What is avascular necrosis?
Avascular necrosis (AVN) is the death of bone tissue due to loss of blood supply. You may also hear it called osteonecrosis, aseptic necrosis, or ischemic bone necrosis. If left untreated, AVN can cause the bone to collapse. Avascular necrosis most often affects your hip. Other common sites are the shoulders, knees, and ankles.
Symptoms of avascular necrosis
The hip bone is the joint most commonly affected with avascular necrosis. AVN also commonly affects the knee. Less commonly, AVN affects the bones in these areas:
In its early phases, AVN may not cause symptoms. As blood cells die and the disease progresses, symptoms may appear roughly in this order:
- Mild or severe pain in or about the affected joint
- Pain in the groin that extends to the knee
- Pain that occurs when weight is placed on the hip or knee
- Joint pain severe enough to limit movement
The pain can dramatically increase in intensity due to small breaks in the bone, called microfractures. These can cause the bone to collapse. Ultimately, the joint can break and develop arthritis. The time between the first symptoms and the inability to move a joint varies.
In general, it varies from a few months to more than a year. Symptoms can appear bilaterally, that is, on both sides of the body. If avascular necrosis grows in the jaw, symptoms comprise exposed bone in the jaw bone with pain or pus, or both.
Causes of avascular necrosis
Although the precise mechanism for the development of avascular necrosis is unknown, it is suspected that interruption of the blood supply to the affected bone plays a role. This can occur when a traumatic impact injures the blood vessels of the bone or when diseases produce areas of abnormal circulation.
There are many causes of avascular necrosis, but the vast majority of avascular necrosis is caused by traumatic injury to the affected bone (such as fracture and dislocation), the use of steroid medications (glucocorticoid medications such as prednisone and prednisolone, particularly when administered in high doses). dose), or excessive alcohol consumption.
Other risk factors for developing avascular necrosis include cigarette smoking, pregnancy, radiation and chemotherapy treatments, diseases of the bone marrow and blood (including sickle cell disease, leukemia, Gaucher disease, thalassemia), and diver’s disease. underwater (from the bone effects of Caisson’s disease, too). known as dysbarism or “the curves”). Avascular necrosis occurs more frequently in patients with certain underlying diseases, such as systemic lupus erythematosus, diabetes mellitus, vasculitis, and inflammatory bowel disease.
Currently, some researchers suspect that intravenous bisphosphonate medications, including zoledronate (Zometa) and pamidronate (Aredia), are used to reduce elevated calcium levels in cancer patients and to treat osteoporosis, which may grow the risk of avascular necrosis of the chin and bone. Ironically, some use bisphosphonates to treat bone pain and decrease disability in patients with avascular necrosis.
Risk factors of avascular necrosis
Risk factors include:
- Use of steroids
- Gaucher disease
- Caisson disease
- Alcohol consumption
- Blood disorders, such as sickle cell anemia
- Radiation treatments
- Decompression sickness
- Hypercoagulable state
- Autoimmune disease
Diagnosis of avascular necrosis
- An X-ray is usually the first test done when AVN is suspected. It can help distinguish AVN from other causes of bone pain, such as a fracture. Once the diagnosis is made, and in the latter stages of AVN, X-rays are helpful in monitoring the course of the condition.
- MRI is sometimes used to diagnose AVN because it can detect AVN in the early stages when symptoms are not yet present.
- Bone scans can also be used to diagnose AVN. They are helpful because a scan can show all areas of the body affected by AVN. However, bone scans do not detect AVN in the early stages.
- A CT scan provides a three-dimensional image of the bone and can be helpful in determining the extent of bone damage.
- Surgical procedures, such as a bone biopsy, can conclusively diagnose VAP but are not often performed.
Treatment for avascular necrosis
Treatment will be contingent on your symptoms, age, and overall health. It will also be contingent on the severity of the condition. The goal of treatment is to improve your ability to use the joint and stop further damage to the bone or joint. Treatments are needed to prevent the joints from breaking. They may include:
- Medicines: They are used to control pain.
- Assistive devices: They are used to reduce weight on the bone or joint.
- Core decompression: For this surgery, the inner layer of bone is removed to reduce pressure, increase blood flow, and slow or stop the destruction of bones and joints.
- Osteotomy: This procedure reshapes the bone and reduces stress on the affected area.
- Bone injury: In this procedure, healthy bone is transplanted from another part of the body to the affected area.
- Joint replacement: This surgery removes and substitutes an arthritic or injured joint with an artificial joint. This can be considered only after other treatments have failed to alleviate pain or disability.
Other treatments may comprise electrical inspiration and combination therapies to promote bone growth.
Complications of avascular necrosis
Untreated avascular necrosis worsens over time. Eventually, the bone can collapse. Avascular necrosis also causes the bone to lose its smooth shape, which could lead to severe arthritis.
Prevention of avascular necrosis
To reduce your risk of avascular necrosis and improve your overall health:
- Restrict alcohol consumption: Excessive alcohol consumption is one of the main risk factors for developing avascular necrosis.
- Keep cholesterol levels low: Small pieces of fat are the most common substance that blocks the blood supply to the bones.
- Monitor steroid use: Be sure to tell your doctor about your past or present use of high-dose steroids. Steroid-related bone damage seems to worsen with repeated cycles of high-dose steroids.
- Do not smoke: Smoking increases your risk.