TOTAL KNEE REPLACEMENT WITH ZIMMER GENDER KNEE PENNSYLVANIA HOSPITAL PHILADELPHIA PENNSYLVANIA

Transcription

1 TOTAL KNEE REPLACEMENT WITH ZIMMER GENDER KNEE PENNSYLVANIA HOSPITAL PHILADELPHIA PENNSYLVANIA September 14, :00:10 Announcer: Until recently, knee-replacement surgery has relied on prostheses of varying sizes to account for anatomical differences between men and women. 00:00:19 DR. ROBERT E. BOOTH, JR.: I think this is a new concept. It s real. It s anatomically based. It s been staring at us for a couple decades. We ve all seen it and talked about it, but now we re actually going to do something about it. And I think with Simmer s help, this is going to be the advance of this decade. 00:00:36 Announcer: Now a new procedure takes into consideration these differences. During this life webcast, Dr. Robert Booth, Jr., chief of orthopedic surgery at Pennsylvania Hospital in Philadelphia, Pennsylvania, will perform a total knee replacement procedure featuring the Zimmer Gender Solutions high-flex knee, the first kneereplacement shape to fit a woman s anatomy. At any time throughout this program, you may questions to the physicians by clicking the MDirectAccess button on the screen. 00:01:08 DR. GILES SCUDERI.: Hello, everyone, and welcome to Pennsylvania Hospital in Philadelphia, Pennsylvania, where Zimmer s proud to broadcast a live total-knee procedure featuring the Zimmer Gender Solutions high-flex knee, the first kneereplacement shape to fit a woman s distinctive anatomy. I m Dr. Gil Scuderi from New York at the ISK institute and Dr. Robert Booth will be performing the surgery. Knee replacements have long been available in many sizes, but merely using a different size for women doesn t resolve anatomical differences. Various studies show that women s knees significantly differ in their shape from men s knees. Pioneering research conducted for Zimmer precisely maps out those differences and is the foundation for the design and the development for the Gender Solutions knee. When placing traditional implants, some surgeons accommodate women s differences by removing more bone or repositioning the implant during surgery, but their ability to make the implant precisely conform to the patient is limited. The Gender Solutions high-flex implant was designed so that the surgeon can more precisely match the female patients knee anatomy. I d like to remind the audience that you can submit questions to the surgeons here by your during the broadcast. Simply click the button on your screen. At this point, I d like to introduce Dr. Robert Booth and his staff. Dr. Booth will now introduce us to the staff and show us the case. Dr. Booth? 00:02:39 DR. ROBERT E. BOOTH, JR.: Thank you, Gil, and thank you very much for coming down from New York to moderate and help with this presentation. My staff here, who also I thank for coming this evening, starts with our scrub nurse, Leslie Wright. My first assistant is Michelle Anderson, whose a physician s assistant, as well as Marissa Marsicano. Our anesthesia tech is Carol Pesic, who s a CRNA, and then there s Jane

