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• Credits

  • Section Writer: Dr. Om J Lakhani
  • Section Editor: Dr. Om J Lakhani

• Linked notes:

  • Glucocorticoid induced osteoporosis (GIO)
  • Exogenous Cushing syndrome (Iatrogenic Cushing syndrome)
  • Major side effects of systemic glucocorticoids

• Q. What are the other terms used for Osteonecrosis?

  • aseptic necrosis
  • avascular necrosis (AVN)
  • atraumatic necrosis
  • ischemic necrosis

• Q. What is osteonecrosis?

  • Any process that interferes with the vascular supply of the bones produces ischemia and eventual necrosis. This is osteonecrosis.

• Q. Enlist the causes of osteonecrosis.

  • Fracture of femur neck (traumatic)
  • Non-traumatic
    • Corticosteroids
    • SLE
    • Alcoholic
    • Pancreatitis
    • Sickle cell
    • HIV
    • Radiation
    • Chronic kidney disease
    • Transplantation
    • Decompression illness
    • APLA syndrome

• Q. What are the possible etiologies of glucocorticoid-induced osteonecrosis?

  • Changes in venous endothelial cells → blocking of veins
  • Alteration of fat à production of microemboli → ischemic necrosis
  • Increase of bone marrow fat → blocking of venous circulation

• Q. Which is more important for the causation of osteonecrosis- dose or duration of glucocorticoid?

  • Duration- typically osteonecrosis occurs with a long duration of therapy
  • It can occur with any dose of medication, even low doses used in physiological replacement can cause osteonecrosis

• Q. Which medication used in the treatment of osteoporosis is associated with osteonecrosis?

  • Bisphosphonate especially when used in the context of malignancy like multiple myeloma etc
  • It is generally associated with osteonecrosis of the jaw
  • Similar features may also be seen with Denosumab

• **CLINICAL FEATURES  **

• Q. Which is the most common site of osteonecrosis?

  • Anterolateral aspect of the femoral head

• Q. What is the most common clinical manifestation?

  • Pain is the most common manifestation

• Q. Can it be asymptomatic?

  • Yes

• Q. What kind of X-rays are ordered to make the diagnosis?

  • AP, Lateral, and frog-leg position for pelvis and hip

• Q. What is the classical sign seen in Xray?

  • "Crescent sign"
  • However, it occurs late only when joint collapse occurs
  • 

• Q. What is the role of a bone scan in this condition?

  • Area of increased uptake in the junction of dead and alive tissue with a central cold area is seen on a bone scan
  • This is a classical "doughnut sign"
  • 

• Q. What is the best imaging modality for osteonecrosis?

  • MRI – 100% sensitivity
  • High-intensity lines in MRI are typical
  • It is the gold standard in the diagnosis of this lesion

• Q. What is the pathological classification system for the disease?

  • Type I- prenecrotic
  • Type II- medullary space filled with necrotic tissue
  • Type III- marrow necrosis
  • Type IV- complete necrosis

• Q. What are the clinical stages of this lesion?

  • Stage 0 - diagnostic studies normal and diagnosis by histology only
  • Stage 1 - Plain radiographs and CT normal, MRI positive, and biopsy positive, with the extent of involvement A, B or C (less than 15 percent, 15 to 30 percent, and greater than 30 percent, respectively)
  • Stage 2- Radiographs positive but no collapse (no crescent sign), with the extent of involvement A, B, or C
  • Stage 3 - Early flattening of the dome and/or crescent sign on plain radiography or by CT or tomograms, with the extent of involvement A, B, or C and further characterization by the amount of depression (in millimeters)
  • Stage 4 Flattening of the femoral head with joint space narrowing on plain radiography, as well as other signs of osteoarthritis

• **Treatment **

• Q. What are the treatment options?

  • Non-operative
  • Joint preserving surgery
  • Joint replacement

• Q. Is a non-operative strategy effective?

  • Non-operative interventions include medications, non-weight bearing, and rest
  • They are effective only in 20% of cases

• Q. Can bisphosphonate be used in the treatment of osteonecrosis?

  • Bisphosphonate in the treatment of osteonecrosis has shown mixed results

• Q. Which are other pharmacological agents used in the treatment of osteonecrosis?

  • Iloprost
  • Anticoagulants
  • Statins

• Q. Which are the various joint preserving procedures?

  • Fibular grafting
  • Decompression
  • Osteotomy

• #Real-life-cases

  • This is the MRI of a patient with Avascular necrosis of the femoral head
  • The patient had Exogenous Cushing's syndrome due to treatment from a local quack
  • He came in a Septic shock and was diagnosed to have tertiary adrenal insufficiency
  • 

#update

• December 9th, 2022
• Q. Is there a role of Teriperatide in Avascular necrosis?
  • Yes
  • A study compared teriparatide to alendronate and found it to be more efficacious for preventing collapse compared to alendronate
  • The mean duration of therapy was 18 months ^[1]
• Q. What does Teriperatide prevent in these cases ?
  • They prevent the collapse of the femoral head
• Q. How common is the collapse of the femoral head?
  • It occurs in 75-80% of cases within 3-4 years
  • It produces severe pain
  • Most cases would need a total hip replacement in case of complete collapse

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