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Mark E Endicott M.D. 2801 K. St Suite 500 Sacramento, CA 95816 (Phone) 916-733-8710 TOTAL KNEE REPLACEMENT: BENEFITS, RISKS, AND ALTERNATIVES by: Mark Endicott, MD INTRODUCTION If you are contemplating having a total knee replacement, I feel you should know the facts as much as they are known about the expected benefits, as well as, the risks and possible complications of the procedure. This information booklet is designed to review these facts with you, so may make a more intelligent decision regarding surgery. NON-OPERATIVE TREATMENT In my opinion, total knee replacement is not a conservative operation. In the procedure your bone and joint is removed and it is replaced with plastic and metal components. You become dependent on the function of these components and any failure of the components can result in pain and loss of function. I feel you should exhaust all reasonable non-operative measures to control pain and maintain function prior to considering total knee replacement. Arthritis of the knee is by definition a wearing away of cartilage. The cartilage that lines the knee is an exceptional material. It is smoother than any man made bearing. The cartilage has no nerve endings in it and therefore, any motion between cartiliganious surfaces does not cause pain. As the cartilage wears away, however, debris is generated which causes an inflammatory response which produces pain and also accelerates the destruction of the 2 joints. The underlying bone does have nerve endings in it and also is not a good bearing material, any motion between bones without cartilaginous surfaces causes significant pain. The mainstay of non-operative treatment is to control this process by decreasing the force applied across the joint, as well as decreasing the number of times that the force is applied. In addition, antiinflammatory medications will help control the symptoms. In order to decrease the force, several things can be done. The first is weight loss; any excess weight causes significant extra force across the joint which increases the joint destruction as well as pain. Because of the muscles acting across the knee joint, normal walking causes force across the knee approximately three to five times of the body weight. Therefore, if you are 20 pounds over weight, the force across the knee is increased by almost 100 pounds. Any effort at weight loss will decrease the force about the knee, slow down the destruction of the knee joint and decrease pain. Another way to decrease force is to use a cane or crutch. Usually, it is used in the opposite hand, but can be used in the hand of the same side as the involved knee. Avoidance of unnecessary activities such as jumping, jogging, impact loading or heavy lifting ( greater than 20 pounds) . In the 40-60 age group, patients with bowed legs or knock-knee deformity, an " osteotomy" of the knee may be the best operative procedure. This is where the upper end of the tibia bone near the knee is cut and a wedge of bone removed to straighten the leg. This procedure requires that some portion of the knee still have viable cartilage on it and is not possible when the cartilage is completely destroyed. This procedure has approximately a 70% success rate and success is defined here as improvement of symptoms rather than complete freedom of pain. It is however a conservative operation that preserves the knee joint and can allow future conversion to a total knee replacement. Another alternative is " arthroscopic debridment". This is when an arthroscope is inserted into the knee and various instruments are used to remove arthritic debris from the joint. Areas of full thickness loss of cartilage may be drilled or abraded. This procedure usually 3 gives temporary relief of approximately six months but occasionally can work for several years. If there is x-ray evidence of SEVERE arthritis, arthroscopic debridement is usually not advised. A final alternative is " partial knee replacement" ( uni-compartmental knee replacement). This may be applicable if only one compartment ( medial or lateral) is worn away and the remainder of the joint still has good cartilage. This is usually NOT recommended under age 50, when an osteotomy might be tried. In your particular case one of these alternatives may be applicable. This should be discussed with Dr. Endicott. BENEFITS OF THE PROCEDURE Total knee replacement is one of the most successful of all surgical orthopedic procedures. Total knee replacement initially got a bad name as compared to total hip replacement. Early designs did not take into account the complicated biomechanics of the knee joint. In the mid -1970's, an engineer by the name of Peter Walker designed a " semi-constrained" knee replacement called the " Total Condylar" knee. This design allowed stresses to be taken up by the ligaments and yet had enough constraint to provide stability. Use of these prostheses and various modifications such as preserving the posterior cruciate ligament and development of more accurate instrumentation has allowed the success rate to increase dramatically. At the present time, knee replacements are felt to succeed 95-98% of the time; these results are actually better than total hip replacement. A "success" is defined as freedom of pain and restoration of motion as well as function. A successful knee replacement will allow a person to return to the routine activities of daily living. Certain restrictions do apply however. Persons with total knee replacement should not expect to resume to jumping or jogging activities or any impact loading. Lifting of weights of greater than 50 pounds should be avoided. Singles tennis and racquetball are not advised but golf, 4 swimming, and bicycling are good exercises. There are also some restrictions of motion. Although the leg with a knee replacement can flex up