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| Hip Resurfacing | |
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Surface replacement of the hip is an alternative to traditional hip replacement for the treatment of conditions such as osteoarthritis, avascular necrosis, and post-traumatic arthritis. It provides a bone-conserving hip replacement and is best suited for young, active patients. The hip joint can be thought of as a ball and socket joint. When arthritis has developed on both the ball and the socket, a hip replacement may be recommended. A hip replacement involves the removal of the arthritic bone and replacing the ball (femoral head) and socket (acetabulum) with artificial parts. The difference between a traditional hip replacement and a surface replacement lies in the way the ball is replaced. With both traditional hip replacement and surface replacement, the socket is inserted in a similar fashion. The two procedures differ in the way the femur is prepared. Whereas traditional hip replacement involves removing the head and neck of the femur, surface replacement preserves this bone (see picture). With a traditional hip replacement, after this bone is removed, a prosthesis with a stem is inserted within the thigh bone. With a surface replacement, the preserved bone is sculpted to accept a metal cap with a short stem. Traditional Total Hip Hip Resurfacing The preservation of bone has several advantages. The first is that more bone is retained in the femur, should another hip replacement become necessary. Over time, any hip replacement may loosen or show signs of wear. In a young, active population, there is a high likelihood that more than one hip replacement operation will be necessary over the lifetime of the patient. It is a well documented principle that the more bone that remains during a revision hip operation, the greater chances of success. The second advantage to a surface replacement is that the preservation of bone allows for a much larger ball size. This allows for an increased range of motion of the hip and greater stability. After surface replacement of the hip, patients are usually able to return to high range of motion activities, such as dancing, rock climbing, and martial arts. The dislocation rate after surface replacement of the hip is about 10 times lower than for a traditional hip replacement. Also, because of the way the surface replacement is placed on top of the bone, it also allows for a return to impact activities like jogging, tennis, and basketball. With a traditional hip replacement, these activities are best avoided. People may also return to skiing, golf, cycling, hiking, and swimming without difficulty. Studies have also demonstrated an increase in bone density in the bone around a surface replacement, as compared to a traditional hip replacement. Advantages of surface replacement
The procedure The hip resurfacing is performed in an orthopaedic operating room which helps reduce the chance of infection. Your surgeon will be wearing a "spacesuit", also designed to reduce the chance of infection. The entire surgical team will consist of your surgeon, two to three assistants, and a scrub nurse. The anesthesia for a total hip replacement is regional anesthesia with a spinal and/or an epidural catheter, which is a small tube inserted into the back. This is the same type of anesthesia given to women in labor. You will be made numb from the waist down so that you will not feel anything. The catheter stays in for 1-2 days after the surgery to help with your post-operative pain control. During the course of the operation, you can be as awake or as sleepy as you want to be. After the anesthesia is administered, you will be placed on your side. The incision for a total hip replacement is made along the side of your hip. The incision will measure anywhere from 5 to 10 inches depending upon your anatomy. It is well-covered by undergarments and is usually not visible when wearing clothes. The arthritic ball and socket are exposed and sculpted to accept the resurfacing implant. The socket is placed into the body without cement; over time your bone will grow onto the socket. The resurfacing ball is inserted with cement. During the closure, two drains may be inserted around the operated area to assist with evacuation of blood. Staples are used to close the skin. The entire operation will take from 1.5 to 2 hours. Afterwards, you will be brought to the recovery room, where your blood work will be checked, and an x-ray of your new hip will be taken. Most patients can be brought to a regular room within a few hours; others will need to stay overnight in an intensive care unit, as determined by your surgeon and anesthesiologist. Patients generally stay in the hospital for 2-4 days following hip resurfacing surgery. General Risks of Hip replacement surgery Some of the risks of surgery of the hip include the loss of blood, formation of a clot in your leg, and the chance of infection. The overall incidence of these risks is very small. They should be discussed with your surgeon prior to proceeding with the operation. Some of the risks of having a prosthetic hip include the chance that the ball will dislocate (come out of the socket), the parts may loosen or wear out over time, or the prosthesis may become infected. As the hip prosthesis is a foreign body, it may become infected when there are bacterial infections elsewhere in the body. It is important for patients to be aware of this possibility and make other physicians and dentists aware about the presence of a hip prosthesis. Again, these issues will be discussed with you by your surgeon. Longevity A hip replacement has a lifespan much like anything with mechanical parts. Its longevity depends upon a variety of factors, including patient weight, patient activity, and mechanical properties of the prosthesis. The question of how long a prosthesis will last has been studied in detail over the years. The current generation of hip resurfacing implants has not been around long enough to be able to predict how long they will last. Risks specific to surface replacement Metal ion dispersal The current generation of surface replacements are metal-on-metal bearings. That means both the ball and the socket are made entirely of metal. Although this cuts down dramatically on wearing out of the components, it has been shown to cause metal ions to be dispersed through the body. Cobalt