Osteonecrosis of the Hip

Osteonecrosis is a condition that is characterised by death of bone cells due to lack of blood supply. This condition commonly affects the hip and usually both hips are involved.

The hip consists of the head of the thigh bone (femur) which fits into the cup-like structure (acetabulum) of the pelvis in the form of a ball-and-socket joint. Between these bones is the articular cartilage which is a slippery tissue that allows the bones to move smoothly over each other.

Disruption of blood flow to the femoral head results in inadequate nourishment which gradually causes breakdown and collapse of the bone. The condition can be very painful and disabling. Osteonecrosis is commonly seen in men between 40 and 65 years of age.

The risk factors for osteonecrosis of the hip include:

• Hip injuries such as fractures, dislocations, or injuries which can damage blood vessels
• Alcoholism which may result in fatty deposits in the blood vessels
• Long-term use of steroid medications
• Certain medical conditions such as sickle cell disease, Crohn’s disease and other diseases involving the bone and blood vessels.

In the early stages of osteonecrosis of the hip, there may be mild pain which gradually increases with weight bearing and later even at rest. Once the bone collapses the pain will increase dramatically and there will also be limitation in range of motion. The time taken between initial symptoms and final stage of the disease may be several months to a year.

Your doctor will discuss your symptoms and prior medical history. This will be followed by physical examination of the hip testing strength and range of motion to determine which specific motions exacerbate your symptoms. Imaging studies such as X-rays to look for bone abnormality and MRIs which provide greater detail and can identify early stages of osteonecrosis may be ordered.

Conservative treatment such as pain medications and use of crutches may relieve pain to a certain extent and slow disease progression. However, surgical treatment is usually required to treat osteonecrosis of the hip. Various surgical options include:

• Core Decompression: The procedure involves drilling several small holes or a large one into the head of the femur to relieve pressure and stimulate blood supply to the area. This procedure is generally performed in the early stages of osteonecrosis and is usually successful in preventing bone collapse.
• Osteotomy: The procedure involves reshaping of the bone to reduce the amount of stress on the affected area. Recovery from this procedure may require several months with limited mobility. This procedure is used during the early stages of osteonecrosis.
• Bone Graft: The procedure involves transplanting healthy bone along with its blood supply to the affected area. There is a long period of recovery following this procedure.
• Total Hip Replacement: The diseased joint is replaced by an artificial one. It is recommended for treatment of advanced osteonecrosis of the hip. In some cases, only the diseased surface of the bone may be removed and resurfaced with metal.

It is important to follow instructions regarding the postoperative recovery to ensure maximum benefit from these procedures.