Total Knee Replacement Surgery

 

What is a total knee replacement?

Total knee replacement is the replacement of the entire knee with a metal surface replacement and a plastic insert. During a total knee replacement, all three compartments – the medial, lateral and patellofemoral compartment – are replaced. Components are usually fixed with cement. Most modern knee replacements are relatively bone preserving and just remove the superficial layer of cartilage and bone and replace it with a metal-on-plastic implant. Today we differentiate between posterior cruciate ligament preserving, so-called cruciate retaining and posterior cruciate ligament sacrificing, so-called posterior stabilized knee replacement. While posterior cruciate-retaining knees are often more bone preserving, they in general provide not the same function. In particular, posterior stabilized knees achieve a larger arc of motion than cruciate-retaining knee replacements. While there is some controversy on whether the kneecap needs to be replaced in all instances, we usually prefer replacement of the kneecap in all patients since it is in our hands the more predictable way to alleviate and avoid anterior knee pain after total knee replacement.

When am I a candidate for total knee replacement?

Prior to indicating total knee replacements, all patients should have non-operative treatment first. Total knee replacement is not a benign procedure and does have medical and surgical risks and therefore non-operative treatment should be considered first before moving on with replacement surgery. Non-operative treatment in general consists of anti-inflammatories to relieve pain and swelling, cortisone injections into the knee, lubricant injections, the use of braces, the use of physical therapy, and activity modification. Especially cortisone injections are often very helpful since they will often result in complete relief of symptoms for up to six months. Braces can also be very helpful especially if the arthritis only affects one side of the knee since they can help shift the load to the unaffected side and by doing so decrease the pain associated with arthritis. Lubricant injections often receive a lot of media attention; however, patients do not respond to them as predictably as they do to cortisone injections and very often this costly treatment option is not indicated because there is too much arthritis. Activity modification and weight loss are very simple ways to decrease load on the knee. If you imagine that the knee will see up to eight times your body weight during certain exercises, it becomes clear how helpful it can be to drop even a few pounds to decrease the load on the arthritic knee. There is also little question that obesity is the driving force behind knee arthritis. So if you want to prophylactically decrease your chance of developing arthritis, keeping your weight within the recommended range can be extremely helpful. Activity modification is another option to decrease your pain related to arthritis, especially when we talk about recreational activities. The quote “if you have pain with running then do not run” does hold true for arthritis. This is primarily true for activities one can not do after a total knee replacement, like running, playing basketball or rock climbing. Now I guess everybody understands the limitation of that. There are certain activities that are just essential to live a fulfilled life and once the arthritis affects those activities and using other non-operative modalities does not provide with an adequate amount of pain relief, then we will often discuss the option of knee replacement surgery.

What does it entail to have a total knee replacement surgery?

Well usually after you undergo medical clearance you are admitted to the hospital the day of your surgery. You will then undergo a spinal epidural anesthesia, a regional anesthesia that allows us to control your pain during surgery and after surgery and has less risks than general anesthesia. The surgery itself takes about an hour to an hour and 15 minutes and after the surgery you initially will be transferred to a postoperative recovery room where your vital signs and the weaning of the anesthesia is monitored by an anesthesiologist. You are then transferred to the floor where the day after surgery physical therapy and rehabilitation will start. Usually within two to three days you are able to leave the hospital. Dr. Boettner in general recommends that you go home after surgery where he will provide you with a CPM machine and a therapist that will check on you during the week to make sure that you achieve adequate physical therapy. By the time you leave the hospital, your knees should achieve at least 90 degrees of range of motion, you should be able to walk 100 feet with either a cane or walker and you should be able to walk a flight of stairs. By the time of discharge, your incision should be dry.

What is my activity level when I get home?

By the time you go home you should be able to move around in your apartment and house and take care of yourself. We do close incisions with resorbable stitches covered by surgical glue and therefore you should be able to shower right after you get home. During the day, you will be required to work for six hours on a bending machine to increase the range of motion of your knee. Dr. Boettner also recommends that you do not walk outside the house the first three weeks until the swelling in the knee is reduced and you have achieved normal range of motion. During your early postoperative time, you will take narcotic pain medication to control pain. Once you achieve good range of motion and the swelling of the knee is reduced, we usually recommend to taper down your narcotic medications by three weeks after the surgery.

Is it dangerous to undergo total knee replacement surgery?

