Questions

&Answers

about . . .

National Institute of Arthritis and Musculoskeletal and Skin D

National Institutes of Health

Public Health Service • U.S. Department of Health and Huma

Osteonecro

(Avascular Necro
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You can also find this booklet on the NIAMS W

www.niams.nih.gov.

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used to treat the health condition discussed here. 

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What Is Osteonecrosis? . . . . . . . . . . . . . . . . . . . . . 

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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Osteonecrosis is a disease resulting from the temp

permanent loss of blood supply to the bones. Wit

the bone tissue dies, and ultimately the bone may 

the process involves the bones near a joint, it often 

collapse of the joint surface. Osteonecrosis is also 

avascular necrosis, aseptic necrosis, and ischemic 

Although it can happen in any bone, osteonecros

commonly affects the ends (epiphysis) of the fem

extending from the knee joint to the hip joint. Ot

mon sites include the upper arm bone, knees, sho

ankles. The disease may affect just one bone, mor

bone at the same time, or more than one bone at 

times. According to the American Academy of Or

Surgeons, 10,000 to 20,000 people develop osteon

year, and most of them are between 20 and 50 yea

Osteonecrosis is the underlying diagnosis in appr

10 percent of hip replacements. Orthopaedists – d

specialize in the diagnosis and treatment of injur

eases of the musculoskeletal system – most often 

this disease. 

The amount of disability that results from osteon

depends on what part of the bone is affected, how 

area is involved, and how effectively the bone reb

Normally, bone continuously breaks down and re

bone is replaced with new bone. This process – w
minerals. In the course of osteonecrosis, however, 

process is usually ineffective and the bone tissues 

faster than the body can repair them. If left untre

disease progresses, the bone collapses, and the joi

breaks down, leading to pain and arthritis.

What Causes Osteonecrosis?

Osteonecrosis is caused by impaired blood supply 

bone, but it is not always clear what causes that im

Osteonecrosis often occurs in people with certain 

(such as high-dose corticosteroid use and excessiv

intake) and medical conditions. However, it also 

ple with no health problems and for no known re

lowing are some potential causes of osteonecrosis 

health conditions associated with its developmen

Steroid Medications

Aside from injury, one of the most common cause

osteonecrosis is the use of corticosteroid medicati

prednisone. Corticosteroids are commonly used t

inflammatory diseases such as systemic lupus ery

rheumatoid arthritis, inflammatory bowl disease, 

asthma, and vasculitis. Studies suggest that long-

oral or intravenous (IV) corticosteroids is associat

2
Doctors are not sure exactly why the use of cortic

sometimes leads to osteonecrosis. They speculate 

drugs may interfere with the body’s ability to brea

fatty substances called lipids. These substances th

in and clog the blood vessels, causing them to nar

reduce the amount of blood that gets to the bone. 

ies suggest that corticosteroid-related osteonecros

severe and more likely to affect both hips (when o

the hip) than osteonecrosis resulting from other c

Alcohol Use

Excessive alcohol use is another common cause o

osteonecrosis. People who drink alcohol in excess 

develop fatty substances that may block blood ves

ing a decreased blood supply to the bones.

Injury

When a fracture, a dislocation, or some other join

occurs, the blood vessels may be damaged. This c

with the blood circulation to the bone and lead to 

related osteonecrosis. In fact, studies suggest that 

tion and hip fractures are major risk factors for os

Increased pressure within the bone may be anoth

osteonecrosis. When there is too much pressure w
increased pressure is not fully understood. 

Other Risk Factors

Other risk factors for osteonecrosis include radiat

chemotherapy, and organ transplantation (particu

ney transplantation). Osteonecrosis is also associa

number of medical conditions, including cancer, 

blood disorders such as sickle cell disease, HIV in

Gaucher’s disease, Caisson disease, gout, vasculit

osteoarthritis, and osteoporosis. 

Who Is Likely to Develop Osteonecrosis? 

Osteonecrosis affects both men and women. It ca

people of any age, from children to the elderly. H

most common in people in their thirties, forties, a

What Are the Symptoms?