2 Collins, who s our circulating nurse. And last, our sales representative from Zimmer is Tom Miller. So this is the team who were gracious enough to come tonight and with whom I m happy to work every week. Our patient is a 57-year-old female. She s 5 6, 147 pounds. She has two arthritic knees. She has a lot of difficulty with stairs and chairs because as with many women, a great proportion with her arthritis is in the front of her knee underneath her kneecap. The main part of her knee is mildly arthritic, but underneath the kneecap, it s very arthritic, and I think you can see on these X-rays that there s no space left there. You ll see that when we open her knee and take a look at it. She s typical of many patients in that she s of an age where she s still very active, is athletic, social, married, runs her own company, and has knees now which are compromising her lifestyle. Her pain tolerance is very good. She s put up with this for a long time and tried practically every known conservative measure, including medications, injections, physical therapy, and even visco supplementation, but now she s reached the point where her life function s limited, her pain is persistent and annoying, and she s anxious for a solution to her discomfort. So we re going to do a total kee on her and share that with you tonight. All right, we ll get started here. 00:04:37 DR. GILES SCUDERI: Bob, do you have a tourniquet on this case? 00:04:39 DR. ROBERT E. BOOTH, JR.: Yes, we do. We do all our knees, as much as possible, under tourniquet. Obviously, not 100% of them can be done that way for a variety of medical reasons, but whenever possible, that gives us pretty much a bloodless field. It also speeds up the surgery a good bit. 00:04:54 DR. GILES SCUDERI: I see you like to make the incision with the knee in a flex position. Does that matter? 00:04:59 DR. ROBERT E. BOOTH, JR.: Well, I ve started doing that recently, Gil. All surgeons I think every surgeon in America is trying to make slightly smaller incisions than they made a few years ago. Part of it is for cosmesis, but the important part is the less damage you do to the tissues, the less discomfort and theoretically, the faster recuperation. So this is a modified minimally invasive knee. 00:05:22 DR. GILES SCUDERI: Personally, I found the incision is a little bit longer in flexion than extension. When you bring the knee out straight, the incision actually looks a lot shorter. 00:05:28 DR. ROBERT E. BOOTH, JR.: Right, I learned this from you, actually. You taught me this. 00:05:32 DR. GILES SCUDERI: Well, thanks, I appreciate that. And I see you re doing a what you call a quad-saving type of approach to the knee. 00:05:41 DR. ROBERT E. BOOTH, JR.: Well, years ago, as you know, the incisions would be a foot long or longer, and we would go way up into the thigh and into the tendon that is part of the quadriceps muscle, and I think all of us have learned how to avoid that now so that our patients have less pain and also are up and moving right away. Pain s a big part of this, and this patient has received Oxycontin, which is a narcotic, just before surgery. She s taken a Celibrex, which is an anti-inflammatory drug. So she s already on the path to avoid pain. Carol Pesic has an epidural anesthetic in her right now, which is how we re going to manage her pain not only for this surgery, but

3 it s actually going to stay in for a couple days afterward. So we can get her up and standing and walking painlessly tomorrow morning. 00:06:27 DR. GILES SCUDERI: You know, I ve found this type of exposure is still very extensile. Even though it s limited, you do get a very good exposure to the knee joint. 00:06:35 DR. ROBERT E. BOOTH, JR.: I think one advantage this evening is that we ll be able to see pretty much everything in this case with our good photography crew here because we have the ability to see almost the entire knee at any moment. 00:06:46 DR. GILES SCUDERI: Now, Bob, you do remove some of that synovial tissue and fat from the anterior cortex on the femur. Is that for visualization? And how much do you usually remove? 00:06:54 DR. ROBERT E. BOOTH, JR.: As you see, I took away a little bit up front there because the instruments there are several different instrument systems to do knees. I use one that s based on the bone in the front of the knee. And so I need to be down on the bone there to guide my instruments. Some people use instruments that go up inside the bone, but one of the concerns there is it can force marrow or fat or other products into your lungs. So one advantage of this approach is that it avoids that. 00:07:20 DR. GILES SCUDERI: So you avoid violating the canal. 00:07:23 DR. ROBERT E. BOOTH, JR.: If I can, yeah. 00:07:24 DR. GILES SCUDERI: Now, I noticed on the pre-operative x-ray, she does not have much of a deformity. So you re not going to do much of a soft-tissue release. 00:07:31 DR. ROBERT E. BOOTH, JR.: No, but what s interesting in looking at this knee is that, as I said before, most of her arthritis is anterior. This is bare bone showing through. Her patella is actually ground down not only through the cartilage but the bone beneath. She s actually ground away the bone. Her knee and if you look at enough knees you and I as knee surgeons see this, and I think perhaps even the people viewing can as well is sort of trapezoidal. It s not as boxy and square as a male knee, and that s one of the most important issues. I think the other thing you see here is the space between the bones, between the sides of the femur, is vary narrow. This is, again, a significant different in women. Most people know that anterior cruciate ligament injuries are five to seven times more common in women than men, and it s blamed on their soft tissues, on their quadracep strength, on the alignment of their lives, but one of the factors appears to be the narrowness of the bone here where they pinch or stress that ligament, and that may be why an ACL injury is properly considered a woman s disease in many ways. But that plays out when you re a joint surgeon as well. 00:08:38 DR. GILES SCUDERI: You know, this is a very typical-appearing female knee. It s very tall versus being wide. You know, as you said, the trapezoidal appearance. You can se the height of this knee. 00:08:49 DR. ROBERT E. BOOTH, JR.: And this is something that others a lot of people have talked about, you know, for 20 years. It s just we re now finally we ve solved the other problems of knee surgery. Now or most of them. Now we re able to deal with

