Frequently Asked Questions: Total Hip Arthroplasty
Jeffrey M. Nakano, MD www.rmodocs.com 970.242.3535
Rocky Mountain Orthopaedic Associates
Introduction
Total hip arthroplasty is a procedure that was developed in the 1960’s in order to alleviate the severe pain associated with arthritis of the hip joint. Over the years the technique has been improved and now it is truly one of the success stories of modern medicine.
General Questions
How will I know when it is time for me to replace my arthritic joint?
Total hip arthroplasty should be considered if x-rays demonstrate significant destruction of the joint due to arthritis and if nonsurgical treatments have failed. Nonsurgical treatments would include activity modification such as using a cane, weight loss (if you are significantly overweight), use of arthritis medications, gentle exercise to maintain muscle tone and joint motion. Surgery is considered when you feel that your symptoms are significantly interfering with your enjoyment of life.
What will I be able to do physically after my hip is replaced?
It is important to have realistic expectations of your total hip arthroplasty. A successful hip replacement will enable people to return to the routine activities of daily living with a significant reduction in their level of pain. There are certain restrictions, however. Jogging, jumping from heights greater than one or two feet, and other impact loading should be avoided. Tennis and racketball are not advised, but golf, swimming, and bicycling are reasonable pursuits. Skiing (but not mogols) is a reasonable activity. The extreme hip positions associated with some yoga maneuvers are not recommended.
Can both of my arthritic hips be replaced at the same time?
The simple answer to this question is yes. However, nearly every study that has looked at this question has shown that there is an increased risk associated with having both hips replaced at the same time. I would certainly not recommend this unless both hips are quite bothersome. In addition, I would not recommend that both hips be done at the same time in any patient over the age of 75, or in any patient with significant heart or lung problems.
What is the prosthesis made of?
The femoral component (the part that supports the ball) is typically made of titanium. The acetabular component (socket shell) is usually titanium.
What types of bearing surfaces are available? In other words, what materials are the ball and liner of the socket (socket liner as opposed to socket shell) made of.
Bearing surfaces can be metal ball/polyethylene (plastic) liner, ceramic ball/ceramic liner, ceramic ball/polyethylene liner, or metal ball/metal liner. Unfortunately, there is no source available that will allow you to make a decision about the best combination for you. Plastic liners will wear (though many can last more than 20 years), and it is felt that the plastic wear particles may lead to bone destruction. Ceramic components have been subject to squeeking and rare episodes of breakage. Metal liners may produce wear particles that cause cancer in laboratory animals, but this has never been shown to have occurred in people with metal/metal bearing surfaces. There have been instances of metal hypersensitivity, but these are relatively rare.
What is a “surface replacement” artificial hip?
This is a type of artificial hip that allows you to preserve more of your own thigh bone (femur). This type of hip prosthesis has been available in some form since at least the 1950’s. Newer versions have been developed that will hopefully last longer than those in the past. However, it is generally thought that for most patients this will be an interim procedure, and that eventually a more conventional artificial hip will be required when the hip resurfacing procedure fails. It is felt that the procedure is best done in certain women and men under the age of 55 or 60.
How long will my artificial joint last?
The failure rate is about 1% per year for the first 20 years for the average 65 year old patient who receives an artificial hip. After 20 years the chances that the hip will be functioning are in the 80% range. If you are younger and more active or heavier, the failure rate is higher. Extensive data does not exist for longer follow up periods, but like any mechanical device, the failure rate probably increases with time.
Do you operate at St. Mary’s Hospital and Community Hospital?
Yes, I operate at both hospitals, but the great majority of my surgeries are done at St. Mary’s Hospital where I have specific surgery days every week that are reserved for my patients. In addition St. Mary’s has a separate floor of the hospital dedicated to the care of only orthopedic patients, and the nurses on that floor are very skilled at taking care of orthopedic patients.
How large is my incision going to be?
The incision will typically be between 4 and 8 inches depending on the size of the hip and the amount of surrounding tissue. I feel that the incision needs to be as large as necessary to implant the artificial hip accurately.
What are the main complications?
Infections will occur in 1-2% of cases, whether the surgery is done at St. Mary’s Hospital or the Mayo Clinic. Great care is taken to try to prevent bacterial contamination of the wound, but since these organisms are present in the air around us, we cannot always be successful. If infection does occur, further surgery and hospitalizations will probably be necessary. Often, the prosthesis will have to be removed initially, and then replaced when the infection has been cleared by taking appropriate intravenous antibiotics.
Loosening is another complication. A successful hip replacement depends upon a good bond between the bone and the artificial hip components. If this bond loosens, the hip will be painful and may have to be replaced. This bond can be achieved with a type of cement that holds the prosthesis to the bone or, more commonly, it can occur by allowing the bone to grow into a specially treated surface on the prosthesis. Unfortunately, loosening can occur whichever method is used. Risk factors such as large body weight, young age at the time of hip replacement, or excessive impact activity will lead to higher loosening rates.
Dislocation of the prosthetic ball from the socket is another possible complication. Prior to artificial hip surgery, the muscles and ligaments that surround the real hip keep this from occurring. However, it is necessary to cut through some of these muscles and ligaments in order to implant the artificial hip, so this makes the hip more likely to dislocate. If dislocation does occur, the pain is so significant that an ambulance is usually necessary to make the trip to the emergency room. Fortunately, the hip ball can usually be placed back into the socket without surgery, but sometimes the hip will continue to dislocate and surgery will have to be performed to prevent this from recurring. I typically use an antero-lateral approach to the hip joint because artificial hips done in this fashion are more stable, and the dislocation rate is under 1%.