and chromium ions are measurable in the blood stream, but have not been shown to cause cancer or any other disease in humans. Although the metal ions are measurable, no one knows what a safe level is. Generally, people with functioning kidneys are able to excrete the ions in their urine. Femur fracture Because the bone of the femur is retained, it is possible to fracture it after surface replacement. Most of the fractures occur early in the post-operative period if too much weight is put on the leg too early. The body needs time to adapt to the new prosthesis. Post-operatively, crutches are used for 4 weeks to protect the amount of weight put on the leg. With current techniques and rehabilitation protocol, the risk of fracture is less than 5%. Nerve injury Working around the bone of the femur may cause extra pressure to be put on the nerves in the hip area. This may cause weakness of some of the muscles of the leg in less than 1% of cases. Heterotopic ossification The hip resurfacing procedure may lead to extra bone forming around the hip, leading to stiffness, called heterotopic ossification. We now take measures to prevent this, using one dose of radiation to the hip area after surgery. The radiation treatment, known as XRT (external radiation therapy), is performed in the first 2 days after surgery and does not have any association with cancer. With XRT, the risk of extra bone forming is less than 2%. Pre-operative orientation Most patients will be asked to donate 1 pint of their own blood in the weeks preceding hip resurfacing. This helps reduce the need for a blood transfusion from our blood bank. Almost all of the patients will receive the donated blood as a transfusion after surgery. Rarely, an additional transfusion is necessary from our blood bank. The blood from the blood bank is carefully screened to the best of our ability to detect any infectious diseases. You will be asked to see a medical doctor prior to your surgery. This is a precaution to make certain that you are healthy enough to undergo hip replacement surgery. In the course of this workup, you may be asked to have additional testing to examine your heart and lung function. Post-operative course Immediately after hip resurfacing surgery, you will be in the recovery room. Most patients are able to go to a regular room after a few hours, when the sensation returns in your legs. You will be given a pain pump which will allow you to control when you are given pain medicine. Most people are quite comfortable with the pain pump in place. On the day of surgery, you may do some of the exercises as instructed by your physical therapist, including buttock clenches and moving the feet up and down. You will be allowed to take some ice chips after surgery to wet your mouth, but drinking liquids or eating may cause you to become nauseated. You will have a catheter in your bladder so that you do not have to worry about urinating. Following the surgery, this is mainly a day of rest. The first day after surgery will have a lot of activity. You will meet our physiotherapists, who will instruct you in more exercises to perform while in bed. In addition, they will help you stand today and take a few steps with a walker. You will be taught the positions to avoid with a hip replacement, as well as the safe positions. Generally, you will be allowed to drink clear liquids today. In the next few days, you will find it easier and easier to move about. You will be freed up from the pain and urinary catheters. Pain medication will be given in the form of tablets. Eventually you will progress to walking with a cane or crutches. On the second day after surgery, if your bowels have shown evidence of recovery, you will be allowed to eat regular food. You will be discharged home when you have demonstrated that you can get in and out of bed and walk safely. A physiotherapist will come to your house to continue rehabilitation. A case manager will discuss these options with you and help you plan for your eventual return home. Your return to activity will be guided by your surgeon and therapists. Generally, patients are able to walk as much as they want by 6 weeks post-operatively. Patients are able to resume driving at 6 weeks. At 8 weeks, patients are able to resume playing golf and swimming; at 12 weeks, they may play tennis. Your surgeon will help you decide what activities you may resume. Frequently Asked Questions General Questions Q: What is arthritis and what causes it? A: Arthritis is an umbrella term for a number of disease entities in which the joints become inflamed and the cartilage that lines the bones deteriorates. Eventually, bone on bone wear occurs. As the disease progresses, patients often experience pain, stiffness, and disability. The vast majority of people diagnosed have osteoarthritis and in most cases the cause of their condition cannot be identified. One or more joints may be affected. Rheumatoid arthritis (and other forms of inflammatory arthritis) is a disease that affects the entire system and multiple joints. This type of arthritis is an autoimmune disorder in which the body perceives the cartilage to be a foreign substance and attacks it. Q: If I have arthritis in one hip, will I get it in the other? A: If you have been diagnosed with osteoarthritis, having an affected hip does not mean that you will develop arthritis in the opposite hip. About 40% of patients who have osteoarthritis in one hip will have the same condition in the other hip. In contrast, patients with rheumatoid arthritis often develop problems in both hips. Q: Can I have joint replacement on both hips at the same time? A: Yes, healthy patients in their 60s or younger, with no cardiopulmonary disease may be candidates for such surgery. Your orthopaedist can tell you more about what is involved. Q: What is a prosthetic hip made of? A: The implant for a hip resurfacing is composed of 2 parts: the ball and the socket. The resurfacing ball is made out of metal, usually cobalt-chrome, and is placed as a cap on top of the thighbone. The socket is also made of cobalt-chrome and inserted into your pelvic bone. Q: Will my new hip set off the metal detector at the airport? A: While hip implants generally do not set off metal detectors, more sensitive machines may register the presence of the implant. We give our patients cards to show at the airport that explain that the bearer has received a hip implant containing metal.
