What are the other Names for this Condition? (Also known as/Synonyms)

• Aseptic Necrosis
• Avascular Necrosis (AVN)
• Ischemic Bone Necrosis

What is Osteonecrosis? (Definition/Background Information)

• Osteonecrosis (or Avascular Necrosis) is a serious bone disorder characterized by the temporary or permanent disruption of blood supply to the bone, which causes cells and tissues within the affected bone to die
• It can result from a variety of factors such as sports injuries, alcoholism, use of certain medications, lupus, inflammatory bowel disease (such as Crohn’s disease), sickle cell anemia, and cancer
• Individuals, who develop Osteonecrosis, begin to experience pain within the affected bone/joint that usually progresses slowly. This may be accompanied by tenderness and swelling around the bone
• In many, Osteonecrosis involves the ends of the long bones in the body; frequently, the thigh bone and knee joint is affected. Normally, only one bone is involved; although, it is not uncommon for more than one bone to be affected
• Treatment associated with Osteonecrosis depends on the bone involved, but may include both nonsurgical and surgical methods. With early diagnosis and appropriate treatment, the prognosis is usually good

Who gets Osteonecrosis? (Age and Sex Distribution)

• Osteonecrosis may occur in individuals of all age, race, ethnic groups, and any gender
• A high percentage of individuals who develop the condition are young, middle-aged, or slightly older men in the age group 30-60 years

What are the Risk Factors for Osteonecrosis? (Predisposing Factors)

Common risk factors associated with Osteonecrosis include:

• Excessive consumption of alcohol is a major risk factor
• Individuals, who sustain a dislocation or fracture while participating in sports such as football or hockey
• Myeloproliferative disorder: A bone marrow disorder characterized by the abnormal increase of red blood cells
• Systemic lupus erythematosus: Autoimmune systemic inflammatory conditions that occur when an individual’s immune system create antibodies, which accidentally attack one’s healthy tissues and organs within the body
• Decompression sickness: A disorder characterized by abnormal formation of nitrogen bubbles within the blood and tissues, usually seen in divers, when they move up from the water (high-pressure medium) to the surface (low-pressure medium) too soon
• Sickle cell anemia: An inherited condition characterized by crescent-shaped red blood cells in the body, obstructing blood flow and causing reduced amounts of oxygen transportation
• Gaucher’s disease: A rare inherited disorder caused by excessive accumulation of fatty substances (lipid) in the cells and certain organs. This excess build-up of fatty substances can prevent the liver, spleen, lungs, bone marrow, and in rare cases the brain, from functioning properly
• Crohn’s disease: A disease causing inflammation of the digestive tract lining
• Arterial embolism: Blood flow obstruction to an organ or body part, caused due to an embolus (a blood clot or fat particle) within the artery
• Thrombosis: Blood clot that occurs within blood vessels
• Vasculitis: A condition that causes inflammation of blood vessels
• Prolonged consumption of a steroidal medication, such as prednisone

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Osteonecrosis? (Etiology)

The causative factors associated with Osteonecrosis may include the following conditions:

• Injuries during sports participation or vehicular accidents
• Excessive alcohol consumption
• Individuals with HIV infection or AIDS
• Perthes disease: Children who develop a rare childhood hip disorder caused by the temporary loss of blood flow to the ball portion of the hip joint
• Peripheral vascular disease: The contraction and hardening of blood vessels within the legs and feet
• Slipped capital femoral epiphysis: Adolescents develop this unusual condition, due to a weakness of the growth plate, causing the femur/thighbone head to slip backwards
• Sickle cell anemia: A genetic condition caused by odd-shaped red blood cells that tend to obstruct the flow of blood to different body parts
• Systemic lupus erythematosus (or lupus): An auto-immune systemic inflammatory condition that occurs when an individual’s immune system create antibodies that accidentally attack healthy tissues and organs within the body
• Decompression sickness: A disorder characterized by abnormal formation of nitrogen bubbles within the blood and tissues, usually seen in divers when they move up from the water to the surface too soon
• Radiation therapy, which uses high-energy beams to shrink tumors and destroy cancer cells
• Use of certain medications, such as during chemotherapy, steroids (usually high-dose), or immunosuppressive medications for organ transplant

In Osteonecrosis, there is a loss of blood supply to the bone leading to its destruction and necrosis (tissue death). This blood supply loss may occur from a variety of factors (traumatic or atraumatic) mentioned above. In some cases, the exact cause of Osteonecrosis may remain unidentified (idiopathic).

What are the Signs and Symptoms of Osteonecrosis?

The signs and symptoms of Osteonecrosis may be mild or severe and can vary from one individual to another. It also depends on the specific bone to which the blood supply is cut-off. In some cases, there may be the involvement of more than one bone. Also, initially, there may not be any noticeable symptoms.

