What is a Total Hip Replacement?

A hip joint consists of two bones - the femoral head (the ball) and the acetabulum (the socket). Usually the joint is well lubricated and the one bone can slide against the other bone with minimal friction. However, with diseased hips, the cartilage covering the surface of the bone is worn away and we now have a situation in which the bones are rubbing against each other, causing pain and limiting movement. Joints can be destroyed for a variety of reasons, but arthritis is the most common. Total Hip Replacement is a surgical procedure which involves the removal of the diseased bone and the reconstruction of the anatomy with an artificial joint called a total hip prosthesis. The components of the prosthesis are designed to act like the normal joint. There is a femoral stem - a metal component that is placed into the thigh bone, and an acetabular cup- a plastic and metal component that is placed where the socket was. There are two goals with Total Hip Replacement:

  • Reduce or eliminate pain.
  • To restore function by improving the movement of the joint.
What should you expect?

Blood Transfusion. If you are donating blood for your surgery, you will be asked to donate at least 2 or 3 units of your own blood within 35 days prior to your surgery date. This will involve scheduling an appointment with the blood bank of the hospital, or if necessary, a blood donation facility recommended by your insurance carrier or one closer to where you live (out-of -state patients). Only one unit of blood can be donated at a time, so you will need to come in for at least two visits. The blood is then stored until your operation.

If you are unable to donate blood, for whatever reason, donor blood will be used in your case, if necessary. People have expressed some concern about blood transfusion because of the risk of transmitting diseases. Donor blood is carefully screened for communicable diseases. With the new technology, the risk of hepatitis and HIV infection is extremely low. To our knowledge, disease transmission through use of donated blood has never occurred in any of our patients. However, there is no question that your own blood is the safest. Therefore, if you are able, we recommend that you donate blood for your surgery. If you're coming a long way, arrangements can be made to have you give blood locally and have it transported here for your surgery. Please be assured that blood that you give will be given back to you, if needed.

Pre-admission Testing. Within two weeks prior to your surgery, you will be asked to undergo several laboratory tests and possibly an electrocardiogram and chest x-ray. This is called pre-admission testing. This will help us to tell whether there are any conditions which might increase the risk of surgery. A physical examination, performed by your own medical doctor or hospital staff here, is also a part of pre-admission testing.

Just Before Surgery. You will not be allowed to drink or eat anything after midnight and on the morning of the surgery. In some cases, you may be allowed to take a medication you normally take in the morning with a minimal amount of water. If instructed to do so, you will need to let the admitting nurse know that you have done this.

When you come into the hospital on the day of surgery, you may have some additional x-rays that might not have been taken previously and have a physical examination by your surgeon or resident. If you have not already done so, you will be asked to sign an operative consent form to state that you understand what is being proposed and that you are in agreement that we may proceed with the operation. Just prior to surgery, an intravenous line will be started and you will be taken into the operating suite.

Anesthesia. You will be seen by an anesthesiologist on the morning of surgery. Most of our surgeries are performed under spinal anesthesia. This is a very safe form of anesthesia. It is safer than general anesthesia, which is one of the reasons why we recommend it. Spinal anesthesia disturbs the major body functions a lot less than general anesthesia. Unless there are some specific reasons why a spinal anesthetic should not be used in your case, this is our preferred method of anesthesia.

The anesthesiologist will give you some medication to make you sleepy so that you're not really aware of what's going on in the operating room. You will not be totally asleep either. However, the area that will be operated on will be totally numb throughout the operation and for several hours after the surgery.

Surgery. As stated before, the surgery involves the removal of all of the damaged bone and cartilage. This is done with saws and drills much like a carpenter uses. The next step is to prepare the bone for the prosthesis. This involves using specialized tools to make precise cuts and to shape the bone so that the prosthesis will fit properly. The artificial joint is then placed into the bone with or without bone cement. The surgery itself takes between two to three hours, depending on the complexity of your case.

Total hip prostheses can be attached to the bone using a material called methylmethacrylate or, more simply, bone cement. With proper technique, this gives an immediate fixation of the prosthesis to the bone. Another method is called biologic fixation. This method requires that the surface of the prosthesis next to the bone is porous. With time, bone grows into the pores and the prosthesis becomes an integrated part of the joint. There are advantages and disadvantages to each type of fixation. Furthermore, the type of fixation recommended to you will depend on your age, weight, and activity level.