Losing weight will decrease the forces across the hip joint and may make the arthritis pain more bearable. Q. Why should I have my hip resurfaced?
Q. What kind of anesthesia is used? A. Most total hip replacements at Pinehurst Surgical are performed under regional anesthesia. It is called a spinal and/or an epidural block, which is the same kind of anesthesia given to women in labor. The regional anesthesia provides numbness from the waist down, so there will be no pain during surgery. In addition, patients are given a light sedative to make them as sleepy or awake as they want to be. Q. How long will I be in the hospital?
Q: How soon after surgery can I resume driving? A: Most patients can resume driving at six weeks after surgery. Hip resurfacing specific questionsQ . Why should I have a hip resurfacing vs. a traditional total hip replacement?A. A hip resurfacing and hip replacement are both designed to improve your activity, function, and decrease your pain. The difference lies in the way this is accomplished. For some patients, there is a large difference between a hip resurfacing and a hip replacement because of your age and activity level. For others, there is not such a large difference. For example, a young patient who may outlive his/her first hip replacement may more willing to have a hip resurfacing because of the preservation of bone. A patient who would like to return to impact activities or activities requiring a high range of motion will have a greater benefit from a hip resurfacing. On the other hand, a low-demand patient for whom a total hip replacement can last the rest of his/her life would be a better candidate for a traditional total hip replacement. Q. What are the specific risks of hip resurfacing? A. The general risks of hip resurfacing are the same as with traditional total hip replacement. These include infection, dislocation, blood clots, nerve injury, and extra bone formation around the hip that could make the hip stiff. The risk of infection with hip resurfacing is no different than with total hip replacement. The risk of dislocation is 10x lower, because of the larger diameter ball. The risk of nerve injury and extra bone formation around the hip are slightly higher with a hip resurfacing because of the need to work around your bone in an enclosed space. A risk unique to hip resurfacing that is not present in traditional hip replacement is that of femoral neck fracture. The femoral neck is a vulnerable area of bone that connects the ball of your hip joint to the rest of your thighbone. When elderly people fall and "break their hip", this is the area that breaks. With a traditional hip replacement is done, this bone is removed, so it cannot break. With a hip resurfacing, the femoral neck is preserved, so there is a risk of fracture. We believe the risk of fracture in this area is between 1-2%. It is because the surgical exposure, preparation of bone, and placement of the component with cement may cause this bone to be more vulnerable.
Q. What will happen when the hip resurfacing wears out? A. When a hip resurfacing wears out, it is generally because the femoral cap loosens from the underlying bone. If this happens, it can be converted to a traditional total hip replacement with a stem in the thigh bone, utilizing a big metal ball to match your socket. Generally, the socket is firmly attached to your bone and will not need to be revised. The end result is a metal-on-metal hip replacement with a big metal ball. Q. What are the major benefits of hip resurfacing? A. The major benefit to resurfacing compared to traditional replacement is the preservation of bone. For patients who may outlive their implant, I see this as the largest advantage. Since bone is preserved at the initial operation, more bone is available for the next operation. A hip resurfacing also has a larger diameter ball, which gives a greater theoretical range of motion. It is also more stable, so the dislocation rate is lower. Additionally, a hip resurfacing loads the bone of the femur the way it is in your own hip, so we believe you can return to more impact activity. Q. Should I be concerned about the metal ions that are released into the blood? A. This is a controversial topic. There have been many studies looking at this issue, and none have been conclusive. People with healthy kidneys seem to excrete the metal ions in the urine. Metal/metal hip replacements have been around since the 1970’s, and they have never been linked to an increase in cancer or other diseases. We do not know "safe levels" of these metal ions in the blood, nor is it likely that we will be able to determine "safe levels" in the near future. It is not advisable to perform metal/metal hip resurfacing in patients on dialysis, kidney transplants, or with renal failure. Surgical Q: How long will the replacement last? A: Because the current generation of surface replacements have only been in use for the last 5-8 years, it is not known how long it may last. Because of the high activity demands of its targeted population, it has a high chance of needing another operation in the future. When the surface replacement fails, it is generally by loosening of the ball portion. In that case, the bone and implant can simply be removed, and a traditional hip replacement can be inserted. There are matching balls that could mate with the existing socket.
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