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

• Avascular Bone Necrosis of Knee
• Avascular Necrosis of the Knee
• Ischemic Bone Necrosis of the Knee

What is Osteonecrosis of the Knee? (Definition/Background Information)

• Osteonecrosis is a serious disorder characterized by the temporary or permanent disruption of blood supply to the bone, which causes cells within the affected bone to die
• Osteonecrosis of the Knee is a gradually developing disorder that does not cause any significant signs and symptoms in the early stages. Over time, there may be painful episodes in the affected region of the knee joint
• Excessive consumption of alcohol may lead to the development of the condition. Middle-aged men are known to have the highest rate of incidence of Osteonecrosis of the Knee
• The cause of Osteonecrosis of the Knee includes a variety of conditions and disorders, such as peripheral vascular disease, slipped capital femoral epiphysis, sickle cell anemia, decompression sickness, and any therapy that tends to damage the healthy bone cells in the body, such as radiation therapy
• The treatment of Osteonecrosis of the Knee primarily focuses on addressing the underlying causative condition and includes both nonsurgical and surgical methods. With early treatment, the prognosis is usually good; however, this also depends on the cause of Osteonecrosis of the Knee and severity of damage to the bone

Who gets Osteonecrosis of the Knee? (Age and Sex Distribution)

• Osteonecrosis of the Knee is more common in females compared to males
• The condition usually affects individuals between 30-50 years old
• There is no known ethnic or racial preference for Osteonecrosis of the Knee
• it is seen all over the world; there is no particular geographical restriction

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

The common risk factors associated with Osteonecrosis of the Knee include:

• Excessive consumption of alcohol may lead to its development
• Individuals, who sustain a dislocated/fractured knee, while participating in sports such as football
• Myeloproliferative disorder: A bone marrow disorder characterized by the abnormal increase of red blood cells
• Systemic lupus erythematosus (SLE): Autoimmune systemic inflammatory conditions that occur when an individual’s immune system create antibodies, which accidentally attack healthy tissues and organs within the body
• Acute human immunodeficiency virus (HIV) infection: A viral infection that slowly attacks the immune system
• 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
• 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 a fat particle) within the artery
• Thrombosis: Blood clot that occurs within the blood vessels
• Pancreatitis: A disease resulting in inflamed pancreas
• Vasculitis: A condition that causes inflammation of the blood vessels
• Hyperlipidemia: A hereditary disorder characterized by high amounts of lipids (fat) in the body and blood
• Organ transplantation
• 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 of the Knee? (Etiology)

Causes associated with Osteonecrosis of the Knee may include:

• Individuals, who fracture or dislocate their bones, while participating in sports
• Long-term cortical steroid therapies
• Peripheral vascular disease: The contraction and hardening of blood vessels in the legs and feet
• Venous hypertension
• 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
• Systemic lupus erythematosus (or lupus): An autoimmune systemic inflammatory condition that occurs when an individual’s immune system create antibodies that accidentally attack healthy tissues and organs within the body
• Radiation therapy using high-energy beams to shrink tumors and destroy cancer cells
• Chemotherapy: A therapeutic approach involving a combination of drugs to kill cancerous cells
• Conditions resulting in increased thrombosis, such as:
  • 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
  • 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
  • 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
  • Excessive alcohol consumption

Osteonecrosis of the Knee may also occur in many individuals without any identifiable causes.

What are the Signs and Symptoms of Osteonecrosis of the Knee?

Osteonecrosis of the Knee usually does not cause significant signs and symptoms during the early phases. However, as the condition progresses, there is increased bone pain or joint pain. The following signs and symptoms may be observed:

• Noticeable pain and tenderness in the knee
• Swelling of tissue around the affected bone or joint
• Reduced ability to walk
• Decreased range of motion of the affected joint/bone
• Large areas of bone become necrotic, especially near a joint, resulting in joint collapse
• If this condition is not treated early, it can result in severe osteoarthritis of the affected joint

How is Osteonecrosis of the Knee Diagnosed?

