Osteonecrosis
Publication Date: January 2001
Revised March 2006
Questions and Answers about Osteonecrosis (Avascular Necrosis)
What Is Osteonecrosis?
Osteonecrosis is a disease resulting from the temporary or permanent loss
of blood supply to the bones. Without blood, the bone tissue dies, and ultimately
the bone may collapse. If the process involves the bones near a joint, it often
leads to collapse of the joint surface. Osteonecrosis is also known as avascular
necrosis, aseptic necrosis, and ischemic necrosis.
Although it can happen in any bone, osteonecrosis most commonly affects the
ends (epiphysis) of the femur, the bone extending from the knee joint to the
hip joint. Other common sites include the upper arm bone, knees, shoulders, and
ankles. The disease may affect just one bone, more than one bone at the same
time, or more than one bone at different times. According to the American Academy
of Orthopaedic Surgeons, 10,000 to 20,000 people develop osteonecrosis each year,
and most of them are between 20 and 50 years of age. Osteonecrosis is the underlying
diagnosis in approximately 10 percent of hip replacements. Orthopaedists - doctors
who specialize in the diagnosis and treatment of injuries and diseases of the
musculoskeletal system - most often diagnose this disease.
The amount of disability that results from osteonecrosis depends on what part
of the bone is affected, how large an area is involved, and how effectively the
bone rebuilds itself. Normally, bone continuously breaks down and rebuilds -
old bone is replaced with new bone. This process - which takes place after an
injury as well as during normal growth - keeps the skeleton strong and helps
it to maintain a balance of minerals. In the course of osteonecrosis, however,
the healing process is usually ineffective and the bone tissues break down faster
than the body can repair them. If left untreated, the disease progresses, the
bone collapses, and the joint surface breaks down, leading to pain and arthritis.
* What Causes Osteonecrosis?
* Who Is Likely to Develop Osteonecrosis?
* What Are the Symptoms?
* How Is Osteonecrosis Diagnosed?
* What Treatments Are Available?
* What Research Is Being Done to Help People With Osteonecrosis?
* Where Can People Find More Information About Osteonecrosis?
* Key Words
What Causes Osteonecrosis?
Osteonecrosis is caused by impaired blood supply to the bone, but it is not
always clear what causes that impairment. Osteonecrosis often occurs in people
with certain risk factors (such as high-dose corticosteroid use and excessive
alcohol intake) and medical conditions. However, it also affects people with
no health problems and for no known reason. Following are some potential causes
of osteonecrosis and other health conditions associated with its development.
Steroid Medications
Aside from injury, one of the most common causes of osteonecrosis is the use
of corticosteroid medications such as prednisone. Corticosteroids are commonly
used to treat inflammatory diseases such as systemic lupus erythematosus, rheumatoid
arthritis, inflammatory bowl disease, severe asthma, and vasculitis. Studies
suggest that long-term use of oral or intravenous (IV) corticosteroids is associated
with nontraumatic osteonecrosis. Patients should discuss concerns about steroid
use with their doctor.
Doctors are not sure exactly why the use of corticosteroids sometimes leads
to osteonecrosis. They speculate that the drugs may interfere with the body's
ability to break down fatty substances called lipids. These substances then build
up in and clog the blood vessels, causing them to narrow and to reduce the amount
of blood that gets to the bone. Some studies suggest that corticosteroid-related
osteonecrosis is more severe and more likely to affect both hips (when occurring
in the hip) than osteonecrosis resulting from other causes.
Alcohol Use
Excessive alcohol use is another common cause of osteonecrosis. People who
drink alcohol in excess can develop fatty substances that may block blood vessels,
causing a decreased blood supply to the bones.
Injury
When a fracture, a dislocation, or some other joint injury occurs, the blood
vessels may be damaged. This can interfere with the blood circulation to the
bone and lead to trauma-related osteonecrosis. In fact, studies suggest that
hip dislocation and hip fractures are major risk factors for osteonecrosis.
Increased pressure within the bone may be another cause of osteonecrosis.
