Bone marrow edema and its relation to progression of knee osteoarthritis.
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.
Felson
David T
DT
Boston University School of Medicine, Boston, Massachusetts 02118, USA.
McLaughlin
Sara
S
Goggins
Joyce
J
LaValley
Michael P
MP
Gale
M Elon
ME
Totterman
Saara
S
Li
Wei
W
Hill
Catherine
C
Gale
Daniel
D
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