Avascular necrosis of the hip (also called osteonecrosis) means part of the ball at the top of your thighbone has lost its blood supply. Without blood, like anything living, including ourselves…that patch of bone slowly dies, weakens and can eventually cave in.
Caught EARLY, while the ball is still round, surgery to save your own hip is often possible. Once the ball has collapsed, the answer is usually a hip replacement, and modern replacements do well for this condition.
That’s why deep groin pain in a younger adult, especially one with a known risk factor, deserves a proper look and not just a wait-and-see.
Symptoms
- Nothing at first: early on, many people have no pain at all. It’s sometimes found on a scan done for something else
- Groin pain: a deep ache or throb in the groin, sometimes the buttock or thigh
- Pain on weight bearing: worse when you stand and walk, easing with rest at first
- Pain at rest and at night as it progresses
- A limp and a stiffer hip once the ball starts to lose its shape
It tends to affect younger adults than ordinary hip arthritis, and it often affects BOTH hips, even if only one hurts.
What causes it
Often there’s a clear link. In a good share of people, no cause is ever found.
- Steroid medicines: high doses or long courses of corticosteroid tablets or drips, often needed for asthma, lupus, rheumatoid arthritis, transplants or cancer treatment. This is one of the most common links. Never stop a steroid on your own; talk to the doctor who prescribed it
- Heavy alcohol use over years: it can leave fatty deposits that block the small blood vessels feeding the bone
- Hip injury: a hip fracture or dislocation can tear the blood vessels to the ball
- Medical conditions: sickle cell disease, lupus, clotting disorders, Gaucher disease, pancreatitis and HIV
- Other treatments and exposures: radiation therapy, organ transplants, and decompression sickness in divers
Early vs late stages
Doctors grade it in stages. What matters most to you is one question: has the ball collapsed yet?
- Early (before collapse): the X-ray can look NORMAL. An MRI scan is what picks it up. The ball is still round and the joint surface is intact
- Collapse: the dead bone gives way and a crack or flattening appears under the cartilage. Pain usually jumps up here
- Late: the ball is out of shape and the socket starts to wear too. This is now arthritis
- Speed: it can take months to years to move through the stages. Without treatment, most painful hips do eventually collapse
- Size and position matter: a small patch away from the weight-bearing part of the ball is less likely to collapse than a large one
With avascular necrosis, the calendar matters. A round ball can often be saved. A collapsed one usually can’t.
Treatment in the early stages
- Core decompression: the surgeon drills one or more narrow channels into the dead area of the ball. This lowers pressure inside the bone and encourages new blood vessels to grow in. It works best for small or medium patches, before collapse
- Bone grafting: bone or bone-forming cells are often packed into the channel to support the weakened area. Some centers use a graft with its own blood supply taken from the lower leg
- Osteotomy: in selected younger patients, the thighbone is cut and turned so a healthy part of the ball takes the load
- Crutches after surgery: most surgeons limit how much weight you put through the leg for some weeks. See weight bearing after surgery
- Watching and waiting: for small, painless patches, some surgeons monitor with repeat scans rather than operate
Crutches alone, without surgery, may ease pain but don’t reliably stop the ball collapsing. Your surgeon’s plan comes first; ask what stage you’re at and what they’re trying to prevent.
When hip replacement is the answer
- After collapse, or when the joint has become arthritic, a total hip replacement is the usual treatment
- It’s common: in the US, roughly 1 in 10 hip replacements is done for avascular necrosis
- Results are good. Older implants did less well in this group. Modern hip replacements give people with avascular necrosis strong pain relief and lasting results
- Recovery is the same as for arthritis: walking on day one, strength work for months. See hip replacement recovery week by week
- Timing is your call, with your surgeon, based on how much the hip is costing you. See when is it time for a hip replacement
What helps while you wait
- Follow the weight-bearing advice you’re given. If your surgeon wants you on crutches, use them
- Keep the hip moving with gentle range-of-motion work, cycling or water exercise, within pain
- Keep the muscles strong: buttock and thigh strength now makes any later surgery easier to recover from
- Address the risk factors you can: ask your doctor whether your steroid dose can be reviewed, and cut back on alcohol if it’s part of the picture
- Ask about the other hip and other joints if you have ongoing risk factors
Get seen today if
- You can suddenly no longer put weight on the leg, especially after a fall or a sharp jolt of pain
- The hip is hot, swollen and very painful and you have a fever or feel unwell
- You have sickle cell disease and severe new hip or bone pain
Get it checked if
- You’ve had deep groin pain for more than a few weeks and have taken high-dose steroids, drink heavily, or have had a hip injury
- Your X-ray was normal but the pain isn’t settling. Ask whether an MRI is needed
- You’ve been diagnosed in one hip and the other hip starts to ache
- Pain has changed from mainly walking to waking you at night
Find it while the ball is still round, and you keep more of your choices.