When there is too much pressure within the bone, the blood vessels narrow, making
it hard for them to deliver enough blood to the bone cells. The cause of increased
pressure is not fully understood.
Other Risk Factors
Other risk factors for osteonecrosis include radiation therapy, chemotherapy,
and organ transplantation (particularly kidney transplantation). Osteonecrosis
is also associated with a number of medical conditions, including cancer, lupus,
blood disorders such as sickle cell disease, HIV infection, Gaucher's disease,
Caisson disease, gout, vasculitis, osteoarthritis, and osteoporosis.
Who Is Likely to Develop Osteonecrosis?
Osteonecrosis affects both men and women. It can occur in people of any age,
from children to the elderly. However, it is most common in people in their thirties,
forties, and fifties.
What Are the Symptoms?
In the early stages of osteonecrosis, people may not have any symptoms. As
the disease progresses, however, most experience joint pain. At first, the pain
occurs only when putting weight on the affected joint. Later, it occurs even
when resting. Pain usually develops gradually, and may be mild or severe. If
osteonecrosis progresses and the bone and surrounding joint surface collapse,
pain may develop or increase dramatically. Pain may be severe enough to limit
range of motion in the affected joint. In some cases, particularly those involving
the hip, disabling osteoarthritis may develop. The period of time between the
first symptoms and loss of joint function is different for each person, but it
typically ranges from several months to more than a year.
How Is Osteonecrosis Diagnosed?
After performing a complete physical examination and asking about the patient's
medical history, the doctor may use one or more bone imaging techniques to diagnose
osteonecrosis. As with many other diseases, early diagnosis increases the chances
of treatment success. The tests described below may be used to determine the
amount of bone affected and how far the disease has progressed.
X Ray
A radiograph, or x ray, is probably the first test the doctor will recommend.
A simple way to produce pictures of bones, an x ray is often useful in diagnosing
the cause of joint pain. For osteonecrosis, however, x rays are not sensitive
enough to detect bone changes in the early stages of the disease. So if the x
ray is normal, the doctor may order more tests. In later stages of osteonecrosis,
x rays may show bone damage, and once the diagnosis is made, they are often used
to monitor disease progression.
Magnetic Resonance Imaging (MRI)
Research studies have shown that magnetic resonance imaging, or MRI, is the
most sensitive method for diagnosing osteonecrosis in the early stages. Unlike
x rays, bone scans, and CT (computed/computerized tomography) scans (see below),
MRI detects chemical changes in the bone marrow. MRI provides the doctor with
a picture of the affected area and the bone-rebuilding process. In addition,
MRI may show diseased areas that are not yet causing any symptoms. Some doctors
caution against aggressive treatment of osteonecrosis that has been detected
by MRI but is not causing symptoms. One study has shown evidence that for a select
group of patients in the early stages of osteonecrosis, the disease may improve
spontaneously.
Computed/Computerized Tomography (CT scan)
A CT scan is an imaging technique that provides the doctor with a three-dimensional
picture of the bone. It also shows "slices" of the bone, making the
picture much clearer than x rays and bone scans. Some doctors disagree about
the usefulness of this test to diagnose osteonecrosis. Although a diagnosis usually
can be made without a CT scan, the technique may be useful in determining the
extent of bone damage. CT scans are less sensitive than MRIs.
Bone Scan
A type of test called technetium-99m bone scanning is used most commonly in
patients who have normal x rays and no risk factors for osteonecrosis. In this
test, a harmless radioactive material is injected through an intravenous line,
and a picture of the bone is taken with a special camera. The picture shows how
the injected material travels through blood vessels in bone. A single bone scan
finds all areas in the body that are affected, thus reducing the need to expose
the patient to more radiation.
Biopsy
A biopsy is a surgical procedure in which a tissue sample from the affected
bone is removed and studied. Although a biopsy is a conclusive way to diagnose
osteonecrosis, it is rarely used because it requires surgery.
