Avascular Necrosis (AVN) of the Hip: Symptoms, Causes & Treatment Options

If you've just been told you have avascular necrosis — often shortened to AVN, and also called osteonecrosis — you're probably feeling two things at once: you'd never heard of it before, and the MRI looked alarming. That reaction is completely normal. The most important thing to understand up front is that AVN is different from arthritis, and that treatment depends heavily on the stage — a hip replacement is only one part of a broader spectrum, not a foregone conclusion.

What AVN is (and how it differs from arthritis)

Bone is living tissue, and it needs a steady blood supply to stay healthy. In avascular necrosis, the blood supply to the head of the femur — the “ball” of the ball-and-socket hip joint — becomes disrupted. Without adequate circulation, the bone cells in that area begin to die, and the bone gradually weakens. Over time, if the process continues, the weakened bone can collapse, changing the once-round shape of the ball.

This is fundamentally different from hip osteoarthritis, which is a gradual wearing of the cartilage that caps the joint. AVN starts in the bone beneath the cartilage. The two are connected, though: once the femoral head collapses and loses its smooth shape, the joint surface is damaged and secondary arthritis tends to follow. Understanding that sequence — bone first, surface later — is the key to why timing matters so much.

Causes and risk factors

AVN usually reflects a combination of factors rather than a single cause. The most recognized risk factors include:

• Corticosteroid (steroid) use — particularly high-dose or prolonged use, one of the most common associations.
• Heavy alcohol use — another well-established risk factor.
• Trauma — a hip fracture or dislocation can directly disrupt the blood supply to the femoral head.
• Certain medical conditions — including blood and clotting disorders, sickle cell disease, and some autoimmune or inflammatory conditions, among others.
• Idiopathic AVN — in a meaningful number of cases, no clear cause is ever identified. This is common, and it doesn't change how we approach treatment.

Symptoms

Early AVN can be silent, which is part of why MRI findings sometimes come as a surprise. As it progresses, the symptoms tend to look like this:

• Groin pain — the most common location, reflecting the hip joint itself.
• Hip pain with walking or weight-bearing — pain that worsens when you load the joint.
• Loss of range of motion — the hip feels stiffer and moves less freely.
• A developing limp — often as you unconsciously protect the hip.
• Progressive symptoms — unlike a passing strain, AVN pain tends to build over time, especially once collapse begins.

These overlap with other hip problems, including nighttime hip pain and arthritis — another reason that pinning down the diagnosis with the right imaging matters.

How AVN is diagnosed

Diagnosis combines your history and risk factors with imaging — and the choice of imaging is important:

• X-rays — useful, and the usual first step. But early AVN often doesn't show up on X-rays, because the bone hasn't yet changed shape. X-rays are better at showing later changes like flattening, collapse, or arthritis.
• MRI — the most sensitive test for AVN. It can detect the loss of blood supply at an early stage, well before any collapse and often before an X-ray looks abnormal at all. This is exactly why so many patients are told their X-ray was “normal” but the MRI found something.

Imaging is also used to stage the AVN — essentially, how far along it is, and critically whether the femoral head has collapsed yet. That staging is one of the single most important factors guiding treatment.

Treatment depends on the stage

There isn't one treatment for AVN — there's a spectrum, and the right choice depends heavily on the stage, your symptoms, your age, and the specifics of your hip. The most important message: not everyone with AVN immediately needs a hip replacement.

Earlier-stage AVN (before collapse)

When AVN is caught early, before the femoral head has collapsed, the goal is to relieve symptoms and, when possible, try to protect the hip:

• Observation and monitoring — appropriate in selected cases, with imaging to watch how things progress.
• Activity modification — adjusting loading and high-impact activity to reduce stress on the hip.
• Protected weight-bearing — limiting weight through the hip when appropriate.
• Hip-preserving procedures — in suitable patients, a procedure such as core decompression (creating channels in the bone to relieve pressure and stimulate blood supply) may be considered to try to delay or prevent collapse. Whether a preservation procedure is appropriate is highly individual.

Earlier stages don't always behave predictably, and outcomes vary — but the point is that options exist beyond replacement, and they're most relevant before collapse.

Advanced AVN (after collapse)

Once the femoral head has collapsed and lost its round shape, the joint surface is damaged and secondary arthritis commonly develops. At that point, hip-preserving procedures are generally less effective, and a hip replacement becomes a reasonable option — particularly when the hip is significantly painful and limiting your life despite other measures.

The good news, if you reach that stage, is that hip replacement is one of the most successful operations in medicine. You can read about the muscle-sparing direct anterior hip replacement Dr. Harb specializes in, how long a modern hip replacement lasts (more than 90% intact at 30 years), and the signs it may be time to consider one.

Whatever the stage, symptom-focused, nonsurgical measures still matter — our guide to nonsurgical treatment of hip & knee arthritis covers the supportive options that help keep you comfortable and active while you and your surgeon decide on the right plan.

What patients commonly tell me

People recognize themselves in their own words, and AVN comes with a very recognizable set of reactions. These are the kinds of things I hear most:

If those sound like you, you're in good company — and the next step is the same for everyone: understand the stage, and build a plan that fits it.

The bottom line: AVN of the hip is serious and worth addressing promptly, but it is not a single, fixed path to surgery. Early diagnosis opens doors, the stage drives the decision, and a hip replacement — when it's needed at all — is one excellent option at the far end of a much broader spectrum.