4 more subtle problems, such as this. So what we re doing is taking away some of the bone spurs that have closed in this notch, and we re going to take out what s left of her accruciate ligaments. The anterior accruciate ligament is pretty well gone. It s frayed and worn over the years, and I think one of your partners, Norm Scott, did a study once showing that the majority of people whose knees are bad enough to need a knee-replacement have frayed or worn their anterior cruciate ligament. 00:09:27 DR. GILES SCUDERI: You know, many patients ask me, Doctor, you re removing the ligaments from my knee. How are you going to substitute for them? How are you going to replace them? And it s pretty much the implant design that does that, isn t that correct? 00:09:38 DR. ROBERT E. BOOTH, JR.: There are two schools of thought on this. One is to save the posterior cruciate ligament. That is one of the more popular schools but not the predominant one. And the difficulty with that is that the knee design is more complicated. I think it s harder for the surgeons to do, and the track record over the years hasn t been quite as good as this sort of knee. Our approach is to substitute for that ligament using a plastic piece, which you ll see later, and that s certainly easier, gives a little better range of motion and, we think, a better long-term result. So we ve chosen philosophy. 00:10:13 DR. GILES SCUDERI: So there are specific implant designs, the posterior cruciate substituting versus the cruciate retaining prosthesis, and that really depends upon the surgeon s preference. But you and I both prefer a posterior stabilized knee because we think it has better kinematics. 00:10:28 DR. ROBERT E. BOOTH, JR.: Yes, and I think we both learned that from the same fellow, John Insole, who was sort of the father of modern knee surgery. Just as John Charnley was the father of hip surgery, John Insole was really the person who set us on this generation of knees which have been so successful. And he was the first one to identify this female problem that I know of. 15 years ago, he saw the dilemma of having to cut away more bone in a female knee than a male knee, and he actually had extra parts made, a series of parts, that were a little taller than they were wide for the same width. And that s the only person I know who did anything about this 15 years ago. So he truly was the first in that as well. 00:11:11 DR. GILES SCUDERI: You know, John was such an innovator in total knee design, and we ve learned quite a bit from him both on surgical technique, and it s amazing how even today, we refer back to John Insole s implant designs. So, Bob, right now, you cut the tibia. You cut the tibia first in all your cases? 00:11:29 DR. ROBERT E. BOOTH, JR.: I do, and again, a lot of this is the way I ve done it for most of my career. This is the most predictable cut since it s only one surface. Getting this right gives me a base against which I can balance my other cuts. So if I get this cut square, which I think I have, this is the background on which the rest of the operation will be built. We then test the knee for size. We have a whole variety of parts. Again, something unique about women s knees is that they re a little narrower front to back than men s. They re a little more elliptical. If you can see the top of this knee, it s not as square as a male knee. So these components, Zimmer already has these tibial surfaces that are the same width, and then another, which is an evennumbered one, which is a little thicker. But by and large, the women use the odd numbered parts because their knees are a little narrower front to back. So we now know that size 3 is going to fit fine.

