title: Pre-radiographic osteoarthritic changes are highly prevalent in the medial patella and medial posterior femur in older persons: Framingham OA study.
abstract: OBJECTIVE
  To determine which subregions of the knee joint have a high prevalence of pre-radiographic osteoarthritic changes, i.e., cartilage damage and osteophytes that can only be detected by magnetic resonance imaging (MRI), in radiographically normal knees.
  
  
  METHODS
  Institutional Review Board approval and written informed consent from all participants was obtained. Data was collected from a community cohort in Framingham, MA, involving people aged 50-79. Participants underwent weight-bearing posteroanterior and lateral knee radiography with the fixed-flexion protocol, and 1.5 T MRI. Knees without radiographic osteoarthritis (Kellgren Lawrence grade 0 for the tibiofemoral joint and absence of any osteophytes or joint space narrowing in the patellofemoral joint) were included. The knee joint was divided into 14 subregions for cartilage and 16 subregions for osteophytes, and prevalence and severity of cartilage damage (grade 0-6) and osteophytes (grade 0-7) were semiquantitatively assessed using the Whole Organ Magnetic Resonance Imaging Score (WORMS).
  
  
  RESULTS
  The mean age of 696 participants was 62.3 ± 8.4 years, and the mean body mass index was 27.9 ± 5.1 kg/m2. Women comprised 55.2% of the study sample (384/696). Prevalence of cartilage damage (grade ≥2) was 47.7% (332/696) in the medial patellar and 29.9% (208/696) in patellar lateral (PL) subregions, and 24.0% (167/696) in femoral medial anterior (FMA) and 26.5% (184/696) in femoral medial central (FMC) subregions. Prevalence of osteophytes (grade ≥2) was highest at 60.8% (423/696) in the medial femoral posterior subregion, followed by 34.0% (237/696) in PL and 24.6% (171/696) in patellar medial (PM) subregions. For all other subregions, prevalence of these lesions was lower than the aforementioned percentages.
  
  
  CONCLUSIONS
  MRI-detected cartilage damage and osteophytes are highly prevalent in the medial patellofemoral and medial posterior tibiofemoral joints in radiographically normal knees in persons aged 50-79.
authors.affiliation: Department of Radiology, Boston University School of Medicine, Boston, MA 02118, USA; Department of Radiology, Bridgeport Hospital, Bridgeport, CT 06610, USA. Electronic address: dhayashi@bu.edu.
authors.forename: D
authors.initials: D
authors.lastname: Hayashi
authors.affiliation: Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: D T
authors.initials: DT
authors.lastname: Felson
authors.affiliation: Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: J
authors.initials: J
authors.lastname: Niu
authors.affiliation: Kolling Institute, University of Sydney, Sydney, NSW, Australia.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.affiliation: Department of Radiology, Boston University School of Medicine, Boston, MA 02118, USA; Department of Radiology, University of Erlangen, Erlangen, Germany.
authors.forename: F W
authors.initials: FW
authors.lastname: Roemer
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: P
authors.initials: P
authors.lastname: Aliabadi
authors.affiliation: Department of Radiology, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
mesh_terms: D000368:Aged; D015992:Body Mass Index; D042241:Early Diagnosis; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology*; D054850:Osteophyte / Q000473:pathology; D010329:Patella / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012720:Severity of Illness Index
keywords: Cartilage; Knee; Osteoarthritis; Osteophyte; Patella