Functional Evaluation of Bone
Tests to measure the pressure inside a bone may be used when the doctor strongly
suspects that a patient has osteonecrosis, despite normal results of x rays,
bone scans, and MRIs. These tests are very sensitive for detecting increased
pressure within the bone, but they require surgery.
What Treatments Are Available?
Appropriate treatment for osteonecrosis is necessary to keep joints from breaking
down. Without treatment, most people with the disease will experience severe
pain and limitation in movement within 2 years. To determine the most appropriate
treatment, the doctor considers the following:
* the age of the patient
* the stage of the disease (early or late)
* the location and whether bone is affected over a small or large area
* the underlying cause of osteonecrosis. With an ongoing cause such as corticosteroid
or alcohol use, treatment may not work unless use of the substance is stopped.
The goal in treating osteonecrosis is to improve the patient's use of the
affected joint, stop further damage to the bone, and ensure bone and joint survival.
To reach these goals, the doctor may use one or more of the following surgical
or nonsurgical treatments.
Nonsurgical Treatments
Usually, doctors will begin with nonsurgical treatments, alone or in combination.
Unfortunately, although these treatments may relieve pain or help in the short
term, for most people they don't bring lasting improvement.
* Medications - Nonsteroidal anti-inflammatory drugs (NSAIDs) are often prescribed
to reduce pain. People with clotting disorders may be given blood thinners to
reduce clots that block the blood supply to the bone. Cholesterol-lowering medications
may be used to reduce fatty substances (lipids) that increase with corticosteroid
treatment (a major risk factor for osteonecrosis). In one study, people who took
cholesterol-lowering medications called statins along with corticosteroids significantly
reduced the risk of developing osteonecrosis in the first place.
* Reduced weightbearing - If osteonecrosis is diagnosed early, the doctor may
begin treatment by having the patient remove weight from the affected joint.
The doctor may recommend limiting activities or using crutches. In some cases,
reduced weightbearing can slow the damage caused by osteonecrosis and permit
natural healing. When combined with pain medication, reduced weightbearing can
be an effective way to avoid or delay surgery for some patients.
* Range-of-motion exercises - An exercise program involving the affected joints
may help keep them mobile and increase their range of motion.
* Electrical stimulation - This treatment has been used in several centers to
induce bone growth, and in some studies has been helpful when used prior to femoral
head collapse.
Surgical Treatment
A number of different surgical procedures are used to treat osteonecrosis.
Most people with osteonecrosis will eventually need surgery.
* Core decompression - This surgical procedure removes the inner cylinder
of bone, which reduces pressure within the bone, increases blood flow to the
bone, and allows more blood vessels to form. Core decompression works best in
people who are in the earliest stages of osteonecrosis, often before the collapse
of the joint. This procedure sometimes reduces pain and slows the progression
of bone and joint destruction.
* Osteotomy - This treatment involves reshaping the bone to reduce stress on
the affected area. Recovery can be a lengthy process, requiring 3 to 12 months
of very limited activities. This procedure is most effective for patients with
early-stage osteonecrosis and those with a small area of affected bone.
* Bone graft - This is the transplantation of healthy bone from another part
of the body. It is often used to support a joint after core decompression. In
many cases, the surgeon will use what is called a vascular graft - which includes
an artery and vein - to increase the blood supply to the affected area. Recovery
from a bone graft can take from 6 to 12 months. The procedure is complex and
its effectiveness is unproven. Clinical studies are underway to determine its
effectiveness.
* Arthroplasty/total joint replacement - Total joint replacement is the treatment
of choice in late-stage osteonecrosis and when the joint is destroyed. In this
surgery, the diseased joint is replaced with artificial parts. Total joint replacement,
or sometimes femoral head resurfacing, is often recommended for people for whom
other efforts to preserve the joint have failed. Various types of replacements
are available, and people should discuss specific needs with their doctor.
For most people with osteonecrosis, treatment is an ongoing process. Depending
upon the stage of the disease, doctors may first recommend the least complex
or nonoperative treatment plans, such as medication or reduced weightbearing.
