Avascular Necrosis of the Femoral Head

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Avascular Necrosis of the Femoral Head

Hip osteonecrosis can weaken the ball of the hip joint. Early diagnosis matters because treatment options change if the bone begins to collapse.




John Miller Physiotherapist


Shane Armfield Physiotherapist

Article by
John Miller,
Shane Armfield



Stages of avascular necrosis affecting the femoral head of the hip
Avascular necrosis may progress from early bone changes to flattening or collapse of the femoral head.

What is avascular necrosis of the femoral head?

Avascular necrosis, also called osteonecrosis, affects the rounded top of the thigh bone that forms the ball of the hip joint. Reduced blood flow damages the bone tissue beneath the joint surface.

The bone may initially retain its normal shape. However, continued damage can weaken the supporting structure. The femoral head may then flatten or collapse, which can damage the joint surface and lead to secondary hip arthritis.

Early symptoms can resemble other causes of hip pain or hip and groin pain. Therefore, symptoms alone cannot confirm the condition.

Avascular necrosis at a glance

Usual pain area

Deep groin or front-of-hip pain, sometimes extending into the buttock or thigh.

Early imaging

An X-ray may appear normal during the early stages. MRI is more sensitive to early bone changes.

Treatment direction

Management depends on the stage, size and location of the affected area and whether collapse has occurred.





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What causes avascular necrosis of the hip?

Avascular necrosis may develop after an injury interrupts blood flow to the femoral head. It can also occur without a major injury.

Traumatic causes

A hip fracture or dislocation can damage the blood vessels that supply the femoral head. The risk depends on the injury and the extent of blood-vessel disruption.

Non-traumatic causes

Recognised associations include prolonged or high-dose corticosteroid use, high alcohol intake, some blood disorders and several medical treatments or conditions.

Some people have more than one risk factor. In other cases, clinicians cannot identify a definite cause. Your doctor may review previous injuries, prescribed medicines, alcohol exposure and relevant medical history.

What are the symptoms of hip osteonecrosis?

Early avascular necrosis may not cause symptoms. As the condition progresses, weight-bearing and hip movement commonly become more uncomfortable.

  • Deep groin or front-of-hip pain
  • Aching in the buttock or upper thigh
  • Pain while walking, standing or climbing stairs
  • Hip stiffness or reduced movement
  • A limp or reduced weight-bearing tolerance
  • Difficulty with work, exercise or everyday activities

Groin pain with bending, twisting or prolonged sitting can also occur with conditions such as femoroacetabular impingement syndrome or a hip labral tear. Assessment and imaging help distinguish these conditions.

When should you seek urgent help?

Seek urgent medical care following a major hip injury, particularly if you cannot stand or place weight through the leg. You should also seek timely medical assessment for severe unexplained pain, rapidly worsening function, fever, significant illness or pain that remains intense at rest.

For broader guidance, see when hip pain may require urgent assessment.

How is avascular necrosis diagnosed?

Diagnosis usually combines your history, a clinical examination and medical imaging. Your clinician will consider the pain pattern, hip movement, walking tolerance and any relevant risk factors.

  1. Clinical assessment

    The assessment may include hip movement, strength, walking and tests that reproduce joint-related symptoms. These findings help guide imaging but do not confirm osteonecrosis by themselves.

  2. X-ray

    X-rays can show flattening, collapse or arthritic change in later stages. However, an early X-ray may appear normal.

  3. MRI

    MRI can detect early changes before they become visible on an X-ray. It also helps define the location and extent of the affected bone.

  4. Staging and specialist review

    Your doctor or orthopaedic surgeon may use the imaging findings to stage the condition and decide whether joint-preserving treatment remains suitable.

Why does the stage of avascular necrosis matter?

The main treatment decision is whether the femoral head has retained its shape or has begun to collapse.

Before collapse

Joint-preserving procedures may remain possible. The decision depends on the size and location of the lesion, symptoms, age, health and activity goals.

After collapse

Once the femoral head has lost its shape, joint-preserving options become less predictable. Advanced joint damage may lead to consideration of total hip replacement.

How is avascular necrosis treated?

