David P. Adkison, MD, St. Vincent's Orthopedics, PC
Knee Replacement FAQs: Knee Replacement
Will there be much pain after surgery?
There’s simply no way around it — yes, there will be pain. However, we go out of our way to minimize the amount of pain you experience, including using cell technology to minimize the inflammatory response. We have very flexible standing orders allowing your pain medication to be adjusted as needed. There is also a pain nurse who is quite good at helping us individualize pain medication needs. I’m a firm DISbeliever in the "no pain, no gain" theory of medicine practice.
Can you straighten my leg?
Absolutely. We use intermedullary guides to help align the components of the knee arthroplasty. In fact, one of the great advantages to a complete knee replacement is a superior ability to straighten the leg. Our goal is to allow you to gain full extension — to lock your leg out straight and also straighten it if you’re bow-legged or knock-kneed.
What are the dangers of the surgery?
The foremost risk is of a blood clot forming in the leg, dislodging and going to the lung. We’re extremely aware of this possibility and use blood thinners to prevent this complication. The second most common danger is of an infection. My infection rate is currently well below 1%. The national average is 1 - 2%. Additional dangers such as fracture and stiffness are much less common.
Will I be able to run or play tennis again?
The answer for run is NO. Running is uniquely bad for joint replacements. You should run ONLY to save your life or to catch a bus. The answer to tennis is yes — IF you play doubles on a soft court. Singles on a soft court is controversial but I allow it depending on how the person’s function regains. When God engineered the knee, He built it with a lot of cushion and rebound. Even though our technology and technique for replacing a knee is quite good, our abilities are just not in the same league with the Lord.
How much does the artificial joint weigh?
10 ounces. There is almost an even swap in the weight of bone and scar tissue removed and the knee replacement components.
How big an incision will I have?
The incision we use is between 4 - 5 inches. Occasionally it is longer depending on how large the knee is.
How long will the artificial joint last?
The components we use have a life of 15 to 20 years for 90% of people. The longevity of the joint is related to a number of things including the patient’s activity level (a joint will not last as long for those who run against orders). People who develop a very stiff knee sometimes will have to have at least the plastic part changed out in order to regain their motion. But this is extremely uncommon in our practice.
When will my pain go completely away?
This varies so much with an individual that it is hard to say exactly. Some patients’ pain is completely gone in three months while others may take as long as nine months. How quickly your pain goes away completely is a function of your knee nerve supply and how much scarring you develop.
What is the joint made of?
The thigh bone component is made of cobalt chrome which is highly polished and very pure. The tray that sits into the shin bone is made of titanium and there is a high molecular weight polyethylene plastic that sits in between those two as your cushion. The back of the kneecap is also polyethylene.
Have you used any joints that have been recalled?
No. Occasionally, medical reps try to convince us to change joints but I haven’t found anything better than what we are currently using. Using the analogy of how someone decides what kind of automobile to purchase — I like to think of our knee replacement components as an F - 100 pickup truck. It works day in and day out and lasts a long time.
Do I need to donate my own blood?
Overwhelmingly, the answer to that is NO. Not using drains and taking care of all bleeding at the time of surgery, has kept our blood transfusion rate down to less than 2%. What we typically find is that people who donate blood have to donate it within three weeks of surgery. They show up for surgery with a low blood count and we have to give them their blood back because their blood count is low. Donating your own blood just doesn’t make a lot of sense to me.
How does the joint stay in place?
The thigh bone component is press fit into place with a very precise cut. The shin bone component is either cemented or press fit to the polyethylene in between the two is snapped into place in the tray of the shin bone component. The kneecap portion is cemented into place. These are also held into place by ligaments that we leave completely intact to keep the joint space stable. It may be of some interest for you to know that the man who figured out this design rationale back in 1978 was knighted by Queen Elizabeth for his work.
Will I be able to climb stairs again? Can I squat or kneel?
The answer is YES. The ability to climb stairs again occurs when you have 110 degrees of knee flexion. Squatting requires about 145 degrees of knee flexion. Kneeling is OK as long as you don’t kneel on the kneecap but on the upper part of the shin bone. Our measurements for flexion, by the way, are that with your leg locked out straight (for most people that’s 0 degrees) and if you’re sitting with your knee bent while sitting in a chair and it’s a right angle, that’s 90 degrees. So you can see that you need a little bit more than that amount to climb stairs. You might be reassured to know that we work very hard in surgery to maximize the amount of flexion the knee gains. We place the back of your foot against the back of your thigh by the time we’re done. Of course, you’re asleep when that happens. When you awake you won’t be able to get that kind of flexion immediately, of course, but with time, that goal is very attainable.
What are my chances of developing adhesions or scar tissue?
Scar tissue forms in everybody but varies greatly from person to person. Some people form keloid (overgrown scar tissue) and they have an extremely difficult time. We’ve had to break up adhesions in only about 15 people in the last 1000 knee replacements. Scar tissue’s effect on you depends on how many nerve fibers are in your knee and how you respond to pain.
Do you use the passive motion machine?
Yes.
Do you ever replace both knees at the same time?
I have replaced both knees at the same time but I prefer not to because I think it is important that you have "a good leg to stand on". Furthermore, in doing both knees at the same time, there is an increased risk of developing a dangerous blood clot. There is less danger of blood clot if the knees are done at least 3 months apart.
How long does the actual operation take?
The operation takes me about an hour to an hour and fifteen minutes, depending on the amount of scarring I encounter and the amount of tissue adjustment that has to be done during surgery.
Will my skin be numb after surgery?
For some time, yes, in most people. The nerves to the outside of the knee come from the inside of the knee along the saphenous nerve. So it would probably be wise for you to expect some numbness but most people have recovery, although some might never recover the sensation to the outside of the kneecap.
What type of anesthesia will I have?
That depends a lot on whether you have arthritis in your spine, whether you have heart problems and whether you’re uncomfortable being slightly awake during surgery. There also is a benefit to using an epidural which is a catheter placed in the back through a needle. After it is placed, medicine can be infused around the spinal cord on a continuous basis. Folks who have this done are comfortable in the first 1 - 2 days after surgery but then have some discomfort known as rebound when the catheter is removed. Blood thinner control is also difficult when the epidural is in place. If I were having my knee replaced, I would go to sleep and put up with the pain during the first day and take the blood thinner.
Will I have to take blood thinners?
YES. See the above question and question # 3. The complication that concerns me the most after knee replacement is a blood clot from the leg that might break loose and go to the lungs and so we’re very aware of this problem and use Coumadin for the most part. Blood thinners have to be taken only for about 10 days unless there are other complications or other health problems such as atrial fibrillation which requires chronic Coumadin therapy.
Birmingham, Alabama 