Unequal leg lengths often exist prior to surgery. Sometimes people are born this way. Usually, the arthritic hip gradually becomes shorter than the normal hip. At the time of surgery, every attempt is made to try to equalize the length of the legs. However, most people feel the operated leg is longer than the other leg when they first start walking in the hospital after surgery, even when they are equal. I have to admit, I have a tendency to make the operated leg slightly longer since this usually makes the hip more stable and less likely to dislocate.
Another complication is blood clots that can form in the blood vessels of the leg and pelvis. While this problem can cause pain and swelling in the leg, it is the potential for the blood clot to break off and go to the lungs and compromise breathing that makes this complication potentially serious.
In an effort to fit the prosthesis as closely to your bone as possible to maximize the chances of boney ingrowth, your femur or socket may suffer an intraoperative fracture. Usually, we will be aware of this problem and fix it at the time of surgery. This may affect your weight bearing status in the first few weeks after surgery (often it does not), but usually does not produce any long term problems.
Other possible risks include nerve or blood vessel injury and disease transmission (AIDS, hepatitis) via blood transfusions (though that risk is now felt to be less than 1:1,000,000.
What measures do you take to try to prevent infection?
Infections after artificial hip[ surgery are a risk of the surgery, just as an automobile accident is a risk of driving. I use perioperative antibiotics, laminar flow operating rooms (special operating rooms that have a high air turnover rate), and so-called “space suits” that prevent bacterial shedding onto the surgical field from the surgery team. It has also been shown that limiting the traffic in and out of the rooms is helpful, and we try to do this as much as possible We require preoperative dental and physical examiniations to determine if there are factors present that might increase your risk of infection. The hospital provides special skin cleansing agents to be used just prior to surgery to further decrease the risk of self contamination.
What measures do you take to try to prevent DVT (Blood Clots)?
Blood clots that go to the lungs and cause a pulmonary embolism can be a very serious consequence of surgery. You will typically be on two or three forms of anticoagulation during your hospitalization: 1) mechanical foot pumps, 2) Lovenox (enoxaparen) shots in the skin over your stomach, 3) Coumadin (warfarin) pills. In addition, pointing your toes and foot upward and downward and contracting your calf muscles at every opportunity will be helpful in preventing clots. When you leave the hospital you will continue on either the Coumadin pills or the Lovenox shots. There is no data to support one form of treatment over the other at this time. If you take the shots you will be on the medication for 7-10 days after surgery. If you take the pills, you will be on the medication for 3-4 weeks after surgery. After you finish the pills or shots, you should take one aspirin (81 or 325 mg) per day if you can tolerate it. If your insurance does not pay for prescription drugs, I would recommend Coumadin pills over Lovenox shots, since there will be a lot less out of pocket expense. If you are on Coumadin, you will have to visit the coagulation management (Coumadin) clinic (entrance 22 at the Pavilion) every several days to monitor your level of anticoagulation. This is not necessary, if you are on the Lovenox shots.
Before the Surgery
What do I need to do to get ready for the surgery?
1. If you haven’t seen your primary care physician for a while, you will probably need to see him/her. Your internist or family practice doctor will check your heart and lungs to make sure you are in good shape for the surgery. This visit should take place at least a couple of weeks (and preferably several months) before your operation so that steps can be taken to evaluate and correct any abnormalities.
2. If you haven’t seen your dentist in the past few months, or if you contemplate a visit to your dentist in the 4 months following your surgery, you should see him/her prior to the surgery. This is necessary to make sure there are no occult pockets of infection around your teeth that may spread bacteria through the bloodstream to your new joint.
3. Some patients will wish to donate their own blood to the blood bank so that they can get their own blood back after surgery, if they require a transfusion. The risk of getting a disease such as AIDs, hepatitis, and CMV is less than 1:1,000,000. The risk of major transfusion reactions is similar whether you donate your own blood or not. The odds of having a transfusion for a total hip are less than 10%. In addition, your donated blood will be discarded if it is not used. For all these reasons, I no longer recommend giving your own blood before surgery.
4. You will have some lab work done prior to surgery. A urine test and an EKG (to measure heart function) will generally be done as soon as you schedule your surgery. A blood count, chemistry profile, and other blood tests will be done about 28 days prior to your surgery. Any abnormalities on these tests may require further evaluation. Often, we will obtain screening lab work 6 or more weeks prior to your surgery. If there are abnormalities, we will have plenty of time to correct them prior to your surgery. Unfortunately, some of the lab work will have to be repeated in the month prior to your surgery, since it will be outdated.
5. Pre-operative physical therapy can be helpful, particularly if you are deconditioned due to your arthritic joint.
6. If possible, stop taking aspirin and arthritis pills like Motrin, Naprosyn, Aleve, Advil, Ibuprofen, etc. one week before surgery. This may decrease your intraoperative and postoperative blood loss. Some anticoagulants like Coumadin, Plavix, Aggrenox, and Persantine, and some herbal medications should be stopped prior to surgery also. Some medications that are taken for rheumatoid arthritis like methotrexate and Remicade must be stopped prior to surgery. Continue to take blood pressure and heart medications until the morning of surgery (with just a sip of water on the morning of surgery). If you are taking aspirin for known coronary artery disease, you should continue to take the aspirin right up to the day of surgery. Tylenol (acetaminophen) and narcotic pain medications are permitted until the time of surgery.