Recovery Room. When your surgery is completed you will go to the recovery room where you will be closely monitored until the effects of the anesthesia and intra-operative medicines are decreased and you are relatively awake and comfortable.

Orthopaedic Unit. When you have completed your stay in the recovery room, you will be transferred to your hospital room in the orthopaedic nursing unit. You will be lying on your back in a comfortable position with a pillow between your legs. The pillow between your legs is designed so that you will not run the risk of dislocating the hip replacement in the initial postoperative period. If you have surgery early in the morning, you may sit up on the edge of the bed that evening. In general, all patients are out of bed within twenty-four hours and attending physical and occupational therapy. The therapists will instruct you in learning how to use crutches or a walker and being taught some of the precautions that are necessary in the immediate post-operative period. The physical therapist will answer any of your questions and will go over all of the details.

Risks. It is important that you understand that there are risks associated with any major surgical procedure and total hip replacement is no exception. These risks include the risk of death. That's true of any major surgical procedure requiring anesthesia and blood transfusion. The risk of death in our hospital for total hip replacement is in the order of 1 per 750 or 1,000 cases so that you can see that the risk is very small, but it's not 0. The specific risk for you will depend upon your general medical condition, your age, and the difficulty of the surgical procedure, but the risk of death itself is really very small.

There are, however, some other risks which are a little bit larger. For example, there is about a 1% risk that your hip will dislocate in the immediate post-operative period. This may come from an inadvertent false movement in which the socket of the hip prosthesis becomes disengaged from the ball (femoral head). In the vast majority of these cases, this can be treated by manipulation and would not require another surgical procedure. It might require some relaxation, it might even require a short anesthetic. But again, this risk is relatively small, being about 1% of all the cases that are operated on.

A major potential risk is the risk of infection. Again, in this hospital, the risk of infection is in the order of 1 per 200 cases and we do many things to keep this risk very low. You will be receiving an antibiotic on the morning of surgery and this will be continued for 24-36 hours after surgery. There are other preventive measures that will also be undertaken to reduce the possibility of infection. Inspite of the measures, a very small percentage of patients will develop an infection and that generally can be treated by antibiotics and cured. But occasionally, rarely, it might result in the hip prosthesis having to be removed. There is also some risk of an infection elsewhere in your body after the surgery settling in the hip and therefore we strongly recommend that patients who have total joint replacement take antibiotics whenever they have infections in another area. Antibiotics should also be taken prior to procedures such as sigmoidoscopy, cystoscopy and routine dental work for the first two years after surgery. For more information regarding infections and total joints click here.

There are a host of other possible complications. If you review series of several thousand you will see literally dozens of possible complications that could take place. However, these complications take place with exceeding rarity. Things such as muscle ruptures, pulling off of the tendon, injuries to nerves and blood vessels, superficial infection and opening of the wound, and other things of this nature may occur. They don't occur very often, but they can occur.

One of the things that could occur is the loosening of the prosthesis. This loosening would not happen suddenly, but it would be a gradual process and it would be characterized by discomfort. In most instances, if a prosthesis becomes loose, it can be corrected but that usually means further surgery. Now what is the nature of this risk? That depends on several circumstances. We think in general, it's probably a cumulative risk of about 1% per year, so that if you have your prosthesis for 20 years, the possibility of loosening over that 20 years could be as high as 1 in 5. If you have your prosthesis for 10 years, it could be 10%.

Activity. To a certain extent, what the patient needs to realize is that an artificial hip can never be as good as a normal hip. There is always the potential that it may get infected at some date in the future. It will not tolerate the same kinds of physical stresses that the normal hip will tolerate. We strongly recommend against physical activity such as tennis, running, contact sports, things that can contribute to loosening of the hip through a physical process and the physical force applied to the hip that results in motion between the prosthesis and the bone and loosening and pain. But this is the reason that one has to be cautious about actually performing a total hip replacement and why it should only be applied tothose patients who have severe symptoms.