Osteonecrosis- Skowanska Flashcards
What are some alternative names for Osteonecrosis?
- Avascular Necrosis
- Aseptic Necrosis
- Ischemic Necrosis
What is Osteonecrosis?
Death of the bone marrow due to diminished vascular supply.
- Results in the collapse of bone architecture manifested as:
- Joint pain
- Bone destruction
- Loss of function
What are two of the leading causes of non-traumatic Osteonecrosis?
50% of cases:
- Steroids
- Alcohol abuse
Note: 40% are idiopathic cases.
What is the average age at diagnosis?
Less than 40yrs old.
What are some of the traumatic causes of Osteonecrosis?
- Femur neck fracture
- Hip dislocation
- Hip surgery
List a few of the other non-traumatic causes of Osteonec.
- Corticosteroids
- Alcohol
- SLE
- Hyperlipidemia
- HIV
- OCPs
- Radiation
- Diabetes
- Sickle Cell
- Gaucher’s
- Caisson’s disease
Describe how glucocorticoids lead to Osteonecrosis
- Venous stasis via changing venous endothelial cells. Leads to increased intraosseous pressure.
- Increased apoptosis of osteoclasts and osteoblasts
- Promote bone marrow to fat conversion
- Promote formation of microemboli from circulating lipids- occlusion.
- Directly killing Osteocytes
Describe the stepwise pathogenesis of Osteonecrosis
- Compromised blood flow –> leads to disappearance of osteocytes and marrow fat necrosis.
- Infarction causes marrow edema –> Leads to venous outflow obstruction.
- Outflow obstruction leads to increased pressure –> results in widened area of Infarction.
- Hyperemia of surrounding areas results in osteoporosis of living bone; infarcted bone will appear hyper dense on imaging.
- The bone is revascularized, increasing the likelihood of resorption and mechanical failure –> subcondral fracture (crescent sign)
- Femoral head flattening can occur and progression of secondary osteoarthritis.
What are the clinical manifestations of Osteonecrosis?
- Sudden onset of pain
- Pain with movement –> Pain at rest
- Night pains are common
- Impaired ROM
Where is the most common site for AVN?
- Femur head
- Due to reduced blood supply at specific location in femur head.
-Ischemia will manifest as Hip pain radiating to groin, medial aspect of knee, and buttocks.
Describe the Radiologic findings of AVN
- Initially normal
- Hyperdensity of Necrotic bone (collapse of necrotic bone into a smaller segment produces a hyperdense appearance.)
- Mottled bone densities produced by combination of necrotic and new bone formation.
What is a hallmark X ray finding of necrotic bone at the femur head?
Crescent sign
There are stages 0 to 4 in Osteonecrosis. Which one do we see the Crescent sign?
Stage III.
Describe the treatment of Osteonecrosis
- Stage Development
- Conservative Palliation (Analgesics)
- Reduce steroid and alcohol use
- If EARLY aseptic necrosis present (with no Xray changes), surgical core decompression and osteotomy needed.
- If Late aseptic necrosis present (with Xray changes) associated with damaged bone or joint, Bone/Joint replacement needed
-Bisphosphonates
