Osteonecrosis of the Knee Treatment
Osteonecrosis of the knee — also called avascular necrosis or AVN — is a condition in which the blood supply to a section of bone within the knee joint is disrupted, causing the affected bone to weaken, die, and eventually collapse. The medial femoral condyle — the weight-bearing surface on the inner side of the thighbone — is the most commonly affected area, though osteonecrosis can also involve the lateral femoral condyle or the top of the tibia. As the bone deteriorates, the smooth cartilage surface above it loses its structural support and begins to flatten and fragment, leading to progressive deterioration of the knee joint and the development of secondary osteoarthritis. The condition is most common in women over 60 but can affect patients of any age, and because the bone damage is often irreversible once it progresses past the early stages, prompt diagnosis and treatment are critical for preserving the joint.
Dr. Jonathan Glashow is a board-certified orthopedic surgeon and Clinical Associate Professor of Orthopedic Surgery at NYU Grossman School of Medicine, with over 30 years of experience managing complex knee conditions — including the joint-preservation and surgical decision-making that osteonecrosis demands. Osteonecrosis requires a treatment approach that matches the stage of the disease: early-stage lesions may respond to unloading and biologic therapies, while advanced disease with bone collapse may require osteotomy to redirect weight-bearing forces or partial or total knee replacement to restore joint function. Dr. Glashow’s practice offers the full range of these options — from bone marrow concentrate and core decompression to robotic-assisted knee replacement — allowing him to tailor treatment precisely to each patient’s disease stage and functional goals. As Chief Medical Officer for the New Jersey Devils and Philadelphia 76ers and a Castle Connolly Top Doctor every year since 2000, he provides osteonecrosis evaluation and treatment with same-day imaging at his Upper East Side practice in New York City.
Causes and Symptoms of Knee Osteonecrosis
The cause of knee osteonecrosis is not always known. Some risk factors that can restrict blood supply to the bones in the knee joint can include long-term steroid use, obesity, knee injuries, organ transplants, excessive alcohol use and certain medical conditions. The progression of the disease can occur over several months. Symptoms can include:
- Swelling of the front and inside of the knee
- Tenderness to touch
- Pain when putting weight on the knee
- Pain when bending
- Limited range of motion
Osteonecrosis of the knee is more common in women, especially those over 60. Without treatment, the end of the femur or tibia, with the attached cartilage, can collapse. Osteonecrosis can lead to severe osteoarthritis and joint dysfunction, causing pain and limiting mobility.
Early detection can prevent bone and cartilage deterioration with treatment. If osteonecrosis has progressed past the stage of conservative treatment, surgery may be necessary to restore blood flow and stability to the bone and knee joint.
Jonathan Glashow, MD, Orthopedic Surgery & Sports Medicine offers advanced treatment options for complex knee conditions, like osteonecrosis. If you have been diagnosed with osteonecrosis or are experiencing symptoms, contact our clinic on NYC’s Upper East Side to discuss treatment. Our top orthopedic specialists can determine the best treatment plan to improve your knee disorder.
Frequently Asked Questions About Osteonecrosis of the Knee
What causes osteonecrosis of the knee?
Osteonecrosis occurs when the blood supply to a section of bone in the knee is disrupted, causing the bone cells in that area to die. The condition is classified as either spontaneous (also called primary or idiopathic) — where no clear cause is identified and it most commonly affects women over 60 — or secondary, where a known risk factor is present. Common risk factors for secondary osteonecrosis include long-term corticosteroid use, excessive alcohol consumption, sickle cell disease, lupus and other autoimmune conditions, prior knee injury or surgery, organ transplantation, obesity, and certain blood-clotting disorders. In many cases, the specific trigger is never definitively identified.
How is osteonecrosis of the knee different from osteoarthritis?
While both conditions can produce knee pain, swelling, and loss of function, they have different underlying causes. Osteoarthritis is a gradual wearing down of the cartilage surface from long-term use and load. Osteonecrosis is a loss of blood supply to the bone beneath the cartilage, causing the bone itself to weaken and collapse — which then secondarily damages the cartilage above it. The distinction matters because the treatment approach differs: osteonecrosis requires addressing the bone health problem, not just the cartilage. MRI is the key diagnostic tool for distinguishing between the two conditions, as it can reveal the characteristic bone marrow changes of osteonecrosis that X-rays may miss in the early stages.
How is osteonecrosis of the knee diagnosed?
Dr. Glashow begins with a clinical examination that assesses pain location, swelling, range of motion, and weight-bearing tolerance. X-rays may appear normal in the early stages of osteonecrosis, which is why an MRI is essential — it can detect bone marrow edema and early vascular changes before any structural collapse has occurred. In some cases, a bone scan may also be used. Early diagnosis is critical because treatment options are most effective before the bone collapses and the joint surface is permanently compromised. Same-day imaging is available at Dr. Glashow’s Upper East Side practice.
What are the stages of osteonecrosis?
Osteonecrosis of the knee is typically classified into four stages. Stage 1 involves bone marrow changes visible on MRI but no structural damage — symptoms may be mild or absent. Stage 2 shows early bone changes on X-ray with intact joint surface. Stage 3 involves a subchondral fracture — a crack in the bone just beneath the cartilage — which may produce a flattening of the joint surface. Stage 4 involves collapse of the bone and significant destruction of the joint surface, leading to secondary osteoarthritis. Treatment decisions are guided primarily by the stage at the time of diagnosis.
What treatment options are available for osteonecrosis of the knee?
Treatment depends on the stage of the disease and the extent of bone involvement. Early-stage osteonecrosis may respond to protected weight-bearing with crutches, anti-inflammatory medications, and biologic therapies such as bone marrow concentrate to support bone healing. Core decompression — a surgical procedure in which small channels are drilled into the affected bone to reduce pressure and stimulate new blood vessel growth — can be effective for early- to mid-stage lesions. For patients with more advanced disease involving bone collapse on one side of the knee, a high tibial osteotomy may be used to redirect weight-bearing forces away from the damaged area. When the joint surface has collapsed significantly, partial or total knee replacement may be the most reliable option for restoring function. Dr. Glashow evaluates each patient’s MRI and clinical findings to determine the most appropriate treatment for their specific stage.
Can osteonecrosis of the knee be cured?
Early-stage osteonecrosis — particularly small lesions detected before any bone collapse has occurred — can sometimes heal or stabilize with appropriate treatment, including unloading, biologic therapy, and core decompression. However, once significant bone collapse and joint surface destruction have occurred, the damage is generally irreversible and treatment shifts toward managing symptoms and restoring function through surgical reconstruction or replacement. This is why early detection through MRI is so important — the earlier the condition is identified, the more options are available to preserve the joint.
