While doctors and scientists continue to tackle the severe consequences of the continuously mutating Coronavirus, many COVID-19-related complications are being reported in different parts of the world. After the emergence of mucormycosis (black fungus), doctors have now found cases of a new condition called bone death or avascular necrosis, in COVID-19 patients. While experts continue to investigate this serious post-COVID health concern, it is believed to be a consequence of using steroids to treat severe COVID-19 infections.

What is bone death?

Bone death is a painful condition characterized by a lack of blood supply to a particular bone, resulting in the death of bone tissues. This can weaken the bone, eventually resulting in the breakdown of the bone or joint. It usually affects the long bones and joints such as the femur (thigh bone) and hip bone. Bone death is medically known as avascular necrosis, osteonecrosis, aseptic necrosis or ischemic bone necrosis. 

What causes avascular necrosis?

Avascular necrosis occurs due to reduced or interrupted blood supply to the bone. Some of the common causes of avascular necrosis include:

• Serious trauma or injury such as joint dislocation or fracture that might damage nearby blood vessels
• Long-term use of corticosteroid medications such as prednisone, cortisone or methylprednisolone
• Excessive or long-term use of alcohol
• Specific chronic medical conditions

• Fatty deposits in blood vessels
• Medical conditions that diminish the blood flow to the bone such as sickle cell anaemia and Gaucher's disease.

What are the signs and symptoms of avascular necrosis? 

In the early stages, people suffering from avascular necrosis may not develop any symptoms. As the disease progresses, they may experience certain symptoms which include:

• Joint pain, which initially occurs only when exerting weight on the affected joint and later, even while resting.
• Collapsing of the joint bone or surrounding structures.
• Reduced range of motion due to stiffness and pain.

These symptoms can also be present in any other bone-related disease. Thus, it is important to consult a doctor to get a confirmed diagnosis.

Who is at increased risk of developing avascular necrosis?

Anyone can develop avascular necrosis. However, factors that may increase the risk of developing the condition include:

• Excessive use of steroids 
• Diabetes Mellitus
• Pancreatitis (inflammation of the pancreas)
• Gaucher disease (build-up of fatty substances in the liver and spleen)
• Hyperlipidemia (high levels of fat in the blood)

• Excessive alcohol consumption

• Decompression disease (formation of gas bubbles in the body due to change in pressure)
• Blood disorders such as sickle cell anaemia, antiphospholipid antibody syndrome (APS), and lupus anticoagulant
• HIV infection 
• Radiation therapy used for cancer treatment
• Long term use of bisphosphonates
• Organ transplants (especially kidney transplants)

• Autoimmune disorders such as systemic lupus erythematosus.

How is avascular necrosis diagnosed?

After a complete analysis of the medical history of the patient and a physical exam, the doctor may prescribe specific tests to confirm the diagnosis. These tests include:

• Imaging tests: The doctor may prescribe an x-ray, a CT scan or an MRI to identify the detailed images of the affected bones. 
• Radionuclide bone scan: In this nuclear imaging technique, a small amount of radioactive material is injected into the blood. This test helps in determining the cell activity and the blood flow of the affected bone.
• Biopsy: In this procedure, a small sample of diseased tissue or bone is removed using a needle or surgically. This test helps in finding out cancerous or other abnormal cells present in the affected bone.
• Functional evaluation of bone: This surgical test helps in determining the pressure inside the bone. 

Treatment 

The treatment aims to prevent damage and improve the function of the bone or joint. The treatment of avascular necrosis includes:

1. Non-surgical treatment measures

Non-surgical treatment options are used to manage avascular necrosis in the early stages. These treatment measures include:

• Medications:
  • Nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen sodium are used to relieve the pain.
  • Osteoporosis drugs such as alendronate are used to slow the progression of avascular necrosis.
  • Cholesterol-lowering drugs such as statins are used to treat and prevent the accumulation of fat, which can cause blockage in the blood vessels.
  • Anti-coagulant (blood thinners) such as warfarin is used to prevent the formation of clots in the blood vessels that supply blood to the bones.  
• Lifestyle modifications: Restriction of all strenuous physical work and keeping weight off the affected joint. Physical therapy is provided to maintain and improve the range of motion.
• Electrical stimulation: Electrical currents are passed to the damaged bone by attaching electrodes to the skin. This current promotes new bone to grow in the place of damage.

2. Surgical treatment measures

Most people do not develop symptoms until the condition reaches an advanced stage. Thus, some patients may require surgeries to treat avascular necrosis. These surgeries include:

• Core decompression: In this surgery, the inner layer of the bone is removed to create a space that stimulates the production of healthy bone tissue and new blood vessels.
• Bone graft: In this procedure, the damaged area of the bone is replaced by a new bone (a graft), which is taken from another part of the body.
• Osteotomy: In this procedure, a portion of bone is reshaped from either above or below the weight-bearing joint. This helps in shifting the weight of the damaged bone. 
• Joint replacement: In this procedure, the completely diseased joint bone is replaced with an artificial joint made up of plastic or metal.
• Stem cell regeneration: In this procedure, the doctor removes a core of the dead bone and inserts stem cells in its place, allowing new bone to grow. Stem cells are taken from the bone marrow of the person and have the ability to grow healthy new cells.

Recommended Read: How to Keep Your Bones Strong and Healthy Naturally

Takeaway

Bone death is a painful disease that can occur due to temporary or permanent loss of blood supply to a specific bone. It can result in severe pain and disability. Scientists believe that the use of corticosteroids in the treatment of COVID-19 infection could be one of the reasons for osteonecrosis, post COVID-19 recovery. Early diagnosis and prompt treatment with medication, assistive devices or surgery can help in limiting the damage and improving the functionality of the affected bone or joint.

For any queries on bone health, you can:

Talk to an Orthopedician