AVN Flashcards
Where does AVN tend to occur at in a bone?
Epiphyseal predisposition
What is the most common etiology of AVN?
Spontaneous/idiopathic
What is the first phase of AVN?
Avascular phase
What is the main characteristic of stage 1 AVN?
Blood supply destroyed
What occurs at the epiphyseal plate during stage 1 AVN?
Growth is slowed or stopped
What happens to articular cartilage during stage 1 AVN?
Articular cartilage continues to be in place
What is the second phase of AVN?
Revascularization phase
What happens during the second phase of AVN?
New vessels form, necrotic bone is reabsorbed, new bone deposited on dead bone
What phase of AVN does creeping substitution occur in?
Stage 2 AVN
What are the characteristics of creeping substitution?
Thickened trabeculation and increased bone density
What phases of AVN can the new bone be easily modeled/deformed?
Stage 2 and Stage 3
What is the third phase of AVN?
Repair and remodeling phase
What occurs during stage 3 AVN?
Continued necrotic resorption and new deposition
What the the fourth phase of AVN?
Deformity phase
What occurs during stage 4 AVN?
Restoration of normal shape
What causes the deformity during stage 4 AVN?
Deformity is due to amount of compressive force during earlier phases
What is the crescent sign seen during?
AVN
What is the bite sign seen during?
AVN
What is the hanging rope sign seen during?
AVN
What is the mushroom deformity seen during?
AVN
What are the different radiographic sign?
- Collapse of articular cartilage
- Fragmentation
- Mottled trabecular pattern
- Bite sign
- Mushroom deformity
- Sclerosis
- Subchondral cysts
- Subchondral fractures
- Hanging rope sign
What does AVN look like on TI MRI?
Loss of signal (darker), bilateral, may have joint effusion
What is AVN in adult femoral head called?
Chandler’s Disease
What is Chandler’s Disease?
Adult femoral head AVN
What gender is more likely to have Chandler’s Disease?
Males
What age range is most likely to be affected by Chandler’s Disease?
30-70 year olds
Is Chandler’s Disease unilateral or bilateral?
Commonly bilateral
What are the early symptoms of Chandler’s Disease?
Vague symptoms early - pain in buttock, groin, thigh, knee, hip
What occurs during Chandler’s Disease over years?
Increase in pain, decrease in ROM, limping gait
What is the prognosis for Chandler’s Disease?
Better with early diagnosis and treatment, better in younger patients, better in males
Which sex has a poorer prognosis with Chandler’s Disease?
Females
What is the name of AVN in the femoral head before the growth plate closure?
Legg-Calve-Perthes disease
What Legg-Calve-Perthes Disease?
AVN in femoral head before growth plate closure
What age range is affected by Legg-Calve-Perthes disease?
4-8 year olds
What sex is affected more commonly by Legg-Calve-Perthes?
Males
What are the symptoms of Legg-Calve-Perthes?
Vague symptoms - pain in groin, limping gait, loss of ROM (abduction and internal rotation)
What is the etiology of Legg-Calve-Perthes?
Unknown
How long until Legg-Calve-Perthes resolves?
2-8 years
How long is the avascular in Legg-Calve-Perthes?
0-12 months