Hip Avascular Necrosis (AVN): Treatment Options

Hip Avascular Necrosis (AVN): Treatment Options

Avascular necrosis, A V N for short, is a condition where there is a lack of blood supply to the ball of the thigh bone, known as the femoral head. Without nutrients that the blood supply provides, the bone cells in this area start to die off, resulting in changes of the bone structure and the cartilage that lines the hip joint, which leads to pain and stiffness.

Avascular necrosis is a progressive disease that worsens over time, ranging from a few months to years. This progression is staged using imaging tests and patient symptoms to help guide treatment. One common classification system for AVN identifies 5 different stages.

Stage 0 means that the hip joint looks normal on x-rays and the patient likely has no symptoms. Stage 1 means some changes can be seen on x-ray and a patient may start to develop hip pain. MRI studies may also show swelling within the bone.

Stage 2 demonstrates bone cyst formation while the femoral head maintains its round shape. In stage 3, patients have continued hip pain and now stiffness of the joint. Imaging will demonstrate flattening of the femoral head.

Stage 4 includes progression of pain now impacting a patient's ability to walk, with imaging demonstrating collapse of the femoral head and severe arthritis of the hip joint.

Nonsurgical treatment for AVN can help relieve pain in early stages. These treatments include the use of assistive devices, such as crutches during activity to avoid putting body weight through the affected hip. Other options include physical therapy, and use of anti-inflammatory medications or acetaminophen.

Though these measures can help limit pain, they will not treat the underlying cause or stop progressio. As pain becomes unresponsive to nonsurgical treatment, there are several different surgical options to treat avascular necrosis of the hip.

These can be divided into 2 groups, femoral head sparing, meaning that the patient maintains the normal anatomy of their thigh bone without having to remove the ball of the hip joint. The second option is arthroplasty, known as total joint replacement.

Based on the widely used classification system, femoral head sparing procedures are best for younger patients who do not demonstrate signs of bone collapse on imaging or stages 0 through 2. Once the shape of the femoral head is altered, a total hip replacement is recommended.

There are a few femoral head sparing procedures that have been used in the treatment of avascular necrosis of the hip. Core decompression is a minimally invasive procedure aimed to remove dead bone within the femoral head using a drill that can expand in size. This helps to relieve pressure in the bone and promote formation of new blood vessels.

After the dead bone is removed, surgeons may choose to fill the void with a mixture of biologic fluids, P R P for example, combined with new bone. Another option is to place a graft of bone where the old bone once was.

Another femoral head sparing procedure that has been used is called a rotational osteotomy. Osteotomy means cutting of the bone. In this procedure, cuts are made in the upper thigh bone that allow the surgeon to rotate the ball, the femoral head.

The goal is that by rotating the ball of the hip joint, the area where bone cells are dying is moved and will no longer receive force, with weight bearing activities like walking, in turn, providing pain relief.

Once avascular necrosis progresses to a later stage where the shape of the femoral head has changed, total hip replacement is usually recommended. In fact, 10% of total hip replacements that are performed in the United States each year are attributed to avascular necrosis.

In a hip replacement, the ball of the hip joint is removed completely. The socket is resurfaced with a metal cup, a metal stem is placed in the upper thigh bone, and a ball is attached, made of either metal or ceramic. A plastic or ceramic liner is then used in between the ball and cup, acting as the new cartilage surface, allowing for smooth movement of the hip joint once again.

After surgery for AVN, recovery will vary slightly depending on what procedure was performed. Overall, there may be a period where the amount of weight they place on the affected leg is restricted. With guidance from the surgeon and a physical therapist, that restriction will be lifted.

Range of motion exercises are added and usually within 6-12 weeks, many patients are back to their daily activities.