In the early stages of osteonecrosis, people may n

symptoms. As the disease progresses, however, m

ence joint pain. At first, the pain occurs only whe

weight on the affected joint. Later, it occurs even 

ing. Pain usually develops gradually, and may be 

severe. If osteonecrosis progresses and the bone an

rounding joint surface collapse, pain may develop 

4
those involving the hip, disabling osteoarthritis m

develop. The period of time between the first sym

and loss of joint function is different for each pers

typically ranges from several months to more than 

How Is Osteonecrosis Diagnosed?

After performing a complete physical examinatio

asking about the patient’s medical history, the do

use one or more bone imaging techniques to diag

osteonecrosis. As with many other diseases, early 

increases the chances of treatment success. The te

described below may be used to determine the am

bone affected and how far the disease has progres

X Ray

A radiograph, or x ray, is probably the first test the 

will recommend. A simple way to produce pictur

bones, an x ray is often useful in diagnosing the c

joint pain. For osteonecrosis, however, x rays are n

tive enough to detect bone changes in the early st

the disease. So if the x ray is normal, the doctor m

more tests. In later stages of osteonecrosis, x rays m

bone damage, and once the diagnosis is made, th

often used to monitor disease progression.
g

imaging, or MRI, is the most sensitive method for 

ing osteonecrosis in the early stages. Unlike x rays

scans, and CT (computed/computerized tomogra

scans (see below), MRI detects chemical changes 

bone marrow. MRI provides the doctor with a pic

affected area and the bone-rebuilding process. In 

MRI may show diseased areas that are not yet cau

symptoms. Some doctors caution against aggressi

ment of osteonecrosis that has been detected by M

not causing symptoms. One study has shown evid

for a select group of patients in the early stages of

osteonecrosis, the disease may improve spontaneo

Computed/Computerized Tomography (CT scan)

A CT scan is an imaging technique that provides 

with a three-dimensional picture of the bone. It a

“slices” of the bone, making the picture much cle

x rays and bone scans. Some doctors disagree abo

fulness of this test to diagnose osteonecrosis. Alth

diagnosis usually can be made without a CT scan

nique may be useful in determining the extent of 

damage. CT scans are less sensitive than MRIs.

6
yp

most commonly in patients who have normal x ra

risk factors for osteonecrosis. In this test, a harmle

tive material is injected through an intravenous li

picture of the bone is taken with a special camera

ture shows how the injected material travels throu

vessels in bone. A single bone scan finds all areas 

body that are affected, thus reducing the need to e

patient to more radiation.

Biopsy

A biopsy is a surgical procedure in which a tissue 

from the affected bone is removed and studied. A

biopsy is a conclusive way to diagnose osteonecro

rarely used because it requires surgery.

Functional Evaluation of Bone

Tests to measure the pressure inside a bone may b

when the doctor strongly suspects that a patient h

osteonecrosis, despite normal results of x rays, bon

and MRIs. These tests are very sensitive for detec

increased pressure within the bone, but they requ
Appropriate treatment for osteonecrosis is necessa

joints from breaking down. Without treatment, m

with the disease will experience severe pain and l

in movement within 2 years. To determine the m

priate treatment, the doctor considers the followin

• the age of the patient

• the stage of the disease (early or late)

• the location and whether bone is affected 

small or large area

• the underlying cause of osteonecrosis. Wit

ongoing cause such as corticosteroid or alc

treatment may not work unless use of the 

is stopped.

The goal in treating osteonecrosis is to improve th

use of the affected joint, stop further damage to th

and ensure bone and joint survival. To reach thes

the doctor may use one or more of the following s

nonsurgical treatments.

Nonsurgical Treatments

Usually, doctors will begin with nonsurgical treat

alone or in combination. Unfortunately, although 

8
• Medications – Nonsteroidal anti-inflamm

(NSAIDs) are often prescribed to reduce p

with clotting disorders may be given blood 

reduce clots that block the blood supply to 

Cholesterol-lowering medications may be 

reduce fatty substances (lipids) that increa

ticosteroid treatment (a major risk factor f

osteonecrosis). In one study, people who to

terol-lowering medications called statins a

corticosteroids significantly reduced the ri

oping osteonecrosis in the first place. 

