AVN Causes: Why Blood Supply to the Hip Bone Fails
The ball of your hip joint, the femoral head, is fed by a few small, delicate blood vessels. If those vessels get blocked or damaged, the bone cells inside start to die. That is Avascular Necrosis (AVN). Understanding why the blood supply failed helps your doctor treat you better and protect your other hip.
Long-term steroid use: the most common cause in India
Corticosteroid medicines (like prednisolone or dexamethasone) save lives in asthma, autoimmune diseases, kidney disease, and severe COVID. But taken in high doses or for long periods, they change how the body handles fat. Tiny fat droplets can clog the small vessels of the femoral head, and steroids also make bone cells more fragile.
Important: Never stop a prescribed steroid on your own, sudden stopping can be dangerous. If you are worried about AVN risk, discuss it with your treating doctor. If you have taken steroids and now have hip pain, get an MRI without delay.
Heavy alcohol consumption
Years of regular heavy drinking raise fat levels in the blood and cause fatty deposits inside the small vessels that feed the hip bone. Slowly, the blood flow chokes off. Alcohol-related AVN is one of the most common patterns we see in Indian men aged 30–50.
Injury or trauma to the hip
A hip fracture or dislocation can physically tear the blood vessels running along the neck of the thigh bone. When this happens, part of the femoral head can lose its supply instantly. AVN can appear months or even a couple of years after the injury, so hip pain after an old accident should never be ignored.
Medical conditions and treatments
- Sickle cell disease: abnormal, sickle-shaped blood cells jam inside small vessels and block flow. This is a major cause of AVN in some Indian communities.
- Lupus (SLE) and other autoimmune diseases, both the disease and the steroids used to treat it raise risk.
- Organ transplant: anti-rejection medicines increase AVN risk.
- Radiation therapy and chemotherapy: can weaken bone and its blood vessels.
- Deep-sea diving (decompression sickness): a rare cause. Gas bubbles block vessels.
Smoking
Nicotine narrows blood vessels and damages their inner lining. Smokers develop AVN more often, progress faster, and respond less well to joint-saving treatment. Quitting genuinely improves your odds at every stage.
Post-COVID complications
After the pandemic, Indian orthopedic centres reported a wave of new AVN cases. Two reasons: high-dose steroids used to treat severe COVID, and the virus's own tendency to increase clotting in small blood vessels. If you were hospitalised for COVID and treated with steroids, treat any new hip or groin pain as a warning sign.
Idiopathic AVN: when no cause is found
In up to one-third of patients, no cause is ever identified. Doctors call this idiopathic AVN. The treatment path is the same, what matters most is the grade at diagnosis, not the cause.
Can I reduce my risk?
- Use steroids only as prescribed, at the lowest effective dose, and review long courses with your doctor
- Keep alcohol well within safe limits, or stop entirely
- Stop smoking
- Manage conditions like sickle cell disease and lupus closely
- Take hip injuries seriously, follow up if pain lingers
- If you have any risk factor plus hip pain, get an MRI early
Learn what to do next in our complete AVN treatment guide, or check whether your symptoms match the early signs of AVN.
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AVN Causes: Frequently Asked Questions
How much steroid use causes AVN?
There is no fixed safe limit, risk rises with higher doses and longer courses, and some people develop AVN even after short high-dose courses. If you have taken steroids for months for asthma, arthritis, skin disease, or during COVID treatment, and now have hip pain, get an MRI. Never stop a prescribed steroid on your own; talk to your doctor.
Can drinking alcohol occasionally cause AVN?
Occasional light drinking is not a known cause. The risk comes from regular heavy drinking over years, which causes fat deposits that block the small vessels feeding the femoral head. The more and the longer you drink, the higher the risk.
Why did COVID treatment cause AVN in some patients?
Severe COVID was often treated with high-dose steroids, which are a leading cause of AVN. The virus itself may also have increased blood clotting in small vessels. Cases of hip AVN appearing months after COVID hospitalisation have been widely reported in India. If you received COVID steroids and have hip pain, get checked early, see the symptoms to watch for.
Can AVN happen with no cause at all?
Yes. In up to a third of cases no clear cause is found. Doctors call this idiopathic AVN. It is treated the same way as other AVN, the grade at diagnosis matters more than the cause.
If I remove the cause, will my AVN heal by itself?
Stopping the cause (alcohol, smoking) slows the damage and is strongly advised, but bone that has already lost blood supply rarely heals fully on its own. Early-stage AVN still needs active treatment, regenerative therapy, protected weight bearing, and monitoring, to save the joint.
Know Your Risk. Act Before the Damage Grows.
If you have a risk factor and hip pain, an early MRI can save your natural hip. Talk to us for a free, no-obligation consultation.
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