Bone marrow edema pattern in osteoarthritic knees: correlation between MR imaging and histologic findings.
OBJECTIVE
To correlate magnetic resonance (MR) images of a bone marrow edema pattern with histologic findings in osteoarthritic knees.


METHODS
Sixteen consecutive patients (age range, 43-79 years; mean, 67 years) referred for total knee replacement were examined with sagittal short inversion time inversion-recovery (STIR) and T1- and T2-weighted turbo spin-echo MR imaging 1-4 days before surgery. Tibial plateau abnormalities on MR images were compared quantitatively with those on histologic maps.


RESULTS
The bone marrow edema pattern zone (ill-defined and hyperintense on STIR images and hypointense on T1-weighted MR images) mainly consisted of normal tissue (53% of the area was fatty marrow, 16% was intact trabeculae, and 2% was blood vessels) and a smaller proportion of several abnormalities (bone marrow necrosis [11% of area], abnormal [necrotic or remodeled] trabeculae [8%], bone marrow fibrosis [4%], bone marrow edema [4%], and bone marrow bleeding [2%]). The bone marrow edema pattern zone and the zone with a normal MR imaging appearance differed significantly in the presence of bone marrow necrosis (P =.021), bone marrow fibrosis (P =.014), and abnormal trabeculae (P =.011) but not in the prevalence of bone marrow edema (P =.069). Bone marrow edema also was found in zones with an unremarkable MR appearance (perifocal zone, 5% edema; control zone, 2% edema).


CONCLUSIONS
A bone marrow edema pattern in osteoarthritic knees represents a number of noncharacteristic histologic abnormalities. Edema is not a major constituent of MR imaging signal intensity abnormalities in such knees.
Zanetti
M
M
Department of Radiology, Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland. mzanetti@balgrist.unizh.ch
Bruder
E
E
Romero
J
J
Hodler
J
J
D000328:Adult; D000368:Aged; D001853:Bone Marrow / Q000473:pathology; D001855:Bone Marrow Diseases / Q000175:diagnosis* / Q000473:pathology; D004487:Edema / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000473:pathology; D013997:Time Factors