If these modalities are unsuccessful, surgical treatments may be needed. It is
important that patients carefully follow instructions about activity limitations
and work closely with their doctors to ensure that appropriate treatments are
used.
What Research Is Being Done to Help People With Osteonecrosis?
With proper treatment, most people with osteonecrosis can lead productive
lives. But there is still a lot to learn about prevention, diagnosis, and treatment.
Some goals of current research are to:
* better understand how many people are affected by osteonecrosis by screening
at-risk populations with MRI (magnetic resonance imaging)
* identify risk factors
* determine if genetic clotting disorders are risk factors for developing osteonecrosis
in at-risk populations
* identify and/or develop new ways to diagnose osteonecrosis in its earliest
stages, when nonsurgical treatment is most likely to help
* determine whether biological therapies, such as recombinant human bone morphogenic
protein, are effective treatments for osteonecrosis
* develop new treatments and improve available treatments for osteonecrosis
* study key mechanical factors - such as the alignment of the hips, knees, and
ankles - that influence treatment outcomes
* develop an animal model of osteonecrosis to study the disease
* improve hip replacement techniques and materials so that younger patients will
not need more than one hip replacement in their lifetime
* better understand the body's reaction to steroids and why taking steroids increases
a person's risk of developing osteonecrosis.
Where Can People Find More Information About Osteonecrosis?
*
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301-495-4484
Toll Free: 877-22-NIAMS (226-4267)
TTY: 301–565–2966
Fax: 301-718-6366
Email: NIAMSinfo@mail.nih.gov
Website: http://www.niams.nih.gov
NIAMS provides information about various forms of arthritis and rheumatic
disease and bone, muscle, joint, and skin diseases. It distributes patient and
professional education materials and refers people to other sources of information.
Additional information and updates can also be found on the NIAMS Web site.
*
American Academy of Orthopaedic Surgeons (AAOS)
P.O. Box 2058
Des Plaines, IL 60017
Toll Free: 800-824-BONE (2663)
Email: pemr@aaos.org
Website: http://www.aaos.org
The academy is the professional society of bone and joint surgeons. It seeks
to further knowledge in the diagnosis and treatment of bone-related diseases.
The academy publishes brochures on total joint replacement, arthritis, arthroscopy,
and other subjects. Single copies of a brochure are available free of charge
by sending a self-addressed, stamped (business-size) envelope to (name of brochure)
at the address above.
*
National Osteonecrosis Foundation
5601 Loch Raven Blvd. Suite 201
Baltimore, MD 21239
Phone: 410–532–5985
Fax: 410–532–5908
Website: http://www.nonf.org
The foundation offers brochures, information on the disease, and a physician-finding
tool on its Web site.
Arthritis Foundation
P.O. Box 7669
Atlanta, GA 30357-0669
Phone: 404-872-7100
Toll Free: 800-283-7800
Website: http://www.arthritis.org
The Arthritis Foundation is the major voluntary organization devoted to supporting
arthritis research and providing educational and other services to individuals
with arthritis. It publishes free pamphlets and a magazine for members on all
types of arthritis. It also provides up-to-date information on research and treatment,
nutrition, alternative therapies, and self-management strategies for patients
with certain autoimmune diseases. Chapters nationwide offer exercise programs,
classes, support groups, physician referral services, and free literature. For
more information, call your local chapter, listed in the white pages of the phone
book, or contact the Arthritis Foundation at the above address.
*
The Hip Society
951 Old County Road, #182
Belmont, CA 94002
Phone: 650–596–6190
Fax: 650–508–2040
Website: http://www.hipsoc.org
This society maintains a list of physicians who are specialists in problems
of the hip, and provides physician referrals by geographic area.
*
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301-495-4484
Toll Free: 877-22-NIAMS (226-4267)
TTY: 301–565–2966
Fax: 301-718-6366
Email: NIAMSinfo@mail.nih.gov
Website: http://www.niams.nih.gov
The NIH Osteoporosis and Related Bone Diseases~National Resource Center provides
patients, health professionals, and the public with an important link to resources
and information on metabolic bone diseases. The mission of NIH ORBD~NRC is to
expand awareness and enhance knowledge and understanding of the prevention, early
detection, and treatment of these diseases as well as strategies for coping with
them. The center provides information on osteoporosis, Paget's disease of bone,
osteogenesis imperfecta, primary hyperparathyroidism, and other metabolic bone
diseases and disorders.
