By Dr Raghuram Y.S. MD (Ay) & Dr Manasa, B.A.M.S
Avascular means lack of blood supply. Necrosis is death of cells in a tissue or organ, due to disease, injury or lack of blood supply. Avascular necrosis means ‘death of bone tissue’. It happens due to lack of blood supply. Avascular Necrosis is also abbreviated as AVN.
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What is the consequence
When there is lack of blood supply to the bone, small breaks can occur due to death of its tissue. Eventually it may lead to bone collapse.
When a bone breaks or joint gets dislocated, there can cause obstruction of blood flow to a part of bone. The disease usually affects the joints of the body. It may occur on one side or is bilateral (like afflicting both hips, both knee joints etc).
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Synonyms
Osteonecrosis – osteo means bone, necrosis means death
Aseptic necrosis
Ischemic bone necrosis
Osteochondtitis Dissecans
Chandler’s Disease
Who is afflicted by AVN?
AVN is most commonly found to occur in people between 30-50 years age group. But it can affect anyone. Some references tell that most people suffering from AVN are between 20 and 50 years of age.
Symptoms
In many people there may not be any symptoms especially in the earlier stages of the disease.
Pain of AVN – In advanced conditions, the disease becomes worse. In this condition one may experience joint pain.
– At the beginning it might hurt only when you put pressure on the affected bone. Later the pain becomes constant.
– Joint hurts more when more weight is transferred onto the joint. The pain of AVN is also felt when one lies down.
– If there is collapse of bone and surrounding tissue the pain gets severe. In this condition one will not be able to use the joints. The range of movements too will get restricted.
– The time gap between the first symptoms of AVN i.e. pain and bone collapse may range from several months to more than one year.
Nature of the pain – The pain of AVN may be mild or severe in nature. It usually develops gradually.
Common seats of AVN – AVN most commonly occur in the hips. Other sites are shoulder, knee, hand and foot (ankles).
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When to consult the doctor?
– Joint pain is worse, persistent and intolerable
-feeling that your bone has been broken or joints dislocated
Causes
Reduction or interrupted blood supply to a bone is the main cause of avascular necrosis.
Causes of reduction in blood supply to the bone
1. Bone / Joint trauma – caused by –
– dislocation of joint
– damage to bone due to injury
– cancer treatments weaken bones and harm blood vessels since it involves radiation
AVN may affect 20% of people or more in whom hip dislocation takes place.
2. Deposits of fats in blood vessels – which eventually block the small blood vessels. This will reduce the blood flow to the bones and there will be death of bone tissue.
3. Impact of diseases – like sickle cell anemia and Gaucher’s disease may cause reduced blood flow to the bone causing death of bone tissue.
4. Arterial pathology / damage – blood clots, inflammation and damage to arteries can block blood flow to the bones causing AVN.
5. Use of steroids in higher doses for a longer time – 35% of non-traumatic AVN are said to be caused by long term use of steroids. They are believed to increase blood fat deposits leading to hampered blood flow to bones and joints.
6. Excessive consumption of alcohol – might lower blood supply to the bones by causing deposits of fat in the blood / blood vessels.
7. Treatments – radiation therapy for cancer, organ transplants
Note – The cause of disruption of blood supply to the bones is not known in about 25% of people suffering with AVN.
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Risk Factors
Trauma – causes dislocation or fracture and consequent damage to the blood vessels therein. This will cause diminution in blood flow to bones leading to the death of bone tissue.
Excessive use of steroids and alcohol
Certain treatments – like radiation therapy, organ transplantation (mainly kidney) weaken the bones and also cause AVN. Long term use of high doses of Bisphosphonate for treatment of cancers might contribute to osteonecrosis of the jaw.
Medical conditions which might contribute to AVN
– Diabetes
– Sickle Cell Anemia
– Pancreatitis
– SLE (Systemic Lupus Erythematosus)
– HIV / AIDS
– Gaucher’s disease
– Decompression sickness
– Radiation therapy / chemotherapy
– Autoimmune diseases
Complications
– Bone collapse
– Loss of bone shape
– Severe Arthritis
Prevention
– Avoid or limit smoking and drinking alcohol
– Keep a control on cholesterol levels
– Avoid indiscriminate use of steroids in high dose and for longer time
Home Care
Taking good rest – will help to slow down the damage to the joints and will help in their recovery. Alternatively one may use crutches.
Doing exercises in the right way – physical exercises should be done cautiously by taking the help of a doctor or expert therapist. This will help you to get the right moves. You can gradually try to regain good range of motion in your joints.
Diagnosis
The doctor would examine your joints to elicit pain, tenderness and any other damage so as to make appropriate diagnosis. The range of motions may also be examined.
Imaging tests
– X-rays – helps in finding out the bone changes which occur in AVN, in the later stages of the disease.
– MRI & CT Scan – help in finding out the early changes occurring in the bone indicating AVN.
– Bone Scan – helps in finding out the parts of bones that are injured or healing.
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Prognosis
More than half patients who suffer from AVN might need surgery within 3 years of diagnosis of the disease.
If bone collapse occurs in one of the joints, it is likely to happen sooner or later in the other joint also.
The outlook depends on the disease stage at the time of diagnosis and the presence of an underlying condition / disease.
The prognosis will be good if
– patient is over 50 years of age
– disease is at stage III or higher at the time of diagnosis
– there is death of more than 1/3 of the bone’s weight bearing area
– damage has gone past the bone end
– there is a long history of treatments with cortisone
Treatment
The main goal of the treatment will be to prevent the further loss of bone tissue, to improve movements at the joint and ease pain in the joints. Effective treatment depends on the age of the patient, cause of AVN, stage of the disease, amount of damage to the bone & location of disease. If the disease is diagnosed earlier, the treatment may involve limiting the use of the affected joint and taking pain relieving medications.
Medicines and therapy – helps in easing the symptoms of early stages of AVN. They include –
1. NSAID – medicines such as ibuprofen, naproxen sodium etc – helps in relieving pain
2. Drugs used to treat osteoporosis
3. Drugs used for lowering cholesterol levels – They will reduce the cholesterol and fat from the blood. This would help in preventing the blockages in the blood vessels supplying the bones which may cause AVN.
4. Blood thinners – prevents clotting in the blood vessels supplying the bones. These are given even if AVN is caused by blood clots.
5. Rest – reducing physical activity or using crutches would help in keeping the body weight and stress off the joints and bones and slow down the damage.
6. Exercises – will help in maintaining and also improving the range of motions in the joints
7. Electrical stimulation – will help in replacing the damaged bone by enabling the body to grow new bone.
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Surgical procedures and other effective interventions
Core decompression – a part of the inner layer of bone is removed surgically. This procedure reduces pain, healthy bone tissue and blood vessels are produced.
Bone transplant (bone graft) – strengthens the bone area affected by AVN.
Bone reshaping (osteotomy) – from above or below a weight bearing joint, a wedge of bone is removed. This helps to shift the weight off the damaged bone.
Joint replacement – should be done when the diseased bone has collapsed or when other treatments are not yielding the desired results.
Regenerative medicine treatment – For treating early stage of avascular necrosis of the hip, bone marrow aspirate and concentration are appropriate. Stem cells are harvested from the bone marrow. The dead hip bone is removed and the stem cells are placed in its place. This will allow growth of new bone.
Electrical stimulation – will help in stimulating new bone growth.
