title: The association of bone attrition with knee pain and  other MRI features of osteoarthritis.
abstract: OBJECTIVE
  To determine whether bone attrition (flattening or depression of the subchondral bone) was associated with the presence and severity of knee pain and to evaluate the coexistence of attrition and other MRI features likely associated with pain.
  
  
  METHODS
  Participants in the Framingham Osteoarthritis Study, a community cohort unselected for OA, answered questions about knee pain and underwent knee x rays and MRI. Attrition, bone marrow lesions (BMLs) and effusions were scored on MRI using the WORMS scale. We assessed attrition in knees with and without pain, and using logistic regression examined its association with pain adjusting for age, gender, Kellgren-Lawrence (K-L)grade, BMI, BML and effusion. We also explored the relation between attrition, pain severity and nocturnal pain.
  
  
  RESULTS
  Attrition (Grade >2) was present in 28% (167/592) of painful knees and in 10% (106/1035) of nonpainful knees (adjusted OR 1.6 (95% CI 1.1 to 2.2)). Of knees with OA (n=368), 74% had pain if attrition was present and 58% if it was absent (adjusted OR 1.2 (95%CI 0.7 to 2.0)). Of knees without OA (n=1222), pain was reported in 39% of knees with attrition and in 27%without it (adjusted OR 2.1 (95% CI 1.1 to 4.0)). We found no association between either attrition/pain severity or attrition/nocturnal pain. Attrition often co-occurred with other OA features associated with pain such as BMLs and effusions.
  
  
  CONCLUSIONS
  Attrition was associated independently with knee pain. Unlike knees without OA, the association was lost in OA knees where other pathological features that may cause pain also coexisted.
authors.affiliation: Clinical Epidemiology Reseach and Training Unit and the Department of Radiology, Boston University School of Medicine, Boston, MA, USA.
authors.forename: G
authors.initials: G
authors.lastname: Hernández-Molina
authors.forename: T
authors.initials: T
authors.lastname: Neogi
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: J
authors.initials: J
authors.lastname: Niu
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
authors.forename: S
authors.initials: S
authors.lastname: Reichenbach
authors.forename: F W
authors.initials: FW
authors.lastname: Roemer
authors.forename: C E
authors.initials: CE
authors.lastname: McLennan
authors.forename: D T
authors.initials: DT
authors.lastname: Felson
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000150:complications* / Q000473:pathology*; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement; D012720:Severity of Illness Index