Key Words
Arthroplasty - Another name for total joint replacement, a procedure in which
a damaged joint is surgically removed and replaced with an artificial prosthesis.
It is the treatment of choice for osteonecrosis when the joint is destroyed.
Arthritis - Literally means joint inflammation. It is a general term for
more than 100 of the rheumatic diseases. Arthritis causes joint swelling, pain,
and stiffness.
Asceptic necrosis - See osteonecrosis.
Autoimmune disease - A disease that results when the immune system mistakenly
attacks the body's own tissues.
Avascular necrosis - See osteonecrosis.
Biopsy - A procedure in which tissue is removed from the body and studied
under a microscope. A bone biopsy is a conclusive way to diagnose osteonecrosis.
Blood vessels - Arteries, veins, and capillaries that carry blood through
the body.
Bone graft - The transplantation of healthy bone from one part of the body
to replace injured or diseased bone in another part of the body.
Bone morphogenic protein - A protein extracted from the body and synthesized
through genetic engineering. Research suggests it may be used to promote growth
of bone damaged by osteonecrosis.
Bone scan - A type of test called technetium-99m bone scanning is used most
commonly in patients who have normal x rays and no risk factors for osteonecrosis.
In this test, a harmless radioactive material is injected through an intravenous
line, and a picture of the bone is taken with a special camera. The picture shows
how the injected material travels through blood vessels in bone. A single bone
scan finds all areas in the body that are affected, thus reducing the need to
expose the patient to more radiation.
Cancer - A term for diseases in which abnormal cells divide without control.
Cancer cells can invade nearby tissues and can spread through the bloodstream
and lymphatic system to other parts of the body.
Caisson disease - A syndrome that occurs when deep-sea divers, construction
workers, or others working in a pressurized environment return to normal atmospheric
pressure. Nitrogen in the bloodstream expands to form bubbles, causing pain and
blocking circulation in the small blood vessels. The condition can potentially
lead to osteonecrosis.
Cholesterol - Fat-like material present in the blood and most tissues. High
levels of cholesterol can be a risk factor in the development of osteonecrosis
as well as cardiovascular disease.
Computed (or computerized) tomography (CT) scan - An imaging technique that
provides the doctor with a three-dimensional picture of the bone. It also shows "slices" of
the bone, making the picture much clearer than x rays and bone scans.
Core decompression - A surgical procedure in which the inner layer of the
bone is removed to reduce pressure within the bone, thereby increasing blood
flow to the bone. In people with early osteonecrosis, the procedure may reduce
pain and slow the progression of bone and joint destruction.
Corticosteroids - Powerful anti-inflammatory hormones made naturally in the
body or man-made for use as medicine. Using corticosteroid medications is a risk
factor for developing osteonecrosis.
Electrical stimulation - A procedure in which electromagnetic fields are
set up around the bones or electricity is applied directly to the bones to induce
bone growth. In some centers it has been helpful in treating patients with osteonecrosis
prior to the collapse of the femoral head.
Epiphysis - The end of a bone where it meets another bone or bones to form
a joint.
Femoral head - The round bony protrusion at the end of the thigh bone that
fits into the acetabulum (socket) of the pelvis to form the hip joint. The femoral
head often collapses in advanced osteonecrosis.
Femur - The upper leg, or thigh, bone. The end of the femur, where it meets
the pelvis, is the most common site of osteonecrosis.
Gaucher's disease - A congenital disease in which there is accumulation of
fatty compounds in the liver, spleen, lymph nodes, and nervous system. Having
the disease has been associated with the development of osteonecrosis.
Gout - A type of arthritis caused by the reaction of the body to needle-like
crystals of uric acid that accumulate in joint spaces. This reaction causes joint
inflammation, swelling, and pain in the affected joint, most commonly the big
toe.
