title: Relationship between knee pain and the presence, location, size and phenotype of femorotibial denuded areas of subchondral bone as visualized by MRI.
abstract: OBJECTIVE
  Conflicting associations between imaging biomarkers and pain in knee osteoarthritis (OA) have been reported. A relation between pain and denuded areas of subchondral bone (dABs) has been suggested and this study explores this relationship further by relating the presence, phenotype, location and size of dABs to different measures of knee pain.
  
  
  METHODS
  633 right knees from the Osteoarthritis Initiative (OAI) (250 men, age 61.7 ± 9.6 yrs, BMI 29.4 ± 4.7 kg/m(2)) were included. Manual segmentation of the femorotibial cartilage plates was performed on 3 T coronal fast low angle shot with water excitation (FLASHwe) images. dABs were defined as areas where the subchondral bone was uncovered by cartilage. The following measures of pain were used: weightbearing-, non-weightbearing-, moderate-to-severe-, infrequent- and frequent knee pain.
  
  
  RESULTS
  Using pain measures from subjects without dABs as a reference, those with at least one dAB had a 1.64-fold higher prevalence ratio [PR, 95% confidence interval (CI) 1.24-2.18] to have frequent and 1.45-fold higher for moderate-to-severe knee pain (95% CI 1.13-1.85). Subjects with dABs in central subregions had a 1.53-fold increased prevalence of having weightbearing pain (95% CI 1.20-1.97), especially when the central subregion was moderately (>10%) denuded (PR 1.81, 95% CI 1.35-2.42). Individuals with cartilage-loss-type dABs had a slightly higher prevalence (PR 1.13, 95% CI 1.00-1.27) of having frequent knee pain compared to individuals with intra-chondral-osteophyte-type dABs.
  
  
  CONCLUSIONS
  This study supports a positive relation between femorotibial dABs and knee pain, especially when the dABs are located centrally (i.e., in weightbearing regions) or when the respective central subregion is moderately denuded.
authors: Paracelsus Medical University, Salzburg, Austria. sebastian.cotofana@pmu.ac.at
authors: S
authors: S
authors: Cotofana
authors: B T
authors: BT
authors: Wyman
authors: O
authors: O
authors: Benichou
authors: D
authors: D
authors: Dreher
authors: M
authors: M
authors: Nevitt
authors: J
authors: J
authors: Gardiner
authors: W
authors: W
authors: Wirth
authors: W
authors: W
authors: Hitzl
authors: C K
authors: CK
authors: Kwoh
authors: F
authors: F
authors: Eckstein
authors: R B
authors: RB
authors: Frobell
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000473:pathology*; D002356:Cartilage / Q000473:pathology; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000453:epidemiology* / Q000473:pathology*; D054850:Osteophyte / Q000453:epidemiology / Q000473:pathology; D010147:Pain Measurement; D010641:Phenotype; D015995:Prevalence; D012720:Severity of Illness Index; D013977:Tibia / Q000473:pathology
keywords: Cartilage; Denuded area of subchondral bone; MRI; Pain