to 120 degrees, it is not advised that you attempt to bend it more. An ideal candidate for total knee replacement is a patient who is over 65, relatively sedentary, with normal mental capacity, and who is not overweight. The converse of this represents the so called " high risk patient" for total knee replacement; namely those who are under 65, overweight, excessively active or who have had a previously cemented total knee that has failed. The relative success rates and risks in this group are discussed below. In summary, if you are an ideal candidate, the expected benefits from total knee replacement should be 95-98% chance of relieving all of your pain and restoring motion and function for routine activities of daily living. RISKS AND POSSIBLE COMPLICATIONS The two major complications that can cause failure of a total knee replacement are infection and loosening. Infections has a very small chance of occurring ( 1 out 100 in first time knee replacements, and 4 out of 100 for revision knee replacement), but if infection occurs, it is a very difficult problem to treat. Most infections in total knee replacement occur due to contamination at the time of surgery or subsequent wound breakdown. It is a myth that surgery can be a truly sterile procedure. Any time that people are in an operating room, there will be a small number of bacteria that can settle in the wound. We take many precautions to decrease the number to a minimum. These include the use of sterile instruments and drapes as well as gowns and masks and head covers. In addition to these routine procedures, the surgery is preformed in an " ultra clean room" or "laminar air flow room". In this type of operating room, a uniform flow 5 of filtered air is continually circulated over the wound. Another measure to decrease infection is the use of " prophylactic antibiotics". This means to use antibiotics in advance of surgery to prevent infection rather than treat it after it occurs. Prophylactic antibiotics are usually given within an hour of surgery and sometimes we use antibiotics during surgery and for 48-hours after surgery. If an infection occurs in a total knee, every effort is made to retain the prosthesis but less than 50% of the time is this successful. If the implant is loose or if the infection continues to recur, it is usually necessary to remove the implant completely in to order to cure the infection. This of course, leaves no knee joint and although walking is possible usually two crutches are required, the leg requires a brace and motion is minimal. At least six weeks of intravaneous antibiotics are required to treat the infection. After three weeks, consideration can be given to reimplantation of a total knee but statistics show that 20% of reimplantation cases develop infection again. Therefore, not frequently is the knee fused in a second procedure. The second major complication is that of loosening. The key success for a total knee replacement is that all motion should occur between inert materials( i.e. metal and plastic). If any movement occurs between the implants and their respective bones (i.e. loosening), this will cause pain, bone resorption and ultimate failure. Loosening usually takes several years to develop and can occur as late as 10 to 15 years for a cemented implant. The process of loosening is attributed to failure ( cracking) of the cement used to anchor the implant to the bone. It is felt that this cracking is a " fatigue failure" caused by multiple repetitive loads or loads that are excessively high in certain areas. This can also be caused by poor alignment of the implant. The risk of loosening in ideal candidates is approximately 1% - 3% in 10 to 15 years. In non-ideal candidates such as patients with excessive body weight and younger, more active patients as well as patients who have had a previously failed cemented implant, the chance of loosening increases. Revision total knee replacements require special mention. A revision is defined as a total knee replacement done for a previously failed 6 implant. The chances of success in revision knees is only 80% compared to 95% to 98% for primary procedures and this is for a very short term. Most of the causes for failure have been loosening. Infection is also increased up to approximately 4%. Other possible complications need to be mentioned. Instability can occur due to poor ligament balance. This can cause buckling when weight bearing and may require the use of a knee brace and/or cane. Usually it is not painful. Rarely is revision surgery needed to correct this problem. Instability is relatively rare with only 1-2% having a functional problem. Another complication that should be discussed is blood clots that can form in the legs or pelvis. In and of themselves, the blood clots are not a threat; they can be treated with blood thinners and will ultimately resolve. The big concern, however, is that a portion of the blood clot can break off and go to the lung " pulmonary embolus". If that occurs, it can be life threatening. Various preventative measures are used to decrease the risk of blood clots forming. You are normally given a blood thinner, which is usually coumadin, during your hospital stay and most times will continue even after you have been discharged home. This blood thinner helps prevent clot formation. Compression stockings and Continuous Passive Motion (CPM) machines are also used but early ambulation beginning on the first day after surgery and active bed exercises such as ankle "pumps" are most hopeful. There is additional information available on the internet if further research and information is desired to assist you in your decision. My office staff is also available to answer any further questions that you may have. The following is a link from the American Academy of Orthopaedic Surgeons: http://orthoinfo.aaos.org/topic.cfm?topic=A00389