Total Hip Replacement (Arthroplasty)

What is hip arthroplasty?

More than 300,000 total hip replacements are performed in the U.S. each year. That number is expected to increase to 500,000 by the year 2030. The hip and knee replacement specialists at Midwest Orthopaedics at Rush perform more of these procedures than any other group in the Chicago area.

Total hip replacement (arthroplasty) is performed when the hip is causing significant pain, a compromised lifestyle and has deteriorated past the point where more conservative procedures might be effective.

During the procedure, the surgeon removes the damaged cartilage along with some bone and replaces this with an artificial hip joint (prosthesis). The prosthesis consists of two parts; a round ball (femoral head - secured into the center of the upper femur with a stem), which rests in the cup-like acetabular component (socket) placed in the pelvis.

Who is a candidate?

Ninety percent of the hip replacement patients have osteoarthritis. This occurs when the cartilage that lines the hip's ball-and-socket joint deteriorates, often due to progressive wear-and-tear. As healthy cartilage deteriorates, the bone rubs against bone, which causes pain.

The remaining ten percent of patients require hip replacements due to other types of arthritis, bone tumors, trauma and other conditions, such as osteonecrosis.

Children are not candidates for hip replacements because their bones are still growing. While doctors recommend children wait until age 18, occasionally younger individuals may require hip replacement.

What are the different ways to perform a total hip replacement?

As part of a hip replacement surgery, a surgeon will need to access the hip joint to replace the ball and socket. There have been many different surgical approaches described for accessing the hip joint and surgeons use different surgical approaches based on their own experience and preferences.

Basically, there are two ways of performing hip replacements - via the posterior and anterior approach. The posterior approach involves entering the hip socket from the back (posterior) of the hip area. During the anterior approach to surgery, the doctor enters through the front of the hip area.

There are advantages and disadvantages to both approaches. However, the most important aspect of a surgical approach to the hip is that it allows the surgeon to safely insert the hip components so that a hip replacement will function well for a long time. 

Anterior Approach to the Hip
While popular recently, the anterior approach to hip replacement has been used by qualified surgeons for many years. The main advantage to the anterior approach to hip replacement is that it results in a smaller incision scar and carries a lower risk of dislocation (the hip popping out of the socket). The main disadvantages are a higher risk of damaging the muscles that stabilize the hip joint, which can lead to a limp, and the possibility of a patch of numbness on the thigh. When performed by a skilled surgeon, this approach is compatible with a rapid recovery.

Posterior Approaches to the Hip
The posterior approach is the one used most commonly by surgeons in North America. The main advantages are its simplicity and a lower risk of damaging the muscles that stabilize the hip joint. Its main disadvantage is that it carries a higher risk of dislocation. When performed by a skilled surgeon, this approach is compatible with a rapid recovery

Much of this material may be confusing and it can be controversial among surgeons. All of the surgeons at Midwest Orthopaedics at Rush have the experience and skill to allow for a rapid and safe recovery with as little pain as possible. They have performed thousands of hip replacements, have trained hundreds of other joint replacement surgeons from across the country and are experts in these procedures.

To determine which approach is best, patients should discuss this issue with their doctor.

What materials does the doctor use?

Components of a Hip Replacement
The hip replacement procedure replaces two components of the hip joint. The ball portion, the upper part of the femur (femoral head) is removed and replaced with a ball made of either metal or ceramic which is attached to a metal stem that is fitted into the femur. The socket portion of the joint (located in the pelvis- acetabulum) is also replaced using an artificial socket made of metal, which can be lined with either plastic or ceramic.

Implant Materials
Several different materials are typically used as part of a hip replacement. There are advantages and disadvantages to most of these materials and your physician will discuss with you the implant material that will best fit your needs.

Cemented and Cementless: The hip implant is held in place using one of two fixation methods, cemented or cementless. Cemented fixation uses a bone cement that cures over several minutes in order to fix the implant to the underlying bone. Cemented fixation is rarely used today in North America except in the elderly. Cementless fixation is obtained with a metal implant that has a roughened or porous surface which allows bone to grow into the surface of the implant. This is the preferred method for most physicians.

