Hip osteonecrosis, also called avascular necrosis or AVN, occurs when the blood supply is interrupted to the head of the femur (the ball of the ball and socket joint). When the blood supply is cut, the bone receives fewer nutrients and oxygen leading to bone death. What causes hip osteonecrosis, and what can we do about it?

picture of avascular necrosis of hip

Cause of hip osteonecrosis

Most causes of hip avascular necrosis or AVN are unknown. However, cortisone use, alcohol intake, trauma such as a fracture, inflammatory arthritis such as lupus, sickle cell disease, Crohn’s disease, and vasculitis are all associated risk factors.

Generally, men between the ages of 40-60 are most a risk.

Osteonecrosis hip symptoms

avascular necrosis of hip

When the blood flow is interrupted, the bone dies, leading to collapse. Subsequently, the articular cartilage collapses, producing debilitating arthritis.

Generally, people with avascular necrosis describe the new onset of pain in the hip or groin. As the disease progresses, walking can become difficult. Night pain is also common. Your doctor will examine your hip and groin. Hip movements are often painful, especially when your doctor rotates your hip.

You must consider other causes of hip and groin pain, such as hip impingement, arthritis, dysplasia, or bone marrow oedema.

Often, we confirm a diagnosis by using imaging.

First, we start with a hip X-ray. In early cases, we can see sclerosis of the dead area of bone, also called sclerosis. In advanced cases, we see the collapse of the ball of the hip and arthritis. Sometimes, an X-ray is normal, necessitating an MRI.

MRI scan reveals swelling or bone oedema of the femoral head. As the disease progresses, there is the destruction of the articular cartilage, leading to the collapse of the head and early osteoarthritis.

Osteonecrosis hip treatment

Treatment of Osteonecrosis of the hip is complex.

If symptoms are detected early, rest with crutches, and anti-inflammatory medication can help restore blood flow. Sometimes, we use a special drug called bisphosphonates, such as alendronate. Some studies show benefits in improving blood flow and preventing bone collapse, but others show no effect.

Surgical options in the early stages before damage to the cartilage occurs include hip decompression and surgical bone grafting. Surgical decompression involves drilling one or larger holes in the head of the femur to increase blood flow. Sometimes, we combine decompression with bone grafting from another healthy site to improve blood flow.

A total hip replacement is a good option if the osteonecrosis is too advanced and has led to collapse. This procedure gives good pain relief and is a good option for people above the age of 40 with evidence of collapse.

Final word from Sportdoctorlondon about hip osteonecrosis

AVN, or avascular necrosis of the hip, is a rare cause of sudden pain and limited movement in the hip or groin. Early diagnosis with imaging is essential to improve outcomes. You should see a specialised sports doctor who can get you diagnosed and treated early.

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