None — Henry Finn, M.D., from the University of Chicago Bone and Joint Replacement Center at Weiss Memorial Hospital, explains a procedure to un-fuse knees.
When has knee and bone fusion been done? When is it used?
Dr. Finn: Knee fusion continues to be performed, but less frequently, partly because of the modern day limb salvage, and because of the development of newer and better implants and surgical techniques. Historically, it was done in situations where a knee was so badly damaged, either by trauma, tumor, deformity, severe arthritis or infection; and particularly infection after knee replacement, which is the case with Mr. Logan. In a young patient, it wasn't felt that a knee replacement would be durable enough. Therefore the two bones were surgically fused—like healing a fracture—as what was thought to be a permanent procedure, and with limited function and long-term durability.
What are some of the limitations of someone who has a knee fusion?
Dr. Finn: I have to tell you that I've interviewed hundreds of knee fusion patients. The first thing that they usually say is: I was never told what it was going to be like to live with a fused knee. I was just told that a fusion is what I needed, and it would solve my problem. They quickly find out that this makes activities of daily living nearly impossible. It makes it almost impossible to drive a car. It makes it nearly impossible to get in and out of a movie theater. You cannot bend or squat. It's kind of like an appendage that works as a peg leg and is there so you can ambulate, but pretty much for everything else it's always in the way. It also causes back pain, and almost always when a knee is fused, the leg is shorter, so people have to wear a shoe lift, and they may develop arthritis on the opposite side in their hip or knee because of the extra burden that the knee or hip on the other side are forced to take. These are the things that we see the patient complain of; and universally, every patient that I've met has told me that they've hated every day of their life that they lived with a fused knee.
Are there some cases where that's still the only option?
Dr. Finn: Yes, it is. At least, there are different thresholds for going on to continue with a moving knee reconstruction for different physicians. At some point, it becomes impractical to continue on risking a patient's leg with ongoing attempts to give them a moving knee. In the day and age that we live in today, I would estimate that the most common reason a fusion is done is inability to cure an infection following a total knee replacement in a younger patient.
Were the patients told that a knee fusion was permanent?
Dr. Finn: Not only were the patients told that, but it's taught as dogma that once fused, there's no going back. It's a bridge that's burned, and I've discovered by serendipity, taking care of a patient who wasn't quite fused, but was ankylosed, which means that they had just the jog of motion, and I was successfully able to restore their motion. It made me believe that this could be accomplished even with a great deal of risk in the fused situation.
How is the procedure done?
Dr. Finn: Technically it's very difficult, because most of these patients have had multiple procedures and the soft tissue envelope that surrounds the knee including skin, joint capsule, ligaments, tendons, nerves and arteries, have been altered anatomically. They're scarred, they're non-compliant, and it is extremely risky to open the knee. There may be multiple previous incisions that make it difficult to use one incision or the other for fear that you may cause gangrene of the skin between the two incisions. Everyone that you operate on is different; each surgery is unique. We carefully go in the knee on the side that we choose and lift the soft tissues and at a certain point we have to make a critical decision where we put a saw that is battery controlled and is strong enough to cut a wall down through the bone at the level we want to put the joint in. The saw must cut the fused bone, but not cut the major arteries and nerves that nourish and keep the leg alive and functional, and that's the critical moment where a limb could be lost. To decrease the chance of arterial injury, I always do a pre-operate arteriogram to look at the blood vessels as a map, and I also always have a vascular surgeon evaluate the patient and be on call should there be an injury to the major artery. So far, I have not had to use them, thank the Lord.
What should patients expect?
Dr. Finn: Unlike a lot of patient-doctor relationships where the patient comes, and the doctor says yes, we could take care of this, there's probably a 98 percent chance of a successful outcome. This is completely different. My approach is to first get a feeling about the patient's psyche, and to talk to them in detail about the risk and explain to them that this is a relationship that we're entering into together, it's not just about me fixing their knee. They have to comprehend their realistic potential for loss of limb, and they have to be willing to commit to an intensive rehabilitation program to make it worth it.
What does a patient need to get this procedure?
Dr. Finn: We always obtain informed consent and explain in detail their risks associated with this complicated procedure. I remember Mr. Logan; I spent an hour and a half on just the first visit with him and his wife, explaining what was involved and what the risks were, and then told him that he'd have to wait five years and think about this, for a number of reasons. One is he had a recent infection; two, he was very young; and three, I wanted him to be absolutely sure that he understood all of the risks; so I told him to come back to see me in five years, and he did. Patients look at things different than we do. We're now starting to learn this in our research endeavors, but the most common thing I hear is after a long discussion, they conclude well: At least if I attempt this surgery and it isn't successful and I lose my leg, I'll have a prosthesis where the artificial knee will bend. Now clearly, they would be better off with the fused knee, but their feeling of this loss of motion is so significant, that that's how they kind of look at it, which seems to be a universal remark that I hear. There is a saying in the orthopedic world, life is motion and motion is life, and when you lose that motion, you lose a lot of your life, and in Mr. Logan's case, for example, he couldn't enjoy his young children, which now he can.
How many of these have you done?
Dr. Finn: Approaching close to 50.
What is the success rate?
Dr. Finn: We've never lost a limb. We've had one infection, which can be devastating but was successfully treated, and the vast majority have had an excellent outcome and have been highly satisfied. The range of motion is above 90 degrees. It is necessary to have 90 degrees to successfully negotiate stairs foot over foot. 90 degrees is the ball park we're shooting for, but many of the patients get more. At three months, when I last saw Mr. Logan, he was already up to 110 degrees.
How long does the rehab process last?
Dr. Finn: The intense rehab is at least 3 months, but then there's ongoing rehab and improvement for up to a year for the most dedicated patients.
What would you tell a patient about this procedure?
Dr. Finn: This is not what we would call a national perspective standard of care procedure. If I were teaching a young resident or a young doctor who was considering this procedure, the standard response would be that the complication rate by others who have tried it is so high, as high as 50 percent, that it's not reasonable to consider. Now, with a great deal of caution, and creativity, we've been able to get the results to where I feel it's acceptable for the well informed patient. There's also a concern that we didn't talk about. The device that we use, which I developed, is not as durable as a conventional knee replacement. Now that we have data that shows the device lasting as long as 20 years, we feel a little bit more secure. The conventional hinges of the past may have failed in three to four years, starting off a whole new process of needing a revision, and the one thing that people always have to remember is that to insert this device, we have to remove bone, and once we put the knee in, you can't go back to a fusion, so that's why you could require an amputation.
What's the process like?
Dr. Finn: In terms of the hospital stay and the rehab process, everyone is variable, but the best case scenario is that they're hospitalized three to four days, and then they're off to their home, or a skilled nursing facility. People do travel long distances—from all over the United States—for this procedure, so those patients have to stay in Chicago for three weeks, and then return to their home and start intensive therapy there. But everyone is different. Some people may need skin graphing, some people may need muscle flaps, some people may need to be protected from their tendons that are weakened, so every case is individualized.
Is there anywhere else in the country where they're doing this?
Dr. Finn: Knee fusion disassembly has been attempted over the last 30 years at a number of locations. As I understand it, for the most part because of the high complication rate or the poor outcomes, I'm not aware of anyone that is doing it in the United States as we speak today.