Treatment depends on the disease stage, symptoms, the amount of bone involved and your general health. A doctor or orthopaedic surgeon should guide treatment of the underlying bone disorder.

Load and activity management

Your treating team may recommend reducing painful loading or using a walking aid for a period. This can make walking more comfortable, although reducing weight-bearing alone does not reliably reverse the damaged bone.

Core decompression

Core decompression is a joint-preserving operation used in selected earlier-stage cases. The surgeon creates one or more channels in the affected area to reduce pressure and encourage a healing response. Some procedures also use bone grafts or biological material.

Other joint-preserving procedures

Selected patients may be considered for bone grafting, osteotomy or another procedure intended to support the femoral head. Suitability varies and requires specialist assessment.

Total hip replacement

Total hip replacement may be recommended when collapse or advanced joint damage causes persistent pain and substantial loss of function.

How can physiotherapy help?

Physiotherapy does not restore the lost blood supply or reverse dead bone tissue. Instead, it supports safe movement and function before or after medical treatment.

  • Adjusting activities and loads that aggravate the hip
  • Improving the use of crutches or another walking aid
  • Maintaining comfortable hip and lower-limb movement
  • Building strength without excessive joint irritation
  • Improving balance and walking confidence
  • Preparing for surgery when appropriate
  • Supporting rehabilitation after a joint-preserving procedure or hip replacement

The exercise plan should match the disease stage and medical advice. High-impact exercise, deep loaded hip positions or painful strength work may not suit every person.

What should you do next?

  1. Do not ignore persistent groin pain

    Arrange an assessment if pain persists, affects walking or occurs alongside recognised risk factors.

  2. Discuss suitable imaging

    Ask your doctor whether MRI is appropriate when symptoms raise concern despite a normal or uncertain X-ray.

  3. Reduce repeated flare-ups

    Temporarily reduce painful impact, prolonged walking and other activities that noticeably worsen symptoms.

  4. Coordinate your care

    Use physiotherapy alongside GP and orthopaedic advice rather than as a substitute for medical investigation or specialist treatment.

Hip pain

Explore common causes of pain around the hip, groin and buttock.

Hip arthritis

Learn how hip joint degeneration may affect movement, walking and everyday function.





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References

  1. Hines JT, Jo WL, Cui Q, et al. Osteonecrosis of the femoral head: an updated review of ARCO on pathogenesis, staging and treatment. J Korean Med Sci. 2021;36:e177.
  2. Ko YS, Kim HJ. Updating osteonecrosis of the femoral head. Hip Pelvis. 2023;35(3):147–158.
  3. Qi T, et al. Hip joint-preserving strategies for treating osteonecrosis of the femoral head. 2025.
  4. Yue J, et al. Reliability and repeatability of the 2021 ARCO classification for early-stage osteonecrosis of the femoral head. BMC Musculoskelet Disord. 2023.
  5. Konarski W, et al. Effectiveness of different types of core decompression in osteonecrosis of the femoral head. 2025.

Avascular necrosis FAQs

What is avascular necrosis of the femoral head?

Avascular necrosis of the femoral head is damage to the ball of the hip joint caused by inadequate blood flow. The bone can weaken and may eventually flatten or collapse.

What are the early symptoms of hip osteonecrosis?

Early disease may cause no symptoms. When symptoms develop, they often include deep groin or hip pain that worsens during walking, standing or stairs.

Can an X-ray miss avascular necrosis?

Yes. An X-ray may appear normal during the early stages. MRI can detect bone changes before collapse becomes visible on an X-ray.

Can avascular necrosis heal without surgery?

The outlook varies with the cause, stage and size of the affected area. Some early cases may be managed without immediate surgery, but close medical monitoring remains important because the condition can progress.

Does physiotherapy treat avascular necrosis?

Physiotherapy cannot restore dead bone tissue. It can assist with load management, walking, strength, mobility and rehabilitation before or after medical or surgical treatment.

When is core decompression considered?

Core decompression is generally considered for selected earlier-stage cases before major collapse. An orthopaedic surgeon determines suitability from imaging, symptoms and individual factors.

When might hip replacement be needed?

Hip replacement may be considered when the femoral head has collapsed or advanced joint damage causes persistent pain and substantial loss of function.



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