More info on Osteonecrosis

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Osteonecrosis is a disease coming from the interruption of the blood

supply to the bones. Without blood, the bone tissue dies and starts

to

be destroyed. This disease also is known as avascular

necrosis(AVN),

aseptic necrosis, and ischemic bone necrosis.

Although

osteonecrosis can happen in any bone, it most

commonly

affects the femoral head. The disease may affect just one bone,

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

different times. Osteonecrosis usually affects

people between

30 and

50 years of age.

The

amount of disability that results from osteonecrosis

depends

on what portion of the femoral head is affected, how big the

involved

lesion is , and how effectively the bone regenerate itself.

If left untreated,

osteonecrosis of femoral head progresses in most of the cases

and the femoral head collapses, leading to pain and

arthritis.

Osteonecrosis affects both men and women

of all ages.

Depending on a person's risk

factors and whether the underlying

cause is trauma, it also can affect younger or older people.

It is more common in young

males. In about 60 to 70 % of patients,

the disease is bilateral. Osteonecrosis

of the femoral head has a

male:female ratio of 4 to 5:1. The peak incidence is between ages

30 and

60. Usually the patient is

below the age 50.

What

Causes Osteonecrosis of Femoral Head?

Osteonecrosis has several causes. Loss of blood supply to the

bone can be

caused by an injury(traumatic osteonecrosis) or

by

certain risk factors (non-traumatic avascular

necrosis), such as

some

medications (steroids) or excessive alcohol use.

1) Injury

When

a hip joint is injured, as in a fracture or dislocation,

the blood

vessels may be damaged. This can interfere with the

blood

circulation to the bone and lead to trauma-related osteonecrosis.

Studies suggest

that this type of osteonecrosis may develop in more

than 20

percent of people who dislocate their hip joint.

2) Steroid

Medications

Corticosteroids

such as prednisone are commonly used to

treat diseases

in which there is inflammation, such as systemic

lupus erythematosus, rheumatoid arthritis, and vasculitis. Long-term,

systemic corticosteroid use is known to be associated with

about

35 percent of all cases of non-traumatic osteonecrosis.

We are not sure

about the exact mechanism why the use of

corticosteroids sometimes lead to osteonecrosis.

3) Alcohol

overuse

Excessive

alcohol use is another known risk factor to

cause

non- traumatic osteonecrosis. In people

who drink

an

excessive amount of alcohol, fatty substances may block

blood vessels causing

a decreased blood supply to the bones

that results

in osteonecrosis.

4) Other Risk

Factors

Other

risk factors or conditions associated with non-traumatic

osteonecrosis include Gaucher's disease, pancreatitis, radiation

treatments and chemotherapy, decompression disease, and blood

disorders such as sickle cell disease.

3) What Are the Symptoms?

In the early stages of osteonecrosis, patients may not

have any symptoms. As the disease progresses, however,

most patients experience joint pain first, only when putting

weight on the affected joint, and then even when resting.

If osteonecrosis progresses and the bone and surrounding

joint surface collapses, pain may develop or increase dramatically.

Pain may be severe enough to

limit the patient's range of motion in

the affected joint. Limping is another important symptome

due to this disease.

The period of time between the

first symptoms

and loss of joint function is different for each patient, ranging from

several months to more than a year.

4) How Is Osteonecrosis

Diagnosed?

As with many

other diseases, early diagnosis increases the

chances of treatment success. After taking

the patient's medical

history and performing a physical examination,

I usually

recommend two or three imaging techniques to diagnose

osteonecrosis such as x-rays, MRI and bone scan.

1) X-Ray (Radiography)

The

x-ray of a person with early osteonecrosis is likely

to be

normal initially. The x-rays shows mixed density

-increased and decreased density- with lapse of time.

Then the femoral

head starts to collapse with narrowing of the

joint space.

At the terminal stage, the hip joint takes the

appearance of advanced osteoarthritis.

2) Magnetic

Resonance Imaging (MRI)

MRI

has become a common method for diagnosing osteonecrosis.

Unlike x-rays,

bone scans, and computerized tomography scans,

MRI detects

chemical changes in the bone marrow and can show

osteonecrosis in the earliest stages. MRI provides the doctor with

a picture

of the area affected and the bone rebuilding process.

3) Bone Scintigraphy (Bone Scan)

A

harmless radioactive dye is injected intravenously and a

picture of the bone is taken with a special camera. The picture

shows where normal bone formation is occurring. Sometimes

bone scans

detect osteonecrosis earlier than MRI.

Bone

scan often shows increased uptake around the necrotic bone.

This represents acumulation of radionuclide in the area of increased

bone

turnover, at the junction between dead and reactive bone.

Pinhole bone scintigraphy of the hip captures better images than

whole body

bone scan. It oftentimes is very helpful to evaluate the

healing process after vascularized bone

grafting into the femoral head.