Now a total knee replacement is not a completely benign procedure and very occasionally a patient can die from this surgery. However, by providing medical clearance in advance to your surgery, by making sure your heart and lungs are healthy enough to undergo the surgery, the capital risks of total knee replacement have been significantly reduced, and today most patients will undergo the surgery without any complications and will achieve a well-functioning knee. Risks of the surgery include surgical risks like intraoperative risks of fracture or damage to ligaments as well as risks to damaged neurovascular structures around the knee. There are also postoperative risks which include the risk of infection. We therefore recommend to use antibiotics whenever you see a dentist or have other invasive procedures after you have a knee replacement surgery. There is also a risk that your knee could be stiff or unstable after surgery. While instability after surgery is usually related to how the surgery is done, stiffness is affected by both the surgical technique as well as your willingness and motivation to work on your range of motion after surgery. There is also a risk that your knee could be malaligned after the surgery or that the wrong size knee is chosen at the time of surgery. Picking a surgeon with experience as well as an institution that specializes in knee replacement surgery can minimize a lot of the intraoperative risks with total knee replacement surgery. Besides the other risks of knee replacement surgery include the risks of blood clots as well as serious complication like pulmonary emboli, heart attack or stroke or bleeding complications from blood thinners. We put all of our patients on postoperative pneumatic compression devices to increase the blood flow in the lower extremities and we will also in general use Coumadin to prevent blood clots. There is also a small risk of nerve damage. Now why Dr. Boettner has never encountered lasting nerve lesion after total knee replacement surgery, the risk of nerve damage does exist and it is especially increased in patients that have very stiff knees and knock-knees. Please discuss your individual risk for surgical complications or nerve injuries with Dr. Boettner during your preoperative appointment.

What type of implant will be used?

Dr. Boettner uses different types of implants. Primarily we work with the Legion primary knee replacement from Smith & Nephew as well as with the Ortho Development Balanced Knee system that was designed by Dr. Boettner. Please ask Dr. Boettner if you have specific questions of what type of knee replacement will be used in your individual case. All total knees implanted by Dr. Boettner are posterior stabilizing knee replacement designs since they do allow for better deformity correction and better postoperative range of motion.

What are common problems encountered that I need to know about when I undergo knee replacement?

Now we perform knee replacement surgeries in order to relieve pain and restore range of motion and make you able to walk and enjoy your life. Having said this, some patients will experience clicking in their knee which is related to the common post mechanism of the posterior stabilized knee replacement and is absolutely normal. Often the amount of clicking will decrease over time. Having clicking is not a sign of malfunction of your knee replacement. Another common symptom after knee replacement surgery is numbness on the side of the incision. Since small skin nerves cross the incision, it is very likely that after surgery you will have a numb spot on the outside of your incision. This usually decreases in size over time; however, sometimes this numbness will persist. This type of numbness has no impact on your ability to use your knee and live an active life.

Stiffness.

Now, as a surgeon we usually look at range of motion and most of our patients will receive excellent range of motion. However, during the early postoperative time period you might feel that your knee is stiff even if its measured range of motion is where we want it to be. Complete restoration of a normal feeling knee can take up to a year and sometimes patients will continue to have some slight stiffness even years after the surgery.

Should I wait as long as possible to have my knee replacement surgery?

Now a common misconception about knee replacement is that one should wait as long as possible. Dr. Boettner recommends regular followup visits every 6 to 12 months if you are a patient with bone-on-bone arthritis in order to monitor the degree of deformity, the amount of bone loss from the arthritis and the degree of stiffness. Now in general you can live with an arthritic knee until you feel that you no longer can handle the pain and functional disability associated with the arthritic knee; however, if your knee gets very stiff, if the deformity exceeds 15 or 20 degrees of mechanical malalignment or if you develop progressive bone loss, Dr. Boettner might recommend to proceed with knee replacement surgery earlier. Especially patients with very stiff knees should consider undergoing surgery sooner rather than later because preoperative stiffness is a very important predictor for postoperative range of motion and waiting until the last minute with a very stiff knee can have significant impact on your functional outcome after surgery. Please discuss this with Dr. Boettner to make sure that continuing non-operative treatment is the appropriate way to handle your arthritic knee.

One last word.

Total knee replacements have not the best reputation and some patients are concerned about the pain that can go along with having the procedure and are worried not to achieve the desired activity level after the surgery. Dr. Boettner specializes in knee replacement; our surgical technique and perioperative pain management are aimed at keeping you comfortable throughout the recovery. We utilize minimal invasive surgical techniques, apply medications to minimize blood loss, use pain medications already before the surgery to make sure you do not experience severe pain and use an intraoperative cocktail injected into the knee tissues to minimize postoperative pain. Not doing the surgery when it is indicated is not a smart alternative. Lets discuss your concerns and I am sure you will feel that you can trust us with your care.