Boneporosis

Osteonecrosis

Osteonecrosis means the death of bone tissue after reduced blood supply. When osteonecrosis attacks bone tissue near a joint, the joint surface may fail, leading to arthritis.

Osteonecrosis most commonly hits the hip, the humerus, knees, clavicle, scapula, and ankles, although any part of the skeleton can be affected. A particular form is osteonecrosis of the jaw, a which has different causes and requires different treatments from osteonecrosis.

Incidence

It is estimated that 10,000 to 20,000 patients are diagnosed with osteonecrosis each year in the United States alone.  Experts feel underdiagnosis is a problem.  It primarily afflicts people in their 20s, 30s, and 40s. Eight times as many men get it as women.

Causes

Osteonecrosis occurs when blood flow to a bone is interrupted or reduced. It can be caused by an injury (traumatic) or can occur spontaneously (non-traumatic).

Traumatic osteonecrosis is the most common. The blood flow to a part of bone can be affected if the bone is fractured or the joint becomes dislocated.

Non-traumatic osteonecrosis occurs even when the patient did not experience injury. The most common causes are long-term use of medications called corticosteroids and long-term alcoholism. Those account for over 95% of cases.  Less common causes are: blood disorders, liver disease, radiotherapy, chemotherapy, decompression sickness (which occurs in divers), dialysis, and organ transplants. Immunosuppressive regimens also lead to osteonecrosis.   HIV patients are estimated to have 100 times as high a risk of osteonecrosis as healthy people.

In about 20% of patients the cause remains unknown (idiopathic osteonecrosis).

Interestingly, nontraumatic osteonecrosis shows the tendency to symmetry in the human anatomy.  When is shows up in one part of the skeleton, it also ends up on the opposite side of the body about 60% of the time.

People who take bisphosphonates — a type of medicine used to treat osteoporosis — sometimes develop osteonecrosis of the jaw. The risk is higher for patients with multiple myeloma, breast, lung or other cancers and Paget’s disease of bone, and patients who have received high doses of bisphosphonates intravenously to counteract the damage caused by cancer in the bones.

Symptoms

At early stages osteonecrosis might cause no or mild pain in the affected joint. In later stages, the pain increases gradually, and is accompanied with stiffness and a limitation of motion of the involved joint.  Over time the bone is afflicted with an increasing accumulation of tiny fractures.  These tiny fractures build up fast in “load-bearing” bones.  The hips are particularly vulnerable

The bone can collapse after the blood supply is compromised. Standing or walking worsens the pain and a limp develops.  It is usually a few months to two years from the time of the first symptom to loss of joint function.

Osteonecrosis of the jaw is characterized by pain, soft-tissue swelling and infection, loosening of teeth, exposed bone, and feelings of numbness or heaviness in the jaw.

Diagnosis

One clue for doctors is when patients do not correctly heal after fractures.  That suggests osteonecrosis.  Unexplained pain in common osteonecrosis sites (e.g. hip, knee) can also suggest osteonecrosis if there are risk factors present.

Magnetic resonance imaging (MRI) is considered the best method for diagnosing osteonecrosis because it shows diseased areas that are not yet causing any symptoms.

Bone scans are nuclear imaging tests that involve injecting a contrast substance into a vein. This material travels to the parts of the bones that are injured or healing, and shows up as bright spots on the imaging plate.

X-rays scans look normal at early stages of the disease; only later in evolution do bone damage and osteoarthritis become evident on X-ray images. Computed tomography (CT) scans are more precise than traditional X-rays and bone scans, but less sensitive than MRI.

Biopsy of the bone is a conclusive tests, but rarely used as it requires surgery.

Treatment

The goal in treating osteonecrosis is to improve the patient’s use of the affected joint, stop further damage, and ensure bone and joint survival. Without treatment, patients generally experience severe pain and limitation in movement within two years.

Nonsurgical treatment

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, relieve pain and inflammation associated with osteonecrosis.  NSAIDs are available as over-the-counter products and as prescription medications.

Reducing weight bearing on the affected bones, by using canes, crutches or a walker, may slow the osteonecrosis-induced damage. They can help protect the joint until surgery.

Range-of-motion exercises (a staple of occupational health therapy) help keep the affected joints mobile and effective. Electrical stimulation can stimulate bone growth, either during surgery, applied directly to the damaged area, or through electrodes attached to the skin.  This is somewhat of an esoteric treatment, however, and most osteonecrosis patients will not have it.

For the osteonecrosis of the jaw, medical options include scraping away the damaged bone, taking antibiotics orally, using mouth rinses and avoiding invasive dental procedures.  Typical dental surgery can make osteonecrosis worse.

These nonsurgical treatments relieve pain, but usually are not permanent solutions.

 

Surgical treatment

Doctors usually recommend surgery for osteonecrosis.  The surgery can be put off for a while, but nonsurgical therapies are not effective enough. There are a number of surgical procedures that slow or stop progression of the disorder. Surgical procedures include:

 

Osteonecrosis means the death of a bone tissue caused by an impaired blood supply. When osteonecrosis attacks bone tissue near a joint, the joint surface may collapse, leading to arthritis. Osteonecrosis is also known as avascular necrosis, aseptic necrosis, or ischemic necrosis.

Although it can occur in any bone, osteonecrosis most commonly affects the hip, the upper arm bone, knees, shoulders, and ankles. A particular form is osteonecrosis of the jaw, a rare condition that has different causes and requires different treatments from osteonecrosis in other parts of the skeleton.

