Rare Classroom: Avascular Necrosis

Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The disease that we will be learning about today is:

Avascular Necrosis

Also known as osteonecrosis, bone infarction, or aseptic necrosis.

What is Avascular Necrosis?

  • Avascular necrosis is a condition of bone tissue death which occurs as a result of disruption to the blood supply
  • The femur, or thigh bone, is most commonly affected
  • Medical imaging is typically used for diagnosis, such as MRI, CT scan, or X-ray
    • Avascular necrosis can also be diagnosed via biopsy, but this is much less commonly used
  • Around 15,000 cases occur each year in the US
  • Various types of avascular necrosis have their own distinct names based on the bones that are impacted
    • Examples include:
      • Kienböck’s disease (affecting the wrist bones)
      • Mueller-Weiss syndrome (affecting the navicular bone in the foot)
      • Preiser disease (impacting the scaphoid bone)

How Do You Get It?

  • Sometimes avascular necrosis can appear with any clear cause
  • Known risk factors include:
    • High-dose steroids
    • Bone fractures
    • Joint dislocation
    • Alcohol use disorder
    • Organ transplants
    • Cancer therapies, such as radiation or chemo
  • Certain diseases and medical conditions are also associated with avascular necrosis, such as:
  • Men are more commonly affected than women

What Are the Symptoms?

  • In the early stages of the illness, no symptoms may be present and tend to develop gradually. Often, the first symptom is joint pain. Others can include:
    • Pain that progressively worsens until the patient is unable to move the affected area
    • Osteoarthritis
    • Collapse of the bone or joint surface

How Is It Treated?

  • When the femur is affected, a total hip replacement operation is a common treatment
    • These are particularly effective in older patients, but have some downsides for younger ones, as the artificial hip rarely lasts more than 20 or 30 years
    • This operation also requires a long period of recovery
  • Another therapy that can be tried is core decompression, in which internal pressure on the bone is relieved by drilling a hole into it
    • Then a chip of living bone along with an electrical device are inserted into the bone in order to trigger growth of new vasculature
    • However, the benefit of this approach isn’t clear, and more study is warranted
  • Outcomes are varied, and if a large area is affected, significant disability can result. Without treatment, arthritis and chronic pain can have major impacts of quality of life

Where Can I Learn More???

  • Check out our cornerstone on this disease here.
  • Learn more about this disease from the LFA Foundation.

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