Avascular Necrosis of Bone: Overview

Avascular Necrosis Summary

Avascular Necrosis Summary

  1. Avascular necrosis is the death of bone tissue due to a lack of blood supply, often leading to bone collapse.
  2. Common causes include trauma, steroid use, or excessive alcohol consumption.
  3. Early symptoms include joint pain, with advanced stages causing limited movement and severe joint damage.

Introduction

Avascular necrosis (AVN), called osteonecrosis too, is a condition where bone tissue dies because blood supply is not enough.

When blood flow to the bone lessens or stops, the tissue weakens and collapses, which can affect joint function. The hip joint is the most commonly impacted but it can also affect joints like the shoulder, knee, ankle, and elbow.

This condition often causes pain and limits movement, leading to potential joint damage that may need surgery, like joint replacement.

Causes

The main cause of avascular necrosis is the stopping of the blood flow to the bone, leading to the death of bone cells.

Blood vessels that bring oxygen and nutrients to the bone can get blocked or narrowed, resulting in ischemia (no blood flow) and bone death.

There are several known causes of AVN, split into traumatic and non-traumatic factors.

1. Traumatic Causes:

Fractures +
A fracture, especially one that affects the blood vessels to the bone, can cause AVN. Hip fractures, particularly femoral neck fractures, often lead to AVN by damaging blood supply to the femoral head.
Dislocations +
A dislocated joint, notably in the hip or shoulder, can harm the blood vessels to the bone, leading to AVN if those vessels are affected.

2. Non-Traumatic Causes:

Steroid Use +
Long-term corticosteroid use, especially at high doses, is a common non-traumatic cause of AVN. Steroids can contribute to fat buildup in blood vessels, leading to damage and less blood flow to bones.
Alcohol Abuse +
Heavy alcohol use over time is another recognized cause of AVN. Alcohol can affect blood flow by causing fat globules in the blood and damaging blood vessels, leading to bone tissue death.
Blood Disorders +
Diseases like sickle cell anemia and hemophilia can lead to blockages in small blood vessels, reducing blood supply to bones and causing AVN.
Radiation Therapy +
Radiation, especially for treating cancers near bones, can damage blood vessels and reduce blood supply to bones, raising the risk of AVN.
Lupus and Other Autoimmune Diseases +
Certain autoimmune diseases, like systemic lupus erythematosus (SLE), may increase AVN risk due to the condition itself and the treatments (like steroids) used.
Decompression Sickness +
Often seen in divers, this occurs when bubbles form in blood vessels and block blood flow, leading to AVN.
Hyperlipidemia +
High cholesterol and fat buildup in blood vessels can lead to AVN by affecting blood circulation to the bone.

Symptoms

The symptoms of avascular necrosis usually develop slowly and differ based on the bone involved and the stage of the disease.

The common symptoms are:

  1. Pain: Pain is the most frequent symptom of AVN. It usually starts dull and intermittent but may get more severe and constant. It often worsens with weight-bearing activities or movement, located in the joint or bone. In cases of hip AVN, pain is often felt. in the groin or thigh and may spread to the knee.
  2. Stiffness: As the condition worsens, joint stiffness can happen, causing trouble with joint movement. Pain or bone collapse might significantly reduce the range of motion.
  3. Weakness: AVN may weaken the bone in question, making the joint unstable. This increases the risk of fractures, worsening the condition.
  4. Swelling: Sometimes, swelling can occur around the joint, especially with inflammation or injury to nearby tissues.
  5. Functional Impairment: In later stages, bone collapse can lead to joint deformities, resulting in functional issues. Those with advanced AVN might struggle to walk, climb stairs, or do activities needing joint movement.
  6. Other Symptoms: AVN can also result in muscle loss and tiredness, particularly if the person limits physical activity due to pain or discomfort.