Incidence

It is estimated that 10,000 to 20,000 patients are diagnosed with osteonecrosis each year in the United States alone. It primarily afflicts people in their 20s, 30s, and 40s.

Causes

Osteonecrosis occurs when blood flow to a bone is interrupted or reduced. It can be caused by an injury (traumatic) or can occur spontaneously (non-traumatic).

Traumatic osteonecrosis is the most common. The blood flow to a part of bone can be affected if the bone is fractured or the joint becomes dislocated.

Non-traumatic osteonecrosis occurs without direct trauma or injury. The most common causes are high doses of corticosteroids, especially when given for long periods of time, and chronic alcohol use. More rarely, several conditions or procedures have been linked to osteonecrosis: certain blood disorders, liver disease, tumors, radiotherapy, chemotherapy, decompression sickness (in divers who surface too quickly), dialysis, and organ transplants. In about 20% of patients the cause remains unknown (idiopathic osteonecrosis).

Interestingly, if one bone has nontraumatic osteonecrosis, the same bone on the opposite side of the body also has it about 60% of the time, even if symptoms are absent.

People who take bisphosphonates — a type of medicine used to treat osteoporosis — sometimes develop osteonecrosis of the jaw. The risk is higher for patients with multiple myeloma, breast, lung or other cancers and Paget’s disease of bone, and patients who have received high doses of bisphosphonates intravenously to counteract the damage caused by cancer in the bones.

Symptoms

At early stages osteonecrosis might cause no or mild pain in the affected joint. As the disease progresses, the pain increases gradually, and is associated with stiffness and a limitation of motion of the involved joint.

More and more tiny fractures may occur, particularly in bones that support weight, such as the hip. Subsequently, the bone usually collapses after the blood supply is cut off. Standing or walking worsens the pain and a limp develops.

The period of time between the first symptoms and loss of joint function is different for each person; it typically ranges from several months to two years.

Osteonecrosis of the jaw is characterized by pain, soft-tissue swelling and infection, loosening of teeth, exposed bone, and feelings of numbness or heaviness in the jaw.

Diagnosis

Doctors often suspect osteonecrosis in people who do not corectly heal or improve satisfactorily after fractures or who develop unexplained pain in the hip, knee, or shoulder, particularly if there are risk factors present.

X-rays scans look normal at early stages of the disease; only later in evolution do bone damage and osteoarthritis become evident on X-ray images.

Magnetic resonance imaging (MRI) is the most sensitive method for diagnosing osteonecrosis because it shows diseased areas that are not yet causing any symptoms.

Bone scans are nuclear imaging tests that involve injecting a contrast substance into a vein. This material travels to the parts of the bones that are injured or healing, and shows up as bright spots on the imaging plate.

Computed tomography (CT) scans shows "slices" of the bone, making the picture much clearer than X-rays and bone scans, but less sensitive than MRI.

Biopsy and functional evaluation of the bone are very conclusive tests, but they are rarely used as they requires surgery.

Treatment

The goal in treating osteonecrosis is to improve the patient’s use of the affected joint, stop further damage, and ensure bone and joint survival. Without treatment, most patients experience severe pain and limitation in movement within two years.

Nonsurgical treatment

Nonsurgical treatment may relieve pain or help in the short term, for most people but it does not bring lasting improvement.

Nonsteroidal anti-inflammatory drugs, such as aspirin or ibuprofen, may help relieve pain and inflammation associated with osteonecrosis.

Reducing weight bearing on the affected bones, by using canes, crutches or a walker, may slow the damage caused by osteonecrosis and permit natural healing. They can help protect the joint until surgery.

Range-of-motion exercises may be useful to keep the affected joints mobile and increase their range of motion. Electrical stimulation can be used to induce bone growth, either during surgery, applied directly to the damaged area, or through electrodes attached to the skin.

For the osteonecrosis of the jaw, medical options include scraping away the damaged bone, taking antibiotics orally, using mouth rinses and avoiding invasive dental procedures, as dental surgery may exacerbate the condition.

Surgical treatment

Most people with osteonecrosis will eventually need surgery. There are a number of surgical procedures that slow or stop progression of the disorder. Surgical procedures include:

  • Core decompression (removal of the inner cylinder of bone, which reduces pressure within the bone, relieves pain, increases blood flow to the bone, and allows more blood vessels to form);
  • Bone grafting (transplanting bone from one site to another);
  • Osteotomy (reshaping the bone to reduce stress on the affected area);
  • Total joint replacement or arthroplasty (replacing the diseased joint with artificial parts). This is the only effective procedure to relieve pain and restore motion if osteonecrosis has caused significant joint collapse and osteoarthritis.
  • Surface replacement arthroplasty (placing a metal cap over the femoral head rather than replacing the entire joint as is done in a standard total hip replacement).



 

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Osteoporosis Facts

1) Weak bones and thin bones are more likely to break.

2) Your bones get weaker as you get older. You can fight back with exercise.

3) Bone density tests are fast and painless. Follow your doctor's recommendations.

4) Men and women can both get osteoporosis

5) It's a silent disease and you won't be aware your bones are weak until you get a bone scan or a break.

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Related Resources

NIH Questions and Answers about Avascular Necrosis

American College of Rheumatology on Osteonecrosis

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