title: Assessing bone loss on radiographs of the knee in osteoarthritis: a cross-sectional study.
abstract: OBJECTIVE
  The only established system to grade subchondral bone attrition in knee osteoarthritis (OA) has low interobserver reliability. In this study, our aim was to convert this system into a reliable tool for the assessment of subchondral bone loss in knee OA.
  
  
  METHODS
  Templates that were designed to outline the normal contours of the knee were overlaid onto conventional radiographs of a random sample of 100 knees of OA patients who were awaiting total knee replacement (TKR). Seventy-five films from individuals with chronic knee pain who were not awaiting TKR and 75 films from asymptomatic control subjects were also assessed. Bone loss was graded from 0 (no attrition) to 3 (severe attrition of >10 mm); other established radiologic features were also graded. Spearman's rho was used to determine the correlation of attrition scores with other features, and logistic regression was used to explore whether definite bone attrition was associated with night pain.
  
  
  RESULTS
  The inter- and intraobserver reliability values were high for attrition scores and for the presence of definite attrition (score > or =2). Bone attrition was evident in 62% of films from patients awaiting TKR, in 9% of films from individuals with chronic knee pain who were not awaiting TKR, and in 1% of films from controls. In all groups, the correlation between attrition and other features was weak to moderate. There was a nonsignificant association between definite bone attrition and night pain.
  
  
  CONCLUSIONS
  Bone attrition is an additional dimension of knee OA that can be measured reliably. Definite attrition may be associated with night pain.
authors.affiliation: University of Bristol, Bristol, UK.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dieppe
authors.forename: Stephan
authors.initials: S
authors.lastname: Reichenbach
authors.forename: Susan
authors.initials: S
authors.lastname: Williams
authors.forename: Paul
authors.initials: P
authors.lastname: Gregg
authors.forename: Iain
authors.initials: I
authors.lastname: Watt
authors.forename: Peter
authors.initials: P
authors.lastname: Jüni
mesh_terms: D000368:Aged; D001862:Bone Resorption / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D002908:Chronic Disease; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D016015:Logistic Models; D008297:Male; D015588:Observer Variation; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D010146:Pain / Q000453:epidemiology / Q000503:physiopathology; D011859:Radiography; D016037:Single-Blind Method