(Fig 5-B.35) Patterns of Subchondral Bone Plate Fracture in Osteonecrosis

https://youtu.be/zwQFgPL9ErM

https://youtu.be/9qehWGE9dp4

👉 Click the link below and request access—I’ll approve it for you shortly!
https://www.notion.so/MSKMRI-KNEE-b6cbb1e1bc4741b681ecf6a40159a531?pvs=4
==============================================

✨ Join the channel to enjoy the benefits! 🚀
https://www.youtube.com/channel/UC4bw7o0l2rhxn1GJZGDmT9w/join
==============================================

👉 "Click the link to purchase on Amazon 🎉📚"
[Visualizing MSK Radiology: A Practical Guide to Radiology Mastery]
https://www.amazon.com/dp/B0DJGMHMFS
==============================================

MSK MRI Jee Eun Lee

Visualizing MSK Radiology: A Practical Guide to Radiology Mastery

👉 Click the link below and request access

📌 Fracture of the Subchondral Bone Plate in Osteonecrosis

✅ Epiphyseal Collapse

• Epiphyseal collapse in osteonecrosis is characterized by a deformity of the subchondral bone or a fluid-filled cleft, or both. 
• This condition is better visualized on radiographs or CT images, likely due to the higher spatial resolution they provide 

 

✅ MRI Patterns of Subchondral Bone Plate Fracture

The fracture of the subchondral bone plate can present two patterns on MRI:

• Depression of the subchondral bone plate: This pattern shows a loss of epiphyseal contour 
• High-signal-intensity line on T2-weighted MR images: More rarely seen in the knee, this pattern represents fluid accumulating in the subchondral fracture cleft, extending under the subchondral bone plate 

 

✅ Changes in Signal After Articular Collapse

• Following articular collapse, the signal in the necrotic segment changes due to fragmentation, invasion of fibrovascular tissue, and secondary cyst formation. 
• The normal fatty signal intensity on T1-weighted images is lost, replaced with inhomogeneous low to intermediate signal intensity, especially in the weight-bearing area of the infarct 

 

✅ Factors Contributing to Collapse

Several factors contribute to the development of a collapse:

• Fatigue microfractures: The cumulative effect of these fractures in the necrotic zone.
• Osteoclastic activity: This activity causes weakening of the trabeculae in the reparative front.
• Mechanical stress: Focal concentration of mechanical stress on thickened bone trabeculae in the reparative zone along the AVN margins acts as “stress risers” 

 

✅  Risk Factors for Collapse in the Femoral Condyle

• The risk of collapse in the femoral condyle is directly related to the size and location of the infarct. 
• Lesions involving more than one-third of the condyle on midcoronal MR images or the middle and posterior one-third of the condyle on midsagittal MR images are at higher risk of collapse. 
• Collapse begins at the lateral boundary of the necrotic lesion and, depending on the lesion's size, propagates either along the subchondral region or in the deep necrotic region 

 

References

• AJR 2019; 213:963–982
• RadioGraphics 2018; 38:1478–1495

 

"Visualizing MSK Radiology: A Practical Guide to Radiology Mastery"

© 2022 MSK MRI Jee Eun Lee All Rights Reserved.

No unauthorized reproduction, redistribution, or use for AI training.

#Osteonecrosis, #SubchondralBone, #EpiphysealCollapse, #MRI, #Radiology, #BoneFracture, #FemoralCondyle, #ArticularCollapse, #MedicalImaging, #Orthopedics