4)

Computed/Computerized Tomography (CT)

A CT scan is an imaging technique that provides the doctor

with a

two-dimensional or 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 avascular

necrosis. Although

a

diagnosis usually can be made without a CT scan, the technique

sometimes is useful in determining the extent of bone damage.

5) Biopsy

A

biopsy is a surgical procedure in which tissue from the affected

bone is removed

and studied with a microscope to watch the pathologic

process if the bone cells are alive or dead. Although a biopsy is a

conclusive way to diagnose osteonecrosis, it

is rarely used because

it requires

surgery.

5)

What Treatments Are

Available?

Appropriate treatment for osteonecrosis is necessary to keep

the femoral head from destruction. If untreated, most patients

will suffer severe pain and limitation in movement within 2 years.

Only patients with very small

lesion can last more than two years.

Several treatments are available

that can help prevent further bone

and joint damage and reduce pain.

To

determine the most appropriate treatment, the doctor considers

the following aspects: patient's age, stage of disease,

location of necrotic lesion, and extent of bone affected.

The goal

in treating osteonecrosis is to improve the patient's

joint function, 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 treatments:

1) Protected Weight Bearing:

Canes,

crutches or a walker can be used to reduce the pain

prevent collapse associated with osteonecrosis. But

this is used usually

between the time of diagnosis and scheduling of elective surgery.

Even though

protected weight bearing theoretically can slow the damage

caused by osteonecrosis most patients eventually

need a surgery,

either femoral head preserving operation or replacement surgery.

Rarely, an associated medical

condition may result in a patient not being

able to receive surgery. In this situation, protected weight bearing may

be recommended for pain management or for protection of further collapse

temporarily.

2) Core Decompression or Multiple drilling

This

surgical procedure removes a pug of bone, which reduces

pressure within the bone and therefore reduces pain.

Many studies reported good

results only for mild to moderate degree

of involvement that has not progressed to collapse. However a

few recent studies reported poor results after core decompression.

Advocates for this procedure say

that this procedure increases

blood flow to the bone and allows more blood vessels to form.

However, no reports

show a clear evidence representing

revascularization into the avascular area grahically.

3) Osteotomy

The usual

location of necrotic area bears weight because the

frequent site is anterosuperior portion of femoral

head. In some

cases, the proximal bone can be cut and rotated or turned so

that healthy portion of the femoral head goes superiorly and bears

weight. Intertrochanteric varus

osteotomy or transtrochanteric

rotational

osteotomy is an example. These procedures may be performed in

cases with smaller lesions in an appropriate location.

4) Non-vascularized

Bone Grafting

This

method simply removes the dead bone surgically and fill the

empty space with bone graft that is either taken from the patient

(ilium, tibia, fibular etc) or from the bone bank.

However, as grafted

bone is also a dead bone, it serves as a scaffold for the body to

build new bone. With the development of vascularized

bone graft,

this procedure has become less popular.

5) Vascularized

Bone Grafting

In this

procedure, the dead bone is removed from the femoral

head and replaced with the grafted bone that carries with its own

blood supply. Theoretically and empirically I believe this kind of

procedure is the best option for osteonecrosis of

femoral head.

In free vascularized

fibular grafting, the artery and vein is anastomosed

microscopically after grafting a segment of fibula into the femoral head.

Vascularized iliac grafting supplies blood through deep or superficial

circumflex iliac artery, or through muscle pedicle with a segment of ilium

grafted into the femoral head. it is an established

fact that vascularized

bone grafting accelerates the bone healing much faster than

non-vascularized bone

grafting. Shortening of healing time is very

important to prevent further collapse of femoral head.

6) Arthroplasty

Total

hip 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. It may be recommended

for people who are not good candidates for other treatments,

such as patients who do not do well with repeated attempts to

preserve the joint. Various types of replacements are available such

as femoral head resurfacing, Femoral head replacement,

Bipolar hemiarthroplasty,

Metal on metal resurfacing and total hip arthroplasty.

The

femoral head should be preserved as much as possible

especially for young patients. No artificial joint lasts for the lifetime.

The current issue in total hip arthroplasty is bone loss coming from

osteolysis and stress shielding. Osteolysis is developed

by the tissue

reaction to wear particles which were generated from the articficial

joint.

The stress shielding comes from

avoidance of normal physiological loading

to bone which is necessary for normal development. Many efforts to prevent

these problems are being made. Polyethylenes of

better quality(so called

Cross-linked Polyethylene), ceramic on ceramic and metal on metal articulations

are

currently used to decrease these

problems.

Much

Love,

Deanna

LUPUS

Serenity Prayer...

Lord, grant me the

serenity to accept the things I cannot change, the courage to change the things

I can, and the wisdom to hide the bodies of doctors I shot when they said,

You're perfectly healthy, it's all in your head "