Risk Factors

Several factors can increase the risk of getting avascular necrosis, such as:

  1. Trauma and Injury: Direct injury to bones, including fractures or dislocations, raises the chance of AVN. This is especially true for fractures in the femoral neck or acetabulum, as they are vital for blood flow to the femoral head in the hip.
  2. Steroid Use: Long-term corticosteroid use is a significant risk factor for AVN, especially if high doses are taken for a long time. This is thought to involve fat buildup in blood vessels and reduced blood flow to bones.
  3. Alcohol Consumption: Long-term alcohol abuse is a notable risk factor, as it can lead to fat emboli formation and blood vessel damage, disrupting oxygen and nutrient supply to the bone.
  4. Blood Disorders: Conditions like sickle cell anemia or hemophilia, which affect blood flow, can significantly heighten the risk of developing AVN. Any condition impacting blood circulation can limit oxygen supply to bone tissues.
  5. Age: AVN is more frequent in people aged 30 to 50, but it can affect anyone. It’s rare in children, but adolescents with certain risk factors may experience it.
  6. Chronic Health Conditions: Autoimmune diseases like lupus and health issues such as diabetes and high cholesterol can increase AVN risk due to their impact on blood vessels and circulation.
  7. Radiation Exposure: Previous radiation therapy close to bones, often used for treating cancer, can raise the risk of AVN by harming blood vessels and bone tissue.

Differential Diagnosis

Several other conditions can mimic avascular necrosis symptoms, making it necessary to distinguish AVN from other joint or muscle disorders.

Differential diagnoses include:

1. Osteoarthritis +
Osteoarthritis is a degenerative joint issue that causes pain, stiffness, and less mobility, similar to AVN. However, osteoarthritis usually results from long-term wear and tear, while AVN stems from poor blood supply to the bone.
2. Rheumatoid Arthritis +
This autoimmune disease leads to joint inflammation and can cause joint damage, including pain and swelling. Unlike AVN, rheumatoid arthritis features general inflammation and often impacts multiple joints.
3. Infection +
Bone infections (osteomyelitis) can lead to pain, swelling, and limited function. Generally, infections also involve fever and signs of systemic illness, which aren’t present in AVN.
4. Fractures +
Fractures, particularly in the hip or knee, can result in pain and restricted movement similar to AVN. Imaging studies can confirm fractures, showing a break in the bone, unlike AVN, which involves bone death without a break.
5. Bone Tumors +
Primary bone tumors or metastases to bone can lead to discomfort, swelling, and deformities. To distinguish between AVN and bone cancer, a biopsy alongside imaging methods like MRI or CT scans is necessary.

Investigation

To confirm a diagnosis of avascular necrosis, a mixture of clinical evaluation, imaging tests, and sometimes a biopsy is used. Common diagnostic techniques include:

  1. X-ray Imaging: X-rays are typically the first imaging technique for examining bone structure. Early AVN may not show on X-rays, but later on, they can show issues like bone collapse, narrowed joint space, and sclerosis.
  2. MRI (Magnetic Resonance Imaging): MRI is the most sensitive tool for spotting early-stage AVN. It can detect bone marrow swelling, which signals AVN before any collapse happens.
  3. CT Scan (Computed Tomography): A CT scan evaluates how severe the bone damage is and checks for bone collapse or fractures. It provides detailed 3D images to assess AVN severity.
  4. Bone Scintigraphy: Bone scans help find areas of abnormal bone activity, identifying zones with low blood flow or early AVN symptoms.
  5. Biopsy: In rare instances, a biopsy might be done on the affected bone to verify the diagnosis, especially if it’s unclear or if there’s suspicion of cancer.

Treatment

Treating avascular necrosis varies based on disease stage, bone damage extent, and affected joints. Key treatment goals include pain relief, joint function preservation, and halting disease progression. Management spans conservative approaches to surgery, influenced by severity and stage.

1. Conservative Treatments:

Pain Management: Controlling pain is vital in early AVN stages. Nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen or acetaminophen, may help with pain and inflammation but require monitoring due to potential side effects.

Rest and Activity Modification: Resting the affected joint and avoiding activities that stress the bone is necessary. Physical therapy might be suggested to maintain joint flexibility and strength without overexertion.

Bisphosphonates: These drugs, often for osteoporosis, may help slow AVN progression in early cases by preventing bone loss and promoting healing.

Electrical Stimulation: In some cases, electrical stimulation may be applied to encourage healing. This is usually for patients with early AVN aiming to avoid surgery.

2. Surgical Treatments:

Core Decompression: A common procedure for early AVN, it involves removing a small bone portion to ease pressure and enhance blood flow. This surgery seeks to slow bone death and maintain joint function, working best when done early before major collapse.