• Reduced weightbearing – If osteonecrosis 

nosed early, the doctor may begin treatmen

the patient remove weight from the affecte

The doctor may recommend limiting activ

using crutches. In some cases, reduced we

can slow the damage caused by osteonecro

mit natural healing. When combined with 

ication, reduced weightbearing can be an 

way to avoid or delay surgery for some pat

• Range-of-motion exercises – An exercise 

involving the affected joints may help keep 

mobile and increase their range of motion
some studies has been helpful when used 

femoral head collapse. 

Surgical Treatment

A number of different surgical procedures are use

osteonecrosis. Most people with osteonecrosis wil

need surgery.

• Core decompression – This surgical proce

removes the inner cylinder of bone, which 

pressure within the bone, increases blood 

bone, and allows more blood vessels to for

decompression works best in people who a

earliest stages of osteonecrosis, often befor

lapse of the joint. This procedure sometim

pain and slows the progression of bone an

destruction. 

• Osteotomy – This treatment involves resh

bone to reduce stress on the affected area. 

can be a lengthy process, requiring 3 to 12 

very limited activities. This procedure is m

tive for patients with early-stage osteonecr

those with a small area of affected bone. 

• Bone graft – This is the transplantation of 

bone from another part of the body. It is of

10
graft – which includes an artery and vein 

increase the blood supply to the affected a

ery from a bone graft can take from 6 to 12 

The procedure is complex and its effective

unproven. Clinical studies are underway t

its effectiveness. 

• Arthroplasty/total joint replacement – To

replacement is the treatment of choice in l

osteonecrosis and when the joint is destroy

surgery, the diseased joint is replaced with 

parts. Total joint replacement, or sometim

head resurfacing, is often recommended fo

for whom other efforts to preserve the join

failed. Various types of replacements are av

and people should discuss specific needs w

doctor.

For most people with osteonecrosis, treatment is a

process. Depending upon the stage of the disease

may first recommend the least complex or nonop

treatment plans, such as medication or reduced w

ing. If these modalities are unsuccessful, surgical 

may be needed. It is important that patients caref

instructions about activity limitations and work c

their doctors to ensure that appropriate treatment
With proper treatment, most people with osteone

lead productive lives. But there is still a lot to lear

prevention, diagnosis, and treatment. Some goals 

research are to:

• better understand how many people are af

osteonecrosis by screening at-risk populati

MRI (magnetic resonance imaging)

• identify risk factors 

• determine if genetic clotting disorders are 

for developing osteonecrosis in at-risk pop

• identify and/or develop new ways to diagn

osteonecrosis in its earliest stages, when n

treatment is most likely to help

• determine whether biological therapies, su

recombinant human bone morphogenic p

effective treatments for osteonecrosis

• develop new treatments and improve avai

ments for osteonecrosis

• study key mechanical factors – such as the 

of the hips, knees, and ankles – that influe

ment outcomes 

12

Musculoskeletal

harge)

various forms of

one, muscle,
• improve hip replacement techniques and 

so that younger patients will not need mor

hip replacement in their lifetime

• better understand the body’s reaction to s

why taking steroids increases a person’s ri

oping osteonecrosis.

Where Can People Find More Information 

Osteonecrosis?

■ National Institute of Arthritis and Musculos

and Skin Diseases (NIAMS)

National Institutes of Health

1 AMS Circle

Bethesda, MD 20892–3675

Phone: 301–495–4484 or 

877–22–NIAMS (226–4267) (free of charge)

TTY: 301–565–2966

Fax: 301–718–6366

E-mail: NIAMSInfo@mail.nih.gov

www.niams.nih.gov

NIAMS provides information about various f

arthritis and rheumatic disease and bone, mu

and skin diseases. It distributes patient and pr

education materials and refers people to other 
■ American Academy of Orthopaedic Surgeons

P.O. Box 1998

Des Plaines, IL 60017 

Phone: 800–824–BONE (2663) (free of charg

www.aaos.org

The academy is the professional society of bon

surgeons. It seeks to further knowledge in the 

and treatment of bone-related diseases. The a

publishes brochures on total joint replacemen

arthroscopy, and other subjects. Single copies 

brochure are available free of charge by sendin

addressed, stamped (business-size) envelope t

brochure) at the address above.

