Bone Marrow Edema Pattern in Osteoarthritic Knees: Correlation between MR Imaging and Histologic Findings

TLDR

The study aims to correlate MR imaging of bone marrow edema patterns with histologic findings in osteoarthritic knees. Sixteen osteoarthritis patients underwent sagittal STIR and T1/T2 turbo spin‑echo MR imaging within 1–4 days before knee replacement, and tibial plateau abnormalities on MR were quantitatively compared with histologic maps. The bone marrow edema pattern zone was largely composed of normal tissue, with only a small fraction of necrosis, fibrosis, abnormal trabeculae, and edema, and edema was also present in zones with normal MR appearance, indicating that the edema pattern reflects noncharacteristic histologic abnormalities rather than a major contributor to MR signal changes.

Abstract

PURPOSE: To correlate magnetic resonance (MR) images of a bone marrow edema pattern with histologic findings in osteoarthritic knees. MATERIALS AND 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). CONCLUSION: 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.