HIV (human immunodeficiency virus) - The virus that causes AIDS.
Immune system - A complex network of specialized cells and organs that work
together to defend the body against attacks by "foreign" invaders such
as bacteria and viruses. In some rheumatic conditions, it appears that the immune
system does not function properly and may even work against the body.
Inflammation - A reaction of tissues to injury or disease, marked by four
signs: swelling, redness, heat, and pain.
Ischemic necrosis - See osteonecrosis.
Lupus - Systemic lupus erythematosus (also known as lupus or SLE) is an autoimmune
disease in which the immune system harms the body's own healthy cells and tissues.
This can result in inflammation of and damage to the joints, skin, kidneys, heart,
lungs, blood vessels, and brain.
Magnetic resonance imaging (MRI) - A procedure in which a strong magnet is
used to pass a force through the body to create a clear, detailed image of a
cross-section of the body. MRI detects chemical changes in the bone marrow and
can show osteonecrosis in its earliest stages, often before it causes any symptoms.
Meniscus - A crescent-shaped wedge of cartilage in the knee joint. Tears
of the meniscus have been associated with the development of both osteonecrosis
and osteoarthritis in the knee.
Orthopaedist - A doctor who specializes in diseases of and traumatic injuries
to the bones and musculoskeletal system. Also called orthopaedic surgeon.
Osteoarthritis - A disease in which the cartilage that cushions the ends
of the bones breaks down, leading to joint pain and stiffness. The most common
form of arthritis, osteoarthritis grows more common with age.
Osteonecrosis - A disease in which a temporary or permanent loss of the blood
supply to the bones causes bone tissue to die and the bone to collapse. Also
known as avascular necrosis, aseptic necrosis, and ischemic necrosis.
Osteoporosis - A disease in which the bone loses density and becomes so porous
that it can break as a result of even minor trauma.
Osteotomy - A surgical procedure that involves reshaping the bone to reduce
stress on a diseased or damaged area of a joint. It is often used for patients
with advanced osteonecrosis and those with a large area of affected bone.
Range-of-motion exercises (ROM)- A program of exercises involving
joints affected by arthritis. These exercises may help keep the joint mobile
and increase range of motion.
Sickle cell disease - A hereditary blood disease characterized by the production
of an abnormal type of hemoglobin in the red blood cells. Having the disease
increases one's risk of osteonecrosis.
Vasculitis - A disease in which there is inflammation of the blood vessels.
Having vasculitis may increase one's risk of osteonecrosis.
Acknowledgments
The NIAMS gratefully acknowledges the assistance of Thomas D. Brown, Ph.D.,
of the University of Iowa, Iowa City; Harry E. Rubash, M.D., Asit Shah, M.D.,
and Jeffrey Geller, M.D., all of Massachusetts General Hospital, Boston; and
James Panagis, M.D., M.P.H., NIAMS, NIH in the preparation and review of this
booklet.
The mission of the National Institute of Arthritis and Musculoskeletal and
Skin Diseases (NIAMS), a part of the Department of Health and Human Services'
National Institutes of Health (NIH), is to support research into the causes,
treatment, and prevention of arthritis and musculoskeletal and skin diseases;
the training of basic and clinical scientists to carry out this research; and
the dissemination of information on research progress in these diseases. The
National Institute of Arthritis and Musculoskeletal and Skin Diseases Information
Clearinghouse is a public service sponsored by the NIAMS that provides health
information and information sources. Additional information can be found on the
NIAMS Web site at www.niams.nih.gov/.
For Your Information
This publication contains information about medications used to treat the
health condition discussed here. When this booklet was printed, we included the
most up-to-date (accurate) information available. Occasionally, new information
on medication is released.
For updates and for any questions about any medications you are taking, please
contact the U.S. Food and Drug Administration at:
U.S. Food and Drug Administration
Toll Free: 888-INFO-FDA (888-463-6332)
Website: http://www.fda.gov/
NIH Publication No. 06-4857
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