Understanding Hip Osteonecrosis Or Avascular Necrosis

Medically Reviewed By:

Dr. Chaz Fausel, MD

Dr. Chaz Fausel is a Denver-based interventional orthopedics specialist and Regenexx educator, trained at Emory and the Centeno-Schultz Clinic.

Hip osteonecrosis, also known as avascular necrosis (AVN), is a condition that can cause significant pain and reduced mobility. This progressive condition can impact daily activities, making it essential for those affected to understand its risk factors, progression, and treatment options. 

Understanding hip osteonecrosis empowers individuals to make informed choices about managing symptoms and seeking appropriate medical support.

What Is Osteonecrosis?

Osteonecrosis occurs when the bone in the hip deteriorates due to a disrupted blood supply, which can eventually lead to joint collapse and the need for a hip replacement.

Historically, osteonecrosis was thought to result mainly from a lack of blood supply to the hip bone, which is why it is also known as avascular necrosis. While a reduced blood supply can occur, particularly due to surgical damage to blood vessels, hip osteonecrosis often develops because of damage to progenitor cells—cells within the bone responsible for producing new bone. 

Factors that can impair these cells include certain steroid medications, chronic alcohol use, or exposure to specific chemicals. When osteonecrosis is identified early, native joint preservation may be possible. One traditional approach is a surgical procedure known as core decompression, which involves creating a channel through the healthy bone into the affected area. 

This technique aims to relieve pressure and allow healthy bone marrow, containing progenitor cells, to reach the damaged bone and support the body’s natural healing process.

Exploring The Causes Of AVN Of The Hip

AVN of the hip can result from various underlying factors that disrupt blood flow to the bone tissue, ultimately leading to its gradual deterioration. While some cases are linked to specific medical conditions or injuries, others may be associated with lifestyle factors or certain medications. The following are common contributors to the development of hip osteonecrosis:

Traumatic AVN

Traumatic AVN occurs when an injury directly disrupts the blood vessels that supply the femoral head, depriving the bone tissue of essential nutrients and oxygen. This lack of blood flow leads to the deterioration of bone cells, gradually leading to the breakdown of the hip joint. Trauma-related AVN often progresses more rapidly than non-traumatic forms, making timely intervention essential.

• Hip fracture: One of the most common traumatic causes of AVN, hip fractures can impair blood flow to the femoral head, heightening the risk of AVN as the bone struggles to heal without sufficient blood supply.

Non-traumatic AVN

Non-traumatic AVN develops without a direct injury to the hip, instead arising from factors that limit blood flow to the bone. This type of AVN is often linked to lifestyle habits, certain medications, or specific medical conditions that interfere with circulation or bone health. 

Non-traumatic AVN generally progresses gradually, and understanding the contributing factors is essential for identifying and managing risks. Common non-traumatic causes of AVN in the hip include:

• Steroid use: Prolonged or high-dose corticosteroid use can weaken blood vessels and reduce blood flow to the bones, increasing the risk of AVN.
• Excessive alcohol consumption: Heavy alcohol use may impair blood circulation to the bones, causing cellular damage and raising the risk of AVN.
• Medical conditions: Disorders like lupus, sickle cell disease, and Gaucher’s disease can disrupt blood flow or bone health, raising the risk of AVN.
• Sickle Cell: Sickle cell disease causes red blood cells to become misshapen, which can block small blood vessels. This blockage may restrict blood flow to the bone tissue and lead to osteonecrosis.
• Radiation therapy: Radiation treatments for cancers near the hip can damage local blood vessels, sometimes leading to AVN.
• Bisphosphonate use: Because of their effects on bone remodeling, long-term or high-dose use of bisphosphonates has been associated with AVN in some patients.
• Decompressionsickness: Commonly referred to as “the bends,” decompression sickness may cause air bubbles to form in the blood, obstructing blood circulation to bones and potentially leading to AVN.

Signs And Symptoms Of Joint Damage From AVN

As joint damage from AVN progresses, affected individuals may experience symptoms that interfere with their daily activities and comfort. These symptoms often begin subtly and intensify over time, indicating the need for evaluation and appropriate care. Key symptoms of joint damage include:

• Intermittent Pain: In the early stages of AVN, hip pain may be occasional and triggered by weight-bearing activities.
• Persistent Pain: Over time, pain becomes more persistent, often accompanied by stiffness, restricting comfortable movement.
• Limited Range of Motion: As the joint continues deteriorating, the hip’s flexibility decreases, limiting routine movements and daily tasks.
• Difficulty Walking or Running: Walking, running, or climbing stairs may become increasingly challenging as pain and stiffness worsen, impacting overall mobility.

How Is AVN Diagnosed?

To diagnose AVN of the hip, healthcare providers use a combination of physical exams, imaging tests, and a review of the patient’s medical history. The diagnostic process usually begins with assessing symptoms along with questions about any history of injury, medication use, or lifestyle factors that could contribute to AVN.