5 00:12:25 DR. GILES SCUDERI: Bob, you know, we re live, and we ve got a question here from the audience, and there s a question: How do you prevent cutting any arteries in the leg? I mean, we just showed the knee dislocated. How do you prevent cutting that artery back there? 00:12:39 DR. ROBERT E. BOOTH, JR.: Well, they re way in the back, first of all, and when you flex the knee, they re even farther back. Secondly, Marissa was using a retractor there not only to force the knee forward but also to protect from my saw going back farther. And of course, that s why these procedures are done by surgeons and not by robots still. I think that s our job security to be sure we do this right. So what we re going to do now AP measuring guide is check for the size of this femur. We ve talked about it, but these femurs let me have a big rongeur first, big rongeur come in different seven or eight different sizes. Obviously, there are a huge variety in range of people. So for years, we ve been forced to make the people fit the parts. One of the advantages of this gender knee is that it takes us a step farther towards having parts that are shaped to fit the people. So the next thing I m going to do is determine what size will fit on the front here. It looks about an E. Sometimes we re in between sizes and we have to make judgments. And the dilemma we ve had for years was that if we put on part that was big enough to fit the female femur front to back, it would often overhang, as we ll see later. And so that s what so special about this measurement. Getting this front-to-back measurement correct is more important than the side-to-side measurement because this is what determines the shape of the knee and thus drives its motion and makes it bend and function properly. 00:14:05 DR. GILES SCUDERI: That leads into a question here in the audience. He asks: Is the Zimmer fit for all women or are some women better candidates for the male knee device due to different anatomy differences? 00:14:16 DR. ROBERT E. BOOTH, JR.: Well, about 65, 70% of the women, I think, are candidates for this knee, but not just on the issue of shape. The particular reason in this lady is that there s very little bone up front, and also, that s where her arthritis is. So if we had parts that fit her perfectly, merely to put parts back on that duplicated what was there is really duplicating the same problem that got her here in the first place. So one of the things we can do as surgeons now is customize our knees. We can look at every knee and say, What went wrong with this knee? Can I, in doing my knee replacement, minimize the chance that the same thing will happen again? So, although the shape is important, the fact that this new prosthesis is thinner up front and has an angle that s more consistent with the angle of the woman s leg allows me to deal with what is really her problem, which is patella femoral arthritis. 00:15:09 DR. GILES SCUDERI: Bob, you mentioned something that I tell all my patients, too. I think with the Gender Solutions, I can intraoperatively customize their knee. I can find an implant that s of the right shape and size for whatever anatomy I encounter. 00:15:24 DR. ROBERT E. BOOTH, JR.: Yes, and that s what comes of years of looking at knees, as you and I have. I think it s not enough just to do it by the numbers anymore and put it in you know, in a routine fashion in every patient. So now we re going to take away bone in the front and the back to make to make space for these parts. 00:15:51

6 DR. GILES SCUDERI: So at this point, you re resecting the bone to accommodate the implant from the femur. 00:16:03 DR. ROBERT E. BOOTH, JR.: And I m trying to do it without getting my head in the way here. I hope you can all see this. All right. And again, this is a narrow one. 00:16:18 DR. GILES SCUDERI: How much bone do you actually remove? 00:16:20 DR. ROBERT E. BOOTH, JR.: Well, we don t measure it precisely, but it s probably around 7 or 8 millimeters in the front and the back. In the front, there s very little here, and you can see what we re trying to do is we re trying to create a rectangular space. The lines that s I ve drawn here the lines that I ve drawn here represent the axis of the knee about which it rotates. So if I can get this cut parallel to that and parallel to the axis of the knee, then I know that this knee is going to function properly and move well. 00:16:51 DR. GILES SCUDERI: Yeah, it looks like you used the epicondylar axis, which we discussed many, many times in the past, as well as the AP axis. And you find that s the functional axis of the knee. 00:17:01 DR. ROBERT E. BOOTH, JR.: Well, again, John Insole, your former partner, was the first to really deal with this. I don t think he ever verbalized it as much as he sort of intuited it. And his approach to knees was what made this so successful, because although most of the fame goes for the parts and the systems, it s really the philosophy and the technique that I think made him particularly special. You know, we do things a little differently in female knees, too. Women s are looser-jointed than men. So we want to be sure that this lady has extra motion because she s lean, and she expects to get better motion than an average knee, not what she had when she was a teenager, but certainly more than just able to go up and down stairs and to get out of a chair. She has much higher aspirations than that. So you yourself were the champion of the high-flex knee, which is incorporated in this design. 00:17:53 DR. GILES SCUDERI: You know, that brings up a question from Vicky in the audience, and she asks: Will the patients be able to bend their knee more using the Zimmer method versus the traditional method? 00:18:01 DR. ROBERT E. BOOTH, JR.: Well, these high-flex knees are made to accommodate just that very need. I mean, I think you can speak to this better than I, frankly. 00:18:08 DR. GILES SCUDERI: Yeah, what I d like to say to Vicky is that we ve found with the Zimmer high-flex knee, we ve been able to restore a high-degree of flexion, and it was specifically designed for patients who had high-flexion pre-operatively, and it is designed for safe flexion up to 155 degrees. So we ve really taken into consideration the patient s pre-operative motion, their functional activities, and their daily requirements. 00:18:33 DR. ROBERT E. BOOTH, JR.: I think that s exactly what the right advice is, I think. I think people need to realize, however, this is a partnership, and we can put in parts that will create and accommodate that motion, but they have to do their therapy and actually get that motion. 00:18:47 DR. GILES SCUDERI: Yeah, I think the patients are just as important as the surgeons sometimes with the functional outcome. It s how well you work, how hard you work

