Avascular Necrosis of the Hip (AVN) & Core Decompression

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Avascular necrosis (AVN), also called osteonecrosis, is a condition in which the bone of the femoral head (the “ball” of the hip) loses its blood supply. Without blood flow, the bone weakens and can eventually collapse, flattening the ball and causing arthritis. The earlier AVN is found, the more options there are to protect the natural hip.

At a glance

Deep groin or front-of-hip pain, often without an injury
X-rays can look normal early on; MRI finds it sooner
It often affects both hips, so the other hip is checked too
Before the ball collapses, core decompression can help preserve the hip
After collapse, hip replacement reliably relieves pain

What causes avascular necrosis?

AVN results from anything that interrupts blood flow to the femoral head. Common risk factors include:⁵

High-dose or long-term corticosteroid (steroid) use
Heavy alcohol use
Hip fractures and dislocations
Sickle cell disease and other blood disorders
Lupus and other conditions that affect blood vessels or clotting
Radiation treatment and decompression sickness (“the bends”)

In some patients, no cause is found. This is called idiopathic AVN.

Symptoms

Most people notice a gradual, deep ache in the groin or front of the hip that is worse with standing and walking. As the condition progresses, pain can occur at rest or at night, and the hip may become stiff. Some people have no symptoms in the early stages, which is one reason the other hip is checked when AVN is found.

Diagnosis and staging

Dr. Dold starts with a history, an exam and X-rays, which can often be done at the same visit. Because early AVN may not show on X-rays, an MRI is the most sensitive test. Treatment depends on the stage, and in particular on whether the ball has started to collapse:

Early (pre-collapse): the bone is affected, but the ball is still round.
Collapse: the weakened bone has begun to flatten.
Late: the joint surface is damaged and arthritis has developed.

Treatment before collapse: core decompression

When AVN is found before the ball collapses, the goal is to save the natural hip. Treatment may include protected weight bearing, addressing risk factors (for example, reviewing steroid or alcohol use with your other doctors) and, for many patients, core decompression.

Core decompression is a minimally invasive, outpatient procedure. Through a small incision on the side of the thigh and using live X-ray guidance, Dr. Dold drills one or more small channels into the affected area of the femoral head. This relieves pressure inside the bone and encourages new blood vessels to grow. The channel may also be filled with bone graft material (such as calcium phosphate, calcium sulfate or demineralized bone matrix) and/or a concentrate of your own bone marrow (BMAC).

After surgery, most patients use crutches for about 6 to 8 weeks to protect the bone while it heals, followed by a gradual return to activity. Results are better when AVN is treated early, while the affected area is small.²

Treatment after collapse: hip replacement

Once the femoral head has collapsed or arthritis has developed, core decompression is less likely to help. A total hip replacement reliably relieves pain and restores function. Dr. Dold specializes in direct anterior hip replacement, a muscle-sparing approach that is usually done as outpatient surgery with no traditional hip precautions.

Watch Dr. Dold: core decompression

Some of these videos show real surgery, so some viewers may prefer not to watch.

Core decompression of the hip for AVN

More videos on Dr. Dold’s YouTube channel.

Why early evaluation matters

AVN tends to progress. If you have deep groin pain and a risk factor such as steroid use, don’t wait for it to get worse. An MRI can find AVN while hip-preserving treatment is still an option.

What the research shows

AVN often progresses, even without symptoms. In a review of 16 studies (664 hips) where AVN was found before symptoms began, 59% went on to develop symptoms or collapse. Small lesions on the inner side of the femoral head had the lowest risk, with collapse in fewer than 10%.¹
Early treatment does better. After core decompression with multiple small drillings, 79% of patients with small, early-stage (Ficat stage I) lesions showed no progression on X-ray.²
Adding your own bone marrow cells. A 2023 analysis of 18 studies found lower rates of disease progression and of conversion to hip replacement when a concentrate of the patient’s own bone marrow cells was added to core decompression, compared with core decompression alone. Results were less favorable in older patients and after collapse.³
Hip replacement for AVN does well. Across 67 reports (3,277 hips), revision rates fell from 17% for operations before 1990 to 3% for those done in 1990 or later, similar to national joint registry results.⁴ A 2020 review concluded that hip replacement results in AVN are similar to those in osteoarthritis.⁵

What the research shows

Here is what published studies show about AVN of the hip, its risk factors and treatment.

Risk factors and early diagnosis

Corticosteroid use and alcohol are two of the most consistent risk factors, and the risk with alcohol rises with the amount consumed. MRI finds AVN before it shows on X-rays, which matters because results of hip-preserving treatment depend heavily on catching the disease before the ball collapses.

Core decompression and biologic augmentation

Several meta-analyses of randomized and comparative studies have found that adding a concentrate of the patient’s own bone marrow cells to core decompression improves pain and function and reduces progression to hip replacement compared with core decompression alone. The quality of these studies varies, so results should be viewed as encouraging rather than definitive. Other hip-preserving options, such as vascularized bone grafts and osteotomies, are performed at specialized centers and have more variable results.

Medicines and shock wave therapy

A randomized trial found that a bisphosphonate (zoledronate) did not prevent collapse. Shock wave therapy has relieved pain in early-stage AVN in some studies but has not been shown to heal the affected bone.

Hip replacement

When the femoral head has collapsed, hip replacement reliably relieves pain. Revision rates after replacement for AVN are somewhat higher than after replacement for osteoarthritis.

Why see Dr. Dold

Hip arthroscopy research in AJSM and JBJS Reviews; Stryker Advanced Hip Arthroscopy Course (2018)
Board certified by the American Board of Orthopaedic Surgery, with subspecialty certification in Sports Medicine
Fellow of the American Orthopaedic Association (FAOA), the American Academy of Orthopaedic Surgeons (FAAOS), the American College of Surgeons (FACS) and the Royal College of Surgeons of Canada (FRCSC)
Sports medicine and arthroscopy fellowship at NYU Langone / Hospital for Joint Diseases; orthopedic residency at the University of Toronto
Member of the International Society for Hip Arthroscopy (ISHA)
D Magazine Best Doctors (Collin County), 2019–2026 · Rated 4.9 on Google

Frequently asked questions

What is the first sign of avascular necrosis of the hip?

Usually a gradual, deep ache in the groin or front of the hip that is worse with standing and walking. Early AVN can also cause no symptoms at all.

Can avascular necrosis of the hip heal on its own?

Small, early areas sometimes stabilize, but AVN often progresses. Early treatment gives you more options to save the natural hip.

What is core decompression surgery?

An outpatient procedure that drills small channels into the affected bone to relieve pressure and encourage new blood flow. It is used before the ball of the hip collapses.

How long is recovery after core decompression?

Most patients use crutches for about 6 to 8 weeks to protect the bone, then gradually return to normal activity.

Will I need a hip replacement for AVN?

Not always. If the ball of the hip has not collapsed, core decompression may preserve it. If it has collapsed or arthritis has developed, hip replacement is usually the most reliable treatment.

Ready to get your hip checked? Request an appointment online or call 469-850-0680. Our staff will contact you by phone and text within an hour of your request (during business hours, Monday–Friday, 8 am–5 pm). Walk-in visits are welcome Monday, Wednesday and Friday, 8:30–10:30 am. Same-day appointments available. Dr. Dold accepts most major insurance plans, including Medicare and Tricare. Please call 469-850-0680 to confirm your coverage.