The signs and symptoms may of Osteonecrosis include:

• Noticeable pain and tenderness in the affected bone; the pain increases when pressure is applied to the bone
• Swelling of tissue around the affected bone or joint
• Decreased range of motion of the affected joint/bone
• Commonly involved bones include those of the thigh, knee, ankles, upper arm, and shoulders
• One or more bones may be affected; this may happen concurrently or during different time periods
• Osteonecrosis of the knee may result in difficulty bending the knee and in walking
• Osteonecrosis of the hip may increase one’s difficulty to walk or sit

Additionally, the signs and symptoms of the associated/underlying condition (if any present) may be noted.

How is Osteonecrosis Diagnosed?

Diagnostic methods that a physician may use to help diagnose Osteonecrosis include:

• Physical examination and evaluation of medical history
• Assessment of the signs and symptoms
• Functional evaluation of the affected bone
• Tests and procedures to diagnose any underlying condition, if any
• X-ray of the affected region: X-rays can help the physician rule-out other possible causes of knee discomfort. During the early stages of Osteonecrosis, it is difficult to locate the appearance of any abnormal bone changes. However, X-rays can usually identify the presence of Osteonecrosis during the later stages
• Magnetic resonance imaging (MRI): An MRI is an imaging technique that creates images of soft tissues and bones, which helps detect any bone abnormalities during the early stages of Osteonecrosis
• Bone scan: A bone scan is a diagnostic method used to identify any bone abnormalities by injecting tiny amounts of radioactive material into the bloodstream
• Computerized tomography (CT): A CT scan takes a series of X-ray images from several different angles, which are then merged to create cross-sectional images of bones and soft tissues of the body. This allows a physician to examine the bone or joint and its surrounding structures

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Osteonecrosis?

The complications associated with Osteonecrosis are based on the specific bone that is involved. Some of the complications may include:

• Further deterioration of the involved bone
• If left untreated, the bone may collapse
• Increased risk for fractures
• Immobility of the affected part/bone
• Chronic disability
• Complications that arise from the underlying condition, if any present

How is Osteonecrosis Treated?

The treatment of Osteonecrosis includes non-surgical and surgical methods. A healthcare provider may start with non-surgical treatment methods before adopting surgical procedures and techniques. These include:

• Applying ice to the region can help with pain and reduce swelling
• Avoiding further stress/weight on the involved bone, such as by using a pair of crutches; preventing further bone damage
• Non-steroidal anti-inflammatory oral medications, such as Ibuprofen and naproxen, may be used to help decrease pain and swelling
• Medications for Osteonecrosis may decrease the progression of this condition
• Corticosteroid injections help provide temporary relief of symptoms and in improving the range of motion. It is important to note that corticosteroid injections may only give temporary relief. Prolonged episodes of such injections can injure the joints in the long-run
• Electrical stimulation therapy to aid in the growth of the affected bone
• After the symptoms has decreased, it is important to begin some light motion exercises.  Physical therapy may help restore strength, as well as provide flexibility to the muscles

Surgical treatment measures include:

• Osteotomy: The affected bone is surgically removed/cut and reshaped or realigned
• Core decompression: Core decompression is used to treat early-stage Osteonecrosis. In this surgical procedure, the pressure within the bone is decreased by removing a part of the bone causing the abnormal pressure
• Partial or total replacement of the involved joint: The involved joint is replaced through a surgical procedure using a prosthetic implant. A physician will recommend this surgical procedure, if the condition is limited to a certain portion of the joint
• Total arthroplasty: In total arthroplasty, the involved joint cartilage is completely removed. It is then replaced by a metal and plastic prosthetic implant. This surgical procedure is recommended, if the entire joint is acutely affected
• Cartilage grafting: Cartilage grafting is a surgical procedure to replace the damaged cartilage, which may be damaged due to Osteonecrosis or any traumatic injury
• Bone grafting: It is a technique that involves removing a healthy bone from within the body and replacing the affected bone

Additionally, suitable treatment of any underlying condition/disorder should be undertaken.

How can Osteonecrosis be Prevented?

A few recommendations to help prevent Osteonecrosis include:

• Avoid excessive intake of alcoholic beverages
• Individuals, who participate in any high-risk sports, such as football or hockey, should wear appropriate safety equipment to help prevent a serious injury
• Undertaking adequate treatment for health conditions such as lupus
• Wear proper equipment while scuba-diving to avoid decompression sickness
• Monitor consumption of steroidal medications
• Maintain a low cholesterol diet
• Avail proper treatment that can help control or minimize blood vessel damage associated with vasculitis
• Proper treatment of Crohn’s disease will help prevent the development of Osteonecrosis
• Undertake proper treatment of myeloproliferative disorder
• If required, undertake treatments that improve the blood flow to organs or any body part
• Consider proper treatments of blood clots that occur within blood vessels

What is the Prognosis of Osteonecrosis? (Outcomes/Resolutions)

• If treated early, a high percentage of individuals who develop Osteonecrosis may show an improvement and experience favorable outcomes; the bone may rebuild itself
• In general, the amount of bone damaged by this condition significantly affects its prognosis. A delay in treatment or an absence of treatment can severely affect the prognosis and cause functional loss of the involved bone within 1-2 years

Additional and Relevant Useful Information for Osteonecrosis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/health-topics/orthopedc-disorders/