Bone marrow edema pattern in osteoarthritic knees: correlation between MR imaging and histologic findings

Area of Science:

• Orthopedics
• Radiology
• Pathology

Background:

• Osteoarthritis (OA) is a degenerative joint disease affecting millions worldwide.
• Bone marrow edema (BME) on magnetic resonance (MR) imaging is a common finding in OA knees.
• Histologic correlation of BME patterns in OA is crucial for accurate diagnosis and understanding disease mechanisms.

Purpose of the Study:

• To correlate magnetic resonance (MR) imaging findings of bone marrow edema patterns with histologic examination in osteoarthritic knees.
• To determine the specific histologic components represented by BME on MR imaging.
• To assess the diagnostic accuracy of MR imaging in identifying specific abnormalities within the BME zone.

Main Methods:

• Sixteen patients undergoing total knee replacement for OA were included.
• Sagittal short inversion time inversion-recovery (STIR) and T1/T2-weighted turbo spin-echo MR imaging were performed pre-operatively.
• Tibial plateau abnormalities on MR images were quantitatively compared with histologic maps.

Main Results:

• The BME zone on MR imaging primarily comprised normal fatty marrow (53%) and intact trabeculae (16%).
• Abnormalities within the BME zone included bone marrow necrosis (11%), abnormal trabeculae (8%), fibrosis (4%), and bleeding (2%).
• Significant differences were found in necrosis, fibrosis, and abnormal trabeculae between BME and normal MR zones, but not in edema prevalence.

Conclusions:

• A bone marrow edema pattern on MR imaging in osteoarthritic knees represents diverse, non-specific histologic abnormalities.
• Edema itself is not the predominant feature contributing to signal intensity changes observed on MR imaging in these knees.
• MR imaging findings in OA knees reflect a complex interplay of degenerative and reparative processes beyond simple inflammation.