011859:Radiography; D013548:Sweden / Q000453:epidemiology