title: Bone marrow edema and its relation to progression of knee osteoarthritis.
abstract: BACKGROUND
  While factors affecting the course of knee osteoarthritis are mostly unknown, lesions on bone scan and mechanical malalignment increase risk for radiographic deterioration. Bone marrow edema lesions on magnetic resonance imaging correspond to bone scan lesions.
  
  
  OBJECTIVE
  To determine whether edema lesions in the subarticular bone in patients with knee osteoarthritis identify knees at high risk for radiographic progression and whether these lesions are associated with limb malalignment.
  
  
  METHODS
  Natural history study.
  
  
  METHODS
  A Veterans Administration hospital in Boston, Massachusetts.
  
  
  METHODS
  Persons 45 years of age and older with symptomatic knee osteoarthritis.
  
  
  METHODS
  Baseline assessments included magnetic resonance imaging of the knee and fluoroscopically positioned radiography. During follow-up at 15 and 30 months, patients underwent repeated radiography; at 15 months, long-limb films were obtained to assess mechanical alignment. Progression was defined as an increase over follow-up in medial or lateral joint space narrowing, based on a semi-quantitative grading. Generalized estimating equations were used to evaluate the relation of medial bone marrow edema lesions to medial progression and lateral lesions to lateral progression, before and after adjustment for limb alignment.
  
  
  RESULTS
  Of 256 patients, 223 (87.1%) participated in at least one follow-up examination. Medial bone marrow lesions were seen mostly in patients with varus limbs, and lateral lesions were seen mostly in those with valgus limbs. Twenty-seven of 75 knees with medial lesions (36.0%) showed medial progression versus 12 of 148 knees without lesions (8.1%) (odds ratio for progression, 6.5 [95% CI, 3.0 to 14.0]). Approximately 69% of knees that progressed medially had medial lesions, and lateral lesions conferred a marked risk for lateral progression. These increased risks were attenuated by 37% to 53% after adjustment for limb alignment.
  
  
  CONCLUSIONS
  Bone marrow edema is a potent risk factor for structural deterioration in knee osteoarthritis, and its relation to progression is explained in part by its association with limb alignment.
authors.affiliation: Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Felson
authors.forename: Sara
authors.initials: S
authors.lastname: McLaughlin
authors.forename: Joyce
authors.initials: J
authors.lastname: Goggins
authors.forename: Michael P
authors.initials: MP
authors.lastname: LaValley
authors.forename: M Elon
authors.initials: ME
authors.lastname: Gale
authors.forename: Saara
authors.initials: S
authors.lastname: Totterman
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Catherine
authors.initials: C
authors.lastname: Hill
authors.forename: Daniel
authors.initials: D
authors.lastname: Gale
mesh_terms: D000368:Aged; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology*; D018450:Disease Progression; D004487:Edema / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012307:Risk Factors