Hip Replacement

Definition

A surgical operation to replace the hip joint.

Description

Time, coupled with arthritis or injury, can lead to degeneration of the hip joint, causing pain and restricted movement. Hip replacement surgery, also called total hip arthroplasty (THA), may be an option if your daily activities are limited by uncontrollable pain.

Pain relief and increased mobility are the hallmarks of hip replacement surgery. For more than 25 years, hip replacement has taken people off of crutches and out of wheelchairs, restoring many to a near-normal, painless lifestyle. In the U.S., more than 100,000 hips are replaced each year. The operation is by far the most successful surgery for treating advanced arthritis of the hip.

The most common reasons for surgery are:

Osteoarthritis: Generally attributed to wear and tear with age, osteoarthritis is a gradual deterioration of the cartilage that cushions bones within a joint. As cartilage wears away, surrounding joint structures grow irregularly and can become inflamed and painful. Eventually bone can begin to rub against bone.

Rheumatoid arthritis: Inflammation of the tissues surrounding joints leads to worn and swollen joints. This disease may eventually lead to deterioration of cartilage and destruction of joints.

Osteonecrosis: An acute injury to your joint, such as a severe blow or fall, can disrupt the blood supply to the upper portion of the thighbone. This causes rapid deterioration of the joint. Eventually, the weight-bearing surface of the bone may collapse or fracture, leading to chronic pain. This condition can also occur with alcoholism and long-term use of cortisone-like drugs.

Hip disorders or fractures: Hip replacement surgery is also used to repair disorders and fractures of the hip.

Procedure

Surgical Procedure

All hip implants work as a ball-in-socket joints and consist of two main pieces. The thigh component is a metal shaft with a metal or ceramic ball at the top end. The ball fits into a cup-shaped socket made of a tough, moldable plastic (polyethylene), usually encased in metal.

During surgery, the surgeon removes the top of the thighbone (femur), drills a hole in this bone for the thigh component, and then shapes the socket in the pelvis for the pelvic implant. The thigh piece is then secured into the natural shaft of the thighbone and the socket into the lower pelvis. Replacing the diseased joint with an artificial one eliminates the source of the pain.

Cemented Versus Cementless Hips

After more than three decades, cemented hips have a proven track record. About 85 percent of people can still walk and move comfortably 15 years after surgery. But cracking of the cement after several years does cause some implants to loosen.

Because of this problem, bone surgeons designed a cementless joint in the early 1980s. In a cementless implant, a roughened, porous surface allows bone to grow directly into and around the prosthesis. Yet cementless hips can also loosen. In fact, early data show a higher incidence of thigh pain and loosening of the thigh implant in the cementless hip vs. the cemented model.

Over time, both types of artificial joints create debris caused by friction and wear. The shedding of particles can cause irritation that destroys bone and ultimately contributes to loosening. Experts believe the cementless implants may be more vulnerable to the breakdown of particles than cemented ones.

Orthopedic surgeons generally choose a cementless implant for adults younger than 50. In younger people, bone growth into the porous part of the implant is usually more robust than in older adults. Cemented hips fail more frequently in young adults because cement often cannot withstand a higher activity level.

If you are between 50 and 70, you may receive a "hybrid hip," a cemented thigh component and a cementless pelvic piece. If you are older than 70, you are likely to get a totally cemented hip.

Over the long term, the site of hip replacement is susceptible to infection. Each time you have dental work, simple surgery, a catheterization or a bacterial infection, you should take a course of antibiotics to reduce the risk of hip infection.

Questions to Ask Your Doctor

Is a hip replacement needed in this case?

Why is it necessary?

Do you recommend a cemented or cementless joint?

What are advantages and disadvantages of each?

How soon after surgery can I resume normal activities?

Will I regain the full range of motion?

Should I take antibiotics when I have dental or other minor surgery?

What is the life expectancy of the artificial joint?