■ National Osteonecrosis Foundation

Good Samaritan Professional Building

Suite 201

5601 Loch Raven Blvd.

Baltimore, MD 21239

Phone: 410–532–5985

Fax: 410–532–5908

www.nonf.org

The foundation offers brochures, information 

ease, and a physician-finding tool on its Web 

14
Atlanta, GA 30357–0669

Phone: 404–872–7100 or 800–568–4045 (free 

or call your local chapter (listed in the telephon

www.arthritis.org

The Arthritis Foundation is the major volunta

zation devoted to supporting arthritis research 

viding educational and other services to indiv

arthritis. It publishes free pamphlets and a ma

members on all types of arthritis. It also provi

date information on research and treatment, n

alternative therapies, and self-management st

patients with certain autoimmune diseases. C

nationwide offer exercise programs, classes, su

groups, physician referral services, and free lit

more information, call your local chapter, liste

white pages of the phone book, or contact the 

Foundation at the above address.

■ The Hip Society

951 Old County Road, #182 

Belmont, CA 94002

Phone: 650–596–6190

Fax: 650–508–2040

www.hipsoc.org 

This society maintains a list of physicians who 

cialists in problems of the hip, and provides p

referrals by geographic area.
2 AMS Circle

Bethesda, MD 20892–3676

Phone: 202–223–0344 or 800–624–BONE (fre

TTY: 202–466–4315 

Fax: 202–293–2356

E-mail: NIAMSBoneInfo@mail.nih.gov

www.osteo.org

The NIH Osteoporosis and Related Bone Dis

National Resource Center provides patients, h

professionals, and the public with an importa

resources and information on metabolic bone 

The mission of NIH ORBD~NRC is to expa

ness and enhance knowledge and understand

prevention, early detection, and treatment of t

diseases as well as strategies for coping with th

center provides information on osteoporosis, P

disease of bone, osteogenesis imperfecta, prim

parathyroidism, and other metabolic bone dis

disorders.

16
Arthroplasty – Another name for total joint repla

procedure in which a damaged joint is surgically 

and replaced with an artificial prosthesis. It is the 

of choice for osteonecrosis when the joint is destr

Arthritis – Literally means joint inflammation. It 

term for more than 100 of the rheumatic diseases

causes joint swelling, pain, and stiffness. 

Asceptic necrosis – See osteonecrosis.

Autoimmune disease – A disease that results whe

immune system mistakenly attacks the body’s ow

Avascular necrosis – See osteonecrosis.

Biopsy – A procedure in which tissue is removed 

body and studied under a microscope. A bone bio

conclusive way to diagnose osteonecrosis.

Blood vessels – Arteries, veins, and capillaries tha

blood through the body.

Bone graft – The transplantation of healthy bone 

part of the body to replace injured or diseased bon

another part of the body.
suggests it may be used to promote growth of bon

by osteonecrosis.

Bone scan – A type of test called technetium-99m 

ning is used most commonly in patients who hav

x rays and no risk factors for osteonecrosis. In this 

harmless radioactive material is injected through 

venous line, and a picture of the bone is taken wi

camera. The picture shows how the injected mate

through blood vessels in bone. A single bone scan 

areas in the body that are affected, thus reducing 

expose the patient to more radiation.

Cancer – A term for diseases in which abnormal 

without control. Cancer cells can invade nearby t

can spread through the bloodstream and lymphat

other parts of the body.

Caisson disease – A syndrome that occurs when 

divers, construction workers, or others working in 

ized environment return to normal atmospheric p

Nitrogen in the bloodstream expands to form bub

ing pain and blocking circulation in the small blo

The condition can potentially lead to osteonecros

18
the development of osteonecrosis as well as cardio

disease.

Computed (or computerized) tomography (CT) 

imaging technique that provides the doctor with 

dimensional picture of the bone. It also shows “sl

bone, making the picture much clearer than x ray

scans.

Core decompression – A surgical procedure in w

inner layer of the bone is removed to reduce press

the bone, thereby increasing blood flow to the bon

ple with early osteonecrosis, the procedure may re

and slow the progression of bone and joint destru

Corticosteroids – Powerful anti-inflammatory ho

made naturally in the body or man-made for use 

cine. Using corticosteroid medications is a risk fac

developing osteonecrosis.

