title: Abnormalities identified in the knees of asymptomatic volunteers using peripheral magnetic resonance imaging.
abstract: OBJECTIVE
  To estimate the prevalence of bone and soft tissue abnormalities in asymptomatic knees using peripheral magnetic resonance imaging (pMRI) and to examine the relationship between these abnormalities and Kellgren-Lawrence (K-L) graded X-rays.
  
  
  METHODS
  Volunteers (20-68 years) with no history of knee pain, injury or bone or joint disease were recruited. Individuals underwent a single MRI scan and radiograph of their non-dominant knee. pMR images were acquired in sagittal plane using a 3-D gradient-echo protocol. Two radiologists graded the presence and severity of cartilage degeneration, osteophytosis, meniscal and ligamentous abnormalities, bone marrow edema and subchondral cysts. X-rays were acquired using a fixed-flexion technique and graded using the K-L scale.
  
  
  RESULTS
  Forty-four individuals, mean age (SD) 41.1 (14.2) years, participated. K-L grading of X-rays revealed 29 individuals were grade 0, 12 were grade 1 and 3 were grade 2. Five individuals showed evidence of cartilage lesions, the femoral trochlea, medial femur and patella being those regions most commonly affected. Twelve individuals (27.3%) showed evidence of osteophytosis, nine of whom did not show evidence on X-ray. Forty-three individuals showed evidence of at least one meniscal abnormality while 27 individuals (61.4%) had abnormalities in at least three of the four regions of the knee.
  
  
  CONCLUSIONS
  Our results suggest that osteophytes may be more prevalent in this population than radiographic data suggests due to the limitations of two-dimensional imaging. Meniscal degeneration or tears, a risk factor for knee osteoarthritis, are highly prevalent in asymptomatic individuals with the medial anterior and posterior horns being the most commonly affected regions.
authors.affiliation: Department of Medical Sciences, McMaster University, Hamilton, ON, Canada. karen.beattie@camris.ca
authors.forename: K A
authors.initials: KA
authors.lastname: Beattie
authors.forename: P
authors.initials: P
authors.lastname: Boulos
authors.forename: M
authors.initials: M
authors.lastname: Pui
authors.forename: J
authors.initials: J
authors.lastname: O'Neill
authors.forename: D
authors.initials: D
authors.lastname: Inglis
authors.forename: C E
authors.initials: CE
authors.lastname: Webber
authors.forename: J D
authors.initials: JD
authors.lastname: Adachi
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology; D002357:Cartilage Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008592:Menisci, Tibial / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index