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Avascular necrosis is the death of bone tissue due to a lack of blood supply. Also called osteonecrosis, Ischemic Bone Necrosis or Asepctic Bone Necrosis.

Avascular necrosis can lead to tiny breaks in the bone and the bone’s eventual collapse.

The blood supply to a section of bone can be interrupted if the bone is fractured or the joint becomes dislocated. such as the femoral head, carpals, talus, and humerus.
The hip is the joint most commonly affected by avascular necrosis.

The amount of disability that results from avascular necrosis depends on several factors:

• What part of the bone is affected

• How large an area is involved &

• How effectively the bone rebuilds itself.

Acute trauma (Fracture or dislocation)

Steroid therapy

Alcoholism

Pancreatitis

Sickle Cell Anemia

Cushing’s disease

Collagen vascular disease (e.g. SLE)

Caisson disease

Gaucher’s disease

Radiation therapy

HIV

Autoimmune Disorders

As many as 20,000 people develop AVN each year. Most are between the ages of 20 and 50. For healthy people, the risk of AVN is small. Most cases are the result of an underlying health problem or injury.

Vascular occlusion: This is characterized by the interruption of the extraosseous blood supply via factors such as direct trauma (eg, fracture, dislocation), nontraumatic stress, and stress fracture.

Altered lipid metabolism: Animal studies have led to the hypothesis that increased levels of serum lipids leads to lipid deposition in the femoral head, causing femoral hypertension and ischemia. Lipid-level–lowering drugs in animals reverse this process. Corticosteroid administration was associated with fat emboli in the femoral heads of rabbits.

Intravascular Coagulation: Disorders of the coagulation system have been implicated in the pathogenesis of AVN. Typically, it is a secondary event triggered by a familial thrombophilia, hypercholesterolemia, allograft organ rejection, other disorders (eg, infection, malignancy), or pregnancy.

Healing process: Necrotic bone triggers a process of repair that includes osteoclasts, osteoblasts, histiocytes, and vascular elements. Osteoblasts build new bone on top of the dead bone, leading to a thick scar that prevents revascularization of the necrotic bone, with resultant abnormal joint remodeling and joint dysfunction.

Primary cell death: Osteocyte death without other features of AVN has been seen in renal transplant patients, as well as in patients receiving steroids and those who consume significant amounts of alcohol.

Mechanical stress: Animal studies have shown an association between increased weight bearing and an increased incidence of AVN of the femoral head.

In the early stages of AVN, patients may not have any symptoms. As the disease progresses, most patients experience joint pain—at first, only when putting weight on the affected joint and later even when resting. Pain usually develops gradually and may be mild or severe.

If avascular necrosis progresses and the bone and surrounding joint surface collapse, pain may develop or increase quickly. Pain may be severe enough to limit the patient’s range of motion in the affected joint.

The period of time between the first symptoms and loss of joint function is different for each patient. It ranges from several months to more than a year.

Early diagnosis of AVN helps to recover from the disease.

X-rays – A radiograph, or x ray, may be the first recommended test. A simple way to produce pictures of bones, an x ray is often useful in diagnosing the cause of joint pain. For AVN, however, x rays are not sensitive enough to detect bone changes in the early stages of the disease.

Magnetic resonance imaging (MRI) scans –MRI detects chemical changes in the bone marrow. MRI provides the picture of the affected area and the bone-rebuilding process. In addition, MRI may show diseased areas that are not yet causing any symptoms.

Computerized Tomography (CT scan) –A CT scan is an imaging technique that provides 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. CT scan is useful in determining the extent of bone damage.

Bone Scan –A bone scan is used most commonly in patients who have normal x rays and no risk factors for AVN. 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.

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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).

Reduced weight bearing: 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 weight bearing can slow the damage caused by osteonecrosis and permit natural healing. When combined with pain medication, reduced weight bearing 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 before femoral head collapse.

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 several 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 several months.

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.

Reduces: marrow edema

Increases O2 Delivery to ischemic cells to relieve the compartment syndrome and preventing further necrosis

Significant Pain Relief: from  marrow pressure (20 txs)

Stimulates Angiogenesis

Stimulates Oxygen Dependent Cells: osteoclast and osteoblast function for remodeling & repair

Stimulates Multi-Potential Fibroblasts in the marrow to become osteogenic and form bone (When the O2 tension is low these cells produce cartilage. )

Reverses the Imbalance

Needs high pressure + 100% O2 under supervision of an expert in HBOT.

Avascular Treatment

Counseling
Diagnosis and Assessment
Pharmacologic Intervention
Assistive Devices
Stem Cell Therapy