Imaging tests are critical for confirming AVN and evaluating the extent of joint damage. Commonly used imaging methods include:

• X-rays: X-rays are primarily used to detect advanced AVN, showing bone collapse or structural changes in the joint.
• MRI scans: MRI provides detailed images of bone and soft tissue, enabling early detection of AVN before substantial bone damage occurs.
• CT scans: CT scans offer a cross-sectional view of the hip, assisting in evaluating bone structure and any signs of deterioration. However, these scans are typically used to track more advanced AVN with collapse, similar to X-rays.
• Bone scans: Occasionally used to detect AVN, bone scans show blood flow patterns in the hip joint, helping identify areas at risk of necrosis.

By combining these tests, healthcare providers can accurately diagnose AVN and develop an appropriate plan to manage joint health.

Common Treatment Options For Hip Osteonecrosis

Treatment for hip osteonecrosis aims to manage symptoms, preserve joint function, and slow disease progression. Depending on the stage of AVN and individual needs, several treatment options are available:

• Weight-Bearing Management: Reducing weight on the hip, often with the assistance of crutches or walkers, can relieve stress on the joints and slow further damage.
• Physical Therapy: Exercises designed to enhance mobility and strengthen surrounding muscles can improve joint support and function.
• Hyperbaric Oxygen (HBO) Therapy: Increased oxygen levels through HBO therapy may stimulate bone healing and improve blood supply to the hip.

NSAIDs have also been implicated in interference with bone healing (3).

• Total Hip Replacement: In advanced cases, replacing the damaged hip with an artificial joint can restore function and alleviate pain.
• BoneGrafting: Transplanting bone tissue from another area helps support hip structure and encourages healthy bone growth, aiding recovery.
• Hip PAO Surgery: Periacetabular osteotomy (PAO) is a surgical procedure used to address hip dysplasia by repositioning the hip socket to support joint stability. It is often considered for younger patients to help preserve the hip joint. Read More About Periacetabular Osteotomy.

How Bone Marrow Aspirate Concentrate (BMAC) Is Used In Managing Osteonecrosis

Research since the 1990s has investigated the potential role of BMAC in hip osteonecrosis management. Studies suggest that BMAC may help support joint health and delay the need for hip replacement. French orthopedic surgeon Philippe Hernigou published results in 2002 on the use of BMAC in combination with core decompression to manage osteonecrosis(1).

A study by Hernigou examined the use of BMAC with core decompression in early-stage osteonecrosis (ARCO stages 1 and 2). It reported that 94% of patients in the study did not require hip replacement within 5 to 10 years.

A 2009 follow-up study on 534 cases, with an average of 12 years of follow-up, observed favorable patient-reported outcomes over time (2). This procedure has been utilized for several decades, with research documenting its applications and patient experiences.

BMC Procedure For Treating Osteonecrosis Of The Hip

At a location in the licensed Regenexx network, procedures using BMC have evolved from surgical core decompression to a percutaneous approach. This refinement has made the procedure less invasive compared to traditional surgical core decompression, potentially reducing recovery time.

Some patients report being able to bear weight within days, though recovery times can vary.

The image above shows an example of a patient with early-stage osteonecrosis, who experienced significant healing following treatment with the percutaneous BMC injection technique. This image was originally posted in 2014.

Explore Different Approaches To Managing Hip Joint Problems

Procedures using Regenexx injectates may support joint health and help reduce the need for hip replacement in some patients. BMC injections use the patient’s own healing agents to support bone health in the affected joint, offering an alternative for patients considering options other than surgery. 

Since 2014, physicians in the licensed Regenexx network have used a percutaneous (needle-based) approach, offering an alternative to surgical core decompression for some patients.

Some studies from institutions like Yale University have examined the potential role of BMC in osteonecrosis care (4). This growing adoption by medical centers highlights the role of BMC in advancing osteonecrosis treatment. As regenerative techniques like BMC evolve, the outlook for managing hip joint conditions continues to expand, offering patients potential options to support mobility and overall well-being.

References:

1. Hernigou P, Beaujean F. Treatment of osteonecrosis with autologous bone marrow grafting. Clin Orthop Relat Res. 2002 Dec;(405):14-23. doi: 10.1097/00003086-200212000-00003. PMID: 12461352.
2. Hernigou P, Poignard A, Zilber S, Rouard H. Cell therapy of hip osteonecrosis with autologous bone marrow grafting. Indian J Orthop. 2009 Jan;43(1):40-5. doi: 10.4103/0019-5413.45322. PMID: 19753178; PMCID: PMC2739495.
3. Giannoudis, P. V., et al. “Effect of Non-Steroidal Anti-Inflammatory Drugs on Bone Healing: A Critical Analysis.” Dove Press Journal of Drug Design, Development and Therapy, vol. 3, no. 5, 2011, pp. 1668–1682.
4. Yale School of Medicine. Stem Cell Therapy Reduces Need for Nearly 10% of Hip Replacements. https://medicine.yale.edu/news-article/stem-cell-therapy-reduces-need-for-nearly-10-of-hip-replacements/

Medically Reviewed By:

Dr. Chaz Fausel, MD

Dr. Chaz Fausel is a Denver-based interventional orthopedics specialist and Regenexx educator, trained at Emory and the Centeno-Schultz Clinic.