What Is Avascular Necrosis?
Article Sources
- 1. Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
- 2. Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis
- 3. Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases--conditions/osteonecrosis-of-the-hip
Avascular necrosis is known by several different names, including osteonecrosis1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859 and aseptic necrosis.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip Necrosis means “tissue death,” and AVN occurs when something cuts off the supply of blood to bone tissue, which often occurs at a joint. Without the oxygen from the blood, the tissue begins to die off, which can cause the bone to collapse.2Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis
Avascular necrosis most often occurs at the hip.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip However, any bone can be affected if something occurs to disrupt its blood supply. Though asymptomatic at first, AVN can cause significant pain and complications as the collapse of the bone progresses. While there is no way to reverse the damage from osteonecrosis, it may be possible to relieve the pain and prevent further bone loss.
1. Who Is Likely To Have Avascular Necrosis?
Every year, approximately 20,000 people in the United States have to go to the hospital for treatment of avascular necrosis. For reasons that are not entirely clear, men are more likely to develop AVN than women.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip
Compared to degenerative osteoarthritis, which tends to affect the elderly, osteonecrosis often develops in relatively young adults. Most people with AVN are between the ages of 30 and 50 when the condition is diagnosed.
2. What Causes Avascular Necrosis?
Avascular necrosis occurs when something disrupts the flow of blood to a bone. It is not always possible to determine the cause of the disrupted blood flow. Idiopathic AVN, or necrosis that occurs without a known cause, occurs in approximately 25% of cases.1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
Sometimes the diminished blood supply is the result of an underlying medical condition, such as Gaucher’s disease or sickle-cell anemia. Another common cause of AVN is damage to the blood vessels from traumatic injury to the bone.2Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis The buildup of fatty deposits in the cardiovascular system can cut off blood supply to the bone by blocking small blood vessels.
3. What Are the Symptoms of AVN?
Avascular necrosis can cause pain ranging from mild to severe. It typically develops in stages over several months to a year.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip During the early stages, there may be minimal to no pain. As the damage progresses, pain may become more pronounced with weight-bearing activity.1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
Eventually, the pain may be present even when not putting weight on the affected bone or joint. The pain of osteonecrosis can also reduce the affected joint’s range of motion.2Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis In the latter stages of hip AVN, the pain and reduced range of motion can make weight-bearing activities much more difficult.
4. What Are the Risk Factors for Avascular Necrosis?
Avascular necrosis is associated with medical conditions affecting the immune system, such as systemic lupus erythematosus and HIV/AIDS. Diabetes and pancreatitis can also contribute to AVN. Osteonecrosis may be a side effect of organ transplantation and radiation therapy for cancer.1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
Because fat deposits in blood vessels can contribute to avascular necrosis, it is more common in people with hyperlipidemia, i.e., high cholesterol.2Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis Excess alcohol consumption and high-dose corticosteroids can also increase lipid levels and cause the formation of fatty deposits in the blood vessels.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip
5. What Are the Possible Complications of AVN?
Avascular necrosis can cause severe arthritis if left untreated. The damage to the bone also causes the cartilage covering the bone at the joint articulation to collapse. This prevents the bones of the joint from gliding easily against one another, and irritation and inflammation of the joint are more likely to occur.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip
AVN also causes arthritis by changing the shape of the bone itself, causing the surface to become less smooth. The longer osteonecrosis goes untreated, the more likely collapse of the bone itself becomes.1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
6. How Is Avascular Necrosis Diagnosed?
As with other bone conditions, imaging studies may be useful for identifying avascular necrosis. Diagnosis may require more advanced imaging studies.2Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis However, AVN may show up on plain film X-rays, where it is often observed as a wedge-shaped area with a crescent sign, which is a distinctive area of radiolucency.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip
A doctor also often performs a physical exam to diagnose osteonecrosis. This involves evaluating the range of motion of the affected joint and checking for tenderness by gently palpating the area, i.e., feeling it with his or her hands.1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
7. What Are the Treatment Options for Avascular Necrosis?
A doctor may recommend medications to lower cholesterol, prevent blood clots, and relieve pain. The doctor may also prescribe physical therapy to improve range of motion or an assistive device to take pressure off the affected area while performing weight-bearing activities. Electrical stimulation may stimulate new bone formation.1Avascular necrosis. (2020, April 22). Retrieved from https://www.mayoclinic.org/diseases-conditions/avascular-necrosis/symptoms-causes/syc-20369859
Surgery is often the most effective treatment for avascular necrosis, especially in the early stages.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip Common surgical procedures to treat AVN include an osteotomy, which involves removing a segment of bone to relieve the pressure, and core decompression, which promotes the development of healthy bone tissue by removing an inner layer.2Avascular Necrosis. (n.d.). Retrieved October 21, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/avascular-necrosis Arthroplasty, or replacement of the joint with an artificial prosthesis, may be necessary for advanced cases of osteonecrosis involving bone collapse.
8. What Happens During Recovery From Surgery To Treat Avascular Necrosis?
The exact course of recovery depends partly on the type of surgical procedure performed. However, recovery from any surgery typically involves rest and avoiding putting pressure on the surgical site until it has had sufficient time to heal. Once the patient is allowed to resume weight-bearing activity, he or she may have to use an assistive device.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip
Rest and inactivity due to surgery can cause muscles to atrophy. Physical therapy may be necessary to restore strength to the muscles in anticipation of returning to full weight-bearing activities.
9. Is It Possible To Prevent Avascular Necrosis?
Preventing avascular necrosis involves reducing the risk factors that can disrupt the flow of blood to the bone. For example, smoking increases the risk of AVN because it can reduce circulation, so patients are advised to avoid tobacco use and undergo a smoking cessation program if currently using tobacco.
Deposits of lipids in the blood vessels are the most common cause of AVN, so patients can reduce the risk by maintaining low cholesterol levels. Patients should also limit alcohol consumption and monitor steroid use with the help of a doctor.
10. What Is the Prognosis for AVN?
Damage to the bone due to avascular necrosis is irreversible. However, many patients have good results with treatments meant to stimulate the development of new bone, such as core decompression and electrical stimulation. Treatments such as these are more likely to succeed if AVN is caught early, before bone collapse takes place.
Recovery from core decompression or joint arthroplasty procedures takes approximately three months. Many patients report complete resolution of pain following procedures such as these and eventually return to walking unaided.3Osteonecrosis of the Hip - OrthoInfo - AAOS. (n.d.). Retrieved October 21, 2020, from https://orthoinfo.aaos.org/en/diseases–conditions/osteonecrosis-of-the-hip