Osteonecrosis of the Knee may be diagnosed by the following observations and tests:

• Physical examination and evaluation of medical history
• X-ray of the knee joint: X-rays are utilized to visualize images of the knee. It can also 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 of the Knee, during the later stages
• Magnetic resonance imaging (MRI) scan of the knee joint: 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 of the affected region: 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) of the affected region: 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 knee joint and its surrounding structures
• Ultrasound studies of the knee joint: The use of high-frequency sound waves to generate a thorough image of the knee
• Occasionally, a biopsy may be required to confirm the diagnosis

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 of the Knee?

The complications of Osteonecrosis of the Knee may include:

• Long-term osteoarthritis of the knee joint
• If left untreated, collapse of the bone causing severe joint dysfunction
• Chronic disability

How is Osteonecrosis of the Knee Treated?

The treatment of Osteonecrosis in the Knee may include both nonsurgical and surgical methods. A healthcare provider may start with non-surgical treatment methods before adopting more invasive procedures and techniques. These include:

• Rest: Any activity that aggravates the knee condition should be avoided. The physician usually advises individuals to refrain from activities, until the symptoms improve
• Applying ice to the knee can help with pain and reduce swelling
• Non-steroidal anti-inflammatory oral medications, such as Ibuprofen and naproxen, may be used to help decrease knee pain and swelling
• Medications for osteonecrosis may decrease the progression of this condition
• Stretching exercises
• Corticosteroid injections help provide temporary relief of symptoms, and in improving the range of motion. It is important to note that corticosteroid injections only give temporary relief. Prolonged episodes of such injections, may injure the joints in the long-run
• 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:

• Partial knee replacement: Partial knee replacement is a surgical procedure that involves the removal of one part of the knee joint. A physician will recommend this surgical procedure if this disorder is limited to a certain area of the knee. Part of the knee is then removed and replaced by a prosthetic implant
• Total knee arthroplasty: In total knee arthroplasty, the knee joint cartilage is completely removed. It is then replaced by a metal and plastic prosthetic implant. This surgical procedure is recommended, if the entire knee joint is acutely affected
• Cartilage grafting: Cartilage grafting is a surgical procedure to replace the damaged knee cartilage, which may be damaged due to osteonecrosis, or any traumatic injury
• Core decompression: Core decompression is used to treat early stage osteonecrosis. In this surgical procedure the pressure in the bone is decreased by removing a part of the bone causing the abnormal pressure

How can Osteonecrosis of the Knee be Prevented?

In some cases, prevention of Osteonecrosis of the Knee may be possible by considering the following measures:

• Avoid excessive intake of alcoholic beverages
• Individuals, who participate in any high-risk sports, such as football, should wear appropriate safety equipment to help prevent a serious injury
• Undertake a proper treatment of lupus
• Consider appropriate treatment of sickle cell disease, if present
• Judicious use of long-term steroid therapy; monitor consumption of steroidal medications
• Careful decompression during deep sea diving will decrease the chances of nitrogen bubbles being formed in the blood vessels
• 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 can help prevent the development of Osteonecrosis of the Knee
• Undertake proper treatment of any myeloproliferative disorders
• Avail treatments that improve the blood flow to organs or any body part
• Proper treatment of blood clots that occur in the blood vessels

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

The prognosis of Osteonecrosis of the Knee depends on this severity of signs and symptoms, the area of bone necrosis, and certain underlying risk factors.

• The prognosis also depends upon the location of the affected bone and the amount of bone necrosis
• In some cases, the condition gets better without any medical intervention, especially when only a small area of the bone is involved
• Individuals who respond to treatment measures have better prognosis than those who do not respond to them
• The amount of bone damaged by this disorder significantly affects its prognosis

Additional and Relevant Useful Information for Osteonecrosis of the Knee:

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

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