Electrical stimulation – A procedure in which el

netic fields are set up around the bones or electric

applied directly to the bones to induce bone grow

centers it has been helpful in treating patients wit

osteonecrosis prior to the collapse of the femoral h
Femoral head – The round bony protrusion at th

thigh bone that fits into the acetabulum (socket) 

to form the hip joint. The femoral head often coll

advanced osteonecrosis.

Femur – The upper leg, or thigh, bone. The end 

femur, where it meets the pelvis, is the most comm

osteonecrosis.

Gaucher’s disease – A congenital disease in whic

accumulation of fatty compounds in the liver, spl

nodes, and nervous system. Having the disease h

associated with the development of osteonecrosis

Gout – A type of arthritis caused by the reaction o

to needle-like crystals of uric acid that accumulat

spaces. This reaction causes joint inflammation, s

and pain in the affected joint, most commonly th

HIV (human immunodeficiency virus) – The v

causes AIDS.

Immune system – A complex network of speciali

and organs that work together to defend the body 

attacks by “foreign” invaders such as bacteria and 

some rheumatic conditions, it appears that the im

tem does not function properly and may even wo

the body.

20
Ischemic necrosis – See osteonecrosis.

Lupus – Systemic lupus erythematosus (also kno

or SLE) is an autoimmune disease in which the i

system harms the body’s own healthy cells and tis

can result in inflammation of and damage to the 

kidneys, heart, lungs, blood vessels, and brain.

Magnetic resonance imaging (MRI) – A procedu

a strong magnet is used to pass a force through th

create a clear, detailed image of a cross-section of 

MRI detects chemical changes in the bone marro

show osteonecrosis in its earliest stages, often befo

any symptoms.

Meniscus – A crescent-shaped wedge of cartilage 

joint. Tears of the meniscus have been associated 

development of both osteonecrosis and osteoarthr

knee. 

Orthopaedist – A doctor who specializes in disea

traumatic injuries to the bones and musculoskele

Also called orthopaedic surgeon. 

Osteoarthritis – A disease in which the cartilage 

ions the ends of the bones breaks down, leading t

and stiffness. The most common form of arthritis

osteoarthritis grows more common with age. 
tissue to die and the bone to collapse. Also known 

cular necrosis, aseptic necrosis, and ischemic necr

Osteoporosis – A disease in which the bone loses 

and becomes so porous that it can break as a resu

even minor trauma.

Osteotomy – A surgical procedure that involves r

ing the bone to reduce stress on a diseased or dam

area of a joint. It is often used for patients with ad

osteonecrosis and those with a large area of affect

Range-of-motion exercises – A program of exerc

involving joints affected by arthritis. These exerci

help keep the joint mobile and increase range of m

Sickle cell disease – A hereditary blood disease ch

ized by the production of an abnormal type of he

bin in the red blood cells. Having the disease incr

one’s risk of osteonecrosis.

Vasculitis – A disease in which there is inflamma

the blood vessels. Having vasculitis may increase 

risk of osteonecrosis. 

22
The NIAMS gratefully acknowledges the assistance of Thomas D. B

the University of Iowa, Iowa City; Harry E. Rubash, M.D., Asit Sha

Jeffrey Geller, M.D., all of Massachusetts General Hospital, Boston; 

Panagis, M.D., M.P.H., NIAMS, NIH in the preparation and review 

The mission of the National Institute of Arthritis a

Musculoskeletal and Skin Diseases (NIAMS), a pa

the Department of Health and Human Services’ N

Institutes of Health (NIH), is to support research i

the causes, treatment, and prevention of arthritis a

musculoskeletal and skin diseases; the training of b

and clinical scientists to carry out this research; an

dissemination of information on research progress 

these diseases. The National Institute of Arthritis a

Musculoskeletal and Skin Diseases Information C

house is a public service sponsored by the NIAMS 

provides health information and information sour

Additional information can be found on the NIAM

Web site at www.niams.nih.gov.
U.S. Department of Health and Human Services

Public Health Service

National Institutes of Health

National Institute of Arthritis and 

Musculoskeletal and Skin Diseases

NIH Publication No. 06–4857

January 2001

Revised March 2006