Osteotomy: If AVN causes joint deformity or misalignment, osteotomy may be needed. This realigns the bone to reduce pressure, especially in the hip or knee, improving function and reducing pain.

Bone Grafting: This may accompany core decompression to promote healing, involving the transplantation of bone tissue to replace damaged areas. It’s used for larger damage areas.

Total Joint: Replacement: In serious cases of avascular necrosis (AVN), where there is joint collapse and serious arthritis, surgery to replace the joint might be needed. Total hip replacement (THR) and total knee replacement (TKR) are the usual surgeries for patients with final-stage AVN. Joint replacement could help ease pain, bring back function, and raise quality of life. But, it’s important to know that joint replacement does not cure AVN, and people may need more surgeries after some years.

Stem Cell Therapy and Regenerative Medicine: Studies on treatments like stem cell therapy and platelet-rich plasma (PRP) injections are in progress. These methods target tissue healing and aim to fix injured bone. Although early tests show good results, these therapies are not yet commonly applied in the treatment of AVN.

4. Post-Surgical Rehabilitation:

After surgery, patients will partake in rehab to boost strength, range of motion, and overall function.

Physical therapy will concentrate on slowly boosting activity, strengthening the supporting muscles, and enhancing joint flexibility.

Rehab is a vital part of recovery, especially following joint replacement or core decompression surgery.

5. Management of Risk Factors:

Managing risk factors, such as alcohol misuse, long-term corticosteroid use, and blood disorders, is crucial to avert more bone harm in AVN. For example:

Alcohol Abstinence: Those who drink heavily should be encouraged to stop to lower AVN risk.

Corticosteroid Management: Patients who need steroids for an extended period must be monitored closely to potentially lower AVN risks. Doctors might look into other medicines or methods to handle conditions needing steroids.

Treatment of Blood Disorders: People with blood issues like sickle cell disease should consider treatment methods that enhance blood flow and lessen clotting risks to help prevent AVN from worsening.

Prognosis:

The outcome of AVN varies based on factors such as disease stage at diagnosis, which joint is affected, and the treatment used. Early diagnosis and timely action are vital to halt AVN progression and keep joint function intact.

  • Early-Stage AVN: If spotted early, conservative measures like pain relief, changing activity levels, and core decompression can avoid more serious operations and maintain joint function. Patients who follow treatment suggestions and adapt their lifestyle can often keep joints functional for many years.
  • Advanced AVN: In later stages, with joint damage and arthritis, surgeries like joint replacement become necessary. Although joint replacement can greatly enhance quality of life and relieve pain, it won’t cure AVN and may require follow-up surgeries. Managing joint health is needed even post-surgery.
  • Complications: Without treatment, AVN can cause long-term pain, joint dysfunction, and permanent disability. In severe situations, patients may face total joint destruction, resulting in a lower quality of life and possible reliance on assistive devices such as walkers or wheelchairs. For those with systemic issues that make them prone to AVN, ongoing management of the primary condition is crucial to avoid further problems.

Conclusion

Avascular necrosis of bone is a serious issue leading to bone death and joint problems due to inadequate blood flow.

It can affect any bone, but the hip joint is the most commonly impacted, leading to pain, stiffness, and limited movement.

The reasons for AVN vary, from trauma and fractures to factors like steroid use, alcohol abuse, and specific blood disorders. Quick diagnosis and intervention are essential. are important in handling the situation and stopping joint failure.

References Box
References +
  • Mont, M. A., & Marker, D. R. (2014). “Avascular necrosis of the femoral head: pathogenesis and treatment.” The Journal of Bone and Joint Surgery, 96(1), 1-12.
  • Scully, S. P., & Simon, M. A. (1993). “Avascular necrosis of bone: pathogenesis, diagnosis, and treatment.” Orthopedic Clinics of North America, 24(2), 345-367.
  • Koo, S. S., & Lim, H. C. (2009). “Avascular necrosis of the femoral head: a review of the pathophysiology and treatment.” Clinics in Orthopedic Surgery, 1(1), 7-16.
  • Kline, A. J., & Haspel, E. A. (2016). “Current management strategies for avascular necrosis of the hip.” Orthopedics, 39(3), 162-171.
  • Ficke, J. R., & Bice, M. (2013). “Avascular necrosis: current treatment options.” Journal of the American Academy of Orthopaedic Surgeons, 21(10), 586-594.
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