Metal-on-Plastic Implants: The ball portion of the metal-on-plastic implant is made of a cobalt/chromium-based alloy ball attached to a stem made of titanium or cobalt/chromium-based alloys. The metal ball portion fits into an ultra-high, molecular weight, polyethylene plastic socket which is implanted into the pelvis. This is the most commonly used bearing combination in North America and works well for most patients. In some cases, a surgeon may choose to match a ceramic ball to the plastic liner

Ceramic-on-Ceramic Implants: In this combination, the ball portion of the ceramic-on-ceramic implant is made of ceramic materials (aluminum oxide or zirconium oxide) and attached to a stem made of titanium or cobalt/chromium-based alloys. The ceramic ball portions fits into a socket made of the same ceramic materials and implanted into the pelvis. Ceramic materials are very hard, making it a good bearing surface which can sustain wear. Ceramics, however, can break or crack. Patients have also reported squeaking coming from these bearings.

What is RSA technology?

Some Midwest Orthopaedics at Rush physicians will incorporate radiostereometric analysis (RSA) as part of a patient's joint replacement surgery. RSA is a very precise technique for monitoring if a patient's hip or knee implant is wearing down or moving. RSA is a technology that uses X-rays taken from various angles creating a "stereo" or three-dimensional image.

How does RSA work?

RSA works by implanting tiny biocompatible markers, also known as RSA beads, in the bone surrounding an implant during surgery. These markers act as reference points in follow up X-ray exams. The markers are able to tell researchers and physicians how an implant migrates relative to the bone over time and can be indicative of short- and long-term implant stability.

What are the benefits of RSA?

RSA helps physicians determine a hip or knee replacement patient's progress which can be important if the patient is experiencing joint pain down the road. RSA also provides research for future implant design and insight into the safest and most durable materials for implants.

What should the patient do to prepare for hip replacement surgery?

Before scheduling surgery, the patient will meet with one of the Midwest Orthopaedics at Rush joint replacement specialists for an initial consultation. He will then return for a day of pre-operative testing and education about the procedure. Testing includes a blood test, an X-ray and sometimes magnetic resonance imaging (MRI).

The day before surgery, the patient cannot eat anything after midnight. The day of surgery, the patient typically arrives at the hospital in the morning. He should arrange for a friend or family member to drive him home after surgery.

Before surgery, the patient may get a general anesthetic, but the vast majority of patients do not require this type of anesthesia. Most patients are treated with a spinal or epidural anesthetic which is performed along with sedative medication through an IV in the arm.

The patient and family should prepare the home for his post-op recovery and arrange for someone to bring meals and pick up medications from the pharmacy for the first few days after surgery. Set aside a comfortable chair, with a side table and extra pillows, where the patient has easy access to things like a television remote controller, medications and telephone.

What should the patient expect after surgery?

After hip replacement surgery, the patient will be moved to a recovery room until he wakes up from anesthesia, then transferred to a hospital room.

Recovery is highly dependent on the individual. After hip replacement surgery, the patient usually stays in the hospital for anywhere from one to three days. In some cases, the patient may return home the same day. People who are seriously deconditioned or who have multiple medical conditions may initially be discharged to a rehabilitation facility. However, most recover at home for a few weeks before returning to normal activities. A return to Midwest Orthopaedics at Rush for a check-up two to three weeks after surgery is standard.

In most cases, the physician will prescribe pain medication as well as medicine to help prevent blood clots. The patient should avoid getting his incision wet for several days after surgery and should call the doctor immediately if there are signs of infection, which include chills, fever and drainage from the incision.

Some patients are more comfortable at night if they wedge a pillow between their legs while sleeping. The sooner the patient is able to exercise after hip replacement surgery, the better. Physical therapy is usually recommended to help the patient recover full range of motion.

Most patients enjoy a full recovery from hip replacement surgery over a period ranging from several weeks to several months. Athletes can frequently return to their games. However, some restrictions may be placed on physical activity. The patient returns to Midwest Orthopaedics at Rush for an annual check-up.

While traveling, a patient with an artificial hip with metal components can set off metal detectors at airports, so the doctor can issue a card which confirms that he has this prosthesis.

What are the risks?

Hip replacement is major surgery, so it includes risks common to most surgeries. This includes reactions to anesthesia, possible hearts attacks and stroke. Complications can include blood clots, pulmonary embolisms, infections, rotation of the leg, bone fractures, blood accumulation in the hips, nerve or vascular injuries, numbness, scarring or chronic pain.

Rarely, the ball comes out of the socket, which is called a dislocation. Usually, the doctor corrects this without surgery.

The length of the leg is almost always altered by hip replacement surgery. In most cases the arthritic process shortens the leg and the surgery restores its length. If one leg is slightly longer than the other after surgery, the doctor may prescribe a shoe lift.