Definition of osteonecrosis (ON)
– The occurrence of ischemic death of the cellular constituents of bone and marrow
- Avascular necrosis (AVN) : area of epiphysis or subarticular involvement
- Bone infarction : metaphyseal and diaphyseal involvement
- Double line sign
- High signal inner border with peripheral low signal on T2WI
- Inner : granulation tissue
- Outer : sclerosis
- Medullary infarction : Nutrient a. for Diaphysis
- Acute phase : No radiographic change
- BM scan : uptake ↓
- WBBS : defect (1-2D) à 이후 uptake↑
- Healing phase :
- Zone of serpiginous/linear calcification parallel to cortex
- Thin rim of sclerosis
- Dense bone indicating revascularization
- Cortical infarction
- Compromise of nutrient a. and periosteal vessel
- Acute phase : No radiographic change
Lateral radiograph of the right knee reveals large well defined serpentine regions of sclerosis in the proximal tibia and distal femur (yellow arrows). There is also be mild flattening of the tibial plateau and femoral condyle articular surfaces. This is representative of osteonecrosis of the knee, otherwise called bone infarcts.
Inflammatory response adjacent to the devascularized region
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