Avascular Necrosis of Hip- Osteonecrosis

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Avascular Necrosis of Hip

Avascular necrosis (AVN), also known as osteonecrosis, is a condition characterized by the death of the bone tissue due to a lack of blood supply. The condolence most commonly affects the hip joint, causing severe pain and disability. 

The hip joint is a ball-and-socket joint where the ball, or femoral head (head of the thigh bone), fits into the socket of the pelvic bone. When the blood supply to the femoral head is interrupted, the bone tissue begins to die, which can eventually lead to the collapse of the hip joint if not treated on time.

What are the causes of AVN of the hip?

Avascular necrosis develops due to an interruption of blood flow to the bone. This could occur due to the following reasons:

• Trauma leading to hip fracture or dislocation ( Know more about- What is Bone Fracture ? )
• Long-term use of steroids 
• Excessive alcohol consumption 
• Certain medical conditions like lupus (an autoimmune disease that could lead to inflammation and blood vessel damage), sickle cell anemia (abnormal red blood cells that could block the blood flow), and Gaucher’s disease (a genetic disorder that could affect lipid metabolism and lead to the accumulation of fatty substances)
• Decompression sickness (a condition usually seen in divers or pilots due to rapid changes in pressure which causes the formation of nitrogen bubbles in the blood, ultimately leading to the blockage of blood vessels)
• Idiopathic (unknown cause)

What are the risk factors for AVN of hip?

Certain factors can increase the likelihood of developing avascular necrosis of the hip. These risk factors include:

• Hip injuries, fractures, or dislocations
• Chronic use of high-dose corticosteroids to treat conditions like asthma, autoimmune diseases, and treatment after organ transplantation 
• Excessive consumption of alcohol 
• Presence of certain medical conditions like lupus, sickle cell disease, Gaucher’s disease, diabetes, HIV, or AIDS
• Patients undergoing organ transplant 
• Radiation therapy for cancer treatment 
• Pilots and divers
• Blood clotting disorders

What are the symptoms of AVN of hip?

The common symptoms associated with avascular necrosis of hip are:

• Pain in the groin, buttock, or thigh area
• Limited hip joint mobility and stiffness
• Limping

How to diagnose AVN of hip?

The following tests can help in diagnosing avascular necrosis of hip:

• Physical examination: The doctor will check for tenderness, range of motion, and any signs of joint instability or deformity.
• Imaging tests: These tests are done to obtain images of the internal parts of the body and may include the following:

• X-rays: Initial X-rays may appear normal in the early stages of avascular necrosis. However, as the disease progresses, X-rays can reveal changes in bone structure and hip joint collapse.
• MRI scan: Magnetic resonance imaging or MRI scan is the most sensitive method for detecting avascular necrosis in its early stages. It can show bone marrow changes and areas of reduced blood supply before these changes appear on X-rays.
• Bone scan: This test can help in detecting changes in blood flow to the bone, although it is less specific than an MRI.

Stages of avascular necrosis:

Avascular necrosis of the hip is classified into four stages depending on the extent of bone damage, as determined by the diagnostic test results. The four stages are:

• Stage I: Early avascular necrosis with no visible changes on X-rays, but abnormalities seen on MRI or bone scan.
• Stage II: Evidence of bone hardening (sclerosis) or small areas of bone collapse.
• Stage III: Partial collapse of the femoral head with a crescent sign (a specific radiographic finding).
• Stage IV: Advanced collapse of the femoral head and secondary arthritis in the hip joint.

How is AVN of hip treated?

The treatment of avascular necrosis of the hip aims to preserve the femoral head and hip joint function. The type of treatment done depends on the stage of the disease and the patient’s overall health. The different treatment options include the following:

Non-surgical treatments: The non-surgical treatment options are:

Medications: The different medications that may be recommended include the following:

• Bisphosphonates: These medications can help prevent bone loss and reduce the risk of femoral head collapse.
• Blood thinners: In some cases, blood thinners may be prescribed to improve blood flow to the affected area.
• Pain relievers: Nonsteroidal anti-inflammatory drugs (NSAIDs) can help manage pain and inflammation.

Physical therapy: Exercises aimed at maintaining joint mobility and strengthening the muscles around the hip can be beneficial. Weight-bearing activities should be minimized to reduce stress on the joint.

Assistive devices: The use of crutches or a cane can help reduce the weight from the affected hip, thus decreasing pain and preventing further damage.

Surgical treatments: When non-surgical treatments fail to relieve the symptoms or if the disease has progressed to advanced stages, surgical intervention may be necessary. The different surgical treatment options are:

Core decompression: This procedure involves removing a portion of the inner bone to reduce pressure and create channels for new blood vessels to nourish the affected area. It is most effective in the early stages of avascular necrosis.

Osteotomy: This surgical procedure involves reshaping the bone to reduce stress on the affected area. It is usually considered for younger patients with localized bone damage.

Bone grafting: Healthy bone tissue from another part of the body or a donor is transplanted to the affected area to support bone regeneration.

Total hip replacement: In advanced cases, where the femoral head has collapsed and there is significant joint damage, total hip arthroplasty (replacement) may be recommended. This procedure involves replacing the damaged hip joint with an artificial implant. ( Know more about- Cost of Hip Replacement Surgery in Bangalore )

What are the risks of AVN of the hip?

If avascular necrosis of hip is left untreated, it may lead to the following complications:

• Femoral head collapse
• Severe arthritis in the hip joint leading to a disability 
• Joint deformity
• Persistent pain
• Reduced mobility
• Secondary osteoarthritis
• Depression, anxiety, or other mental health problems 

Surgical treatment to treat avascular necrosis may be associated with the following risks:

• Infection 
• Bleeding 
• Blood clot formation 
• Allergic reaction to anesthesia 
• Implant loosening or wear over time in case of a hip replacement surgery 
• Risk of recurrence after treatment 

We hope that we were able to answer all your questions about avascular necrosis of hip through this article.

If you want more information about avascular necrosis of the hip, you can contact a good orthopedic surgeon in the best hospitals like Manipal Hospital Whitefield. 

We only aim to give you information through the article and do not recommend any medication or treatment in any way. Only a qualified doctor can give you good advice because no one else is better than them.