7 with your rehab. And That brings up a question from Angela in the audience. Angela asks: Do the patients need to go to rehab? And how long do they go to rehab? What do you do for your patients, Bob? 00:19:05 DR. ROBERT E. BOOTH, JR.: Well, everybody needs rehab of some sort, whether it s at home with someone coming to you, or whether you go to an out-patient rehab center, or whether you actually go and stay at an acute-care rehab center depends on your insurance, whether you re having one knee done or two, and other, often medical problems. If you have Parkinson s or other diseases, then clearly, rehab is a big asset. So we try and get as many I believe strongly in the post-operative acute-care rehab centers, and we try to get as many people to go to them as possible. 00:19:38 DR. GILES SCUDERI: I noticed in this particular knee I think primarily due to the fact that you had patellar femoral arthritis -- is that you resected very little bone from that anterior cortex of the femur. 00:19:49 DR. ROBERT E. BOOTH, JR.: And that s the problem. One of the problems is that if I put on the standard knee, I m going to be putting back more metal than I took away bone. And so that s going to create a problem called overstuffing, where we re putting more in than we took away. And that limits motion and creates discomfort. So particularly in women, that s a big issue. It s interesting, many women just don t like their knees. If you talk to them, and they said, I ve had trouble with my knees since I was a teenager, they and you don t hear that from men very often. It s usually the women who express that if you ask them. So now we re putting on a metal trial, or provisional, as it s called, and this is the standard knee. This is the kind we put in all the time, and if I can show you, this knee fits very well front to back.we ve measured it. It s just the right size. It ll preserve the anatomy and preserve the function of that knee. However, there s one problem -- which I hope you can see from the side here is that it overhangs a little bit. Not a lot, just a few millimeters, but enough that that s going to rub on the soft tissues. So my choice as a surgeon for years has been either to accept that little bit of overhang there can we turn it over even more? 00:21:00 DR. GILES SCUDERI: See, I think that overhang does cause soft-tissue irritation. I mean, some of the patients do complain of pain, and there s a particular tendon on the side, the popliteus tendon, that could snap or impinge, especially on that lateral side. 00:21:13 DR. ROBERT E. BOOTH, JR.: So my choice is either to accept this and have to deal with some discomfort, or I have the other option of I could put a smaller prosthesis on, but to do that, I d have to take away bone either bone in the front, which risks making the leg vulnerable to a fracture, or take away bone in the back, which makes it smaller than it should be and weakens the cam mechanism that makes the knee work, and that would cost me motion and function. So here before, I ve had to make a choice of one of those two options. The New Gender knee means I won t have to do that. We ll show that in a minute. So what we do now is put in what we call a floating trial because I know where the bones want the knee to work, but I want to now see how the knee itself would like to move, how it would like these parts to be positioned. 00:22:02 DR. GILES SCUDERI: And you re doing that specifically to see how the kneecap tracks.

8 00:22:06 DR. ROBERT E. BOOTH, JR.: Correct, because the tracking of the kneecap is a crucial part of getting this knee to function. Little bit on my side. And so I m going to mark where this knee would like the parts to sit as determined by the tracking of the kneecap. 00:22:22 DR. GILES SCUDERI: So in the past, you would have downsized this knee, wouldn t you have, Bob? 00:22:25 DR. ROBERT E. BOOTH, JR.: Yes. In my early years, I didn t have the option of that. Then when we learned to downsize, we either took the bone off the front, which you can t do here, because there is no extra bone there, or off the back, which changed the way the knee worked. 00:22:38 DR. GILES SCUDERI: And that could potentially lead to instability in some cases. 00:22:41 DR. ROBERT E. BOOTH, JR.: Yes. Precisely right. And that s independent of whichever style of knee of you use, whether it s cruciate retaining or cruciate substituting, as you talked about before, that choice harms both designs. 00:22:57 DR. GILES SCUDERI: Now, you re preparing the tibia, or the shin bone, for the final component. 00:23:01 DR. ROBERT E. BOOTH, JR.: Right, and this component has a little stem on it that will sit down inside the marrow cavity of the bone, and when I pop the knee back together again, you ll see that s nice and steady in flexion. It doesn t move, and yet it falls out all the way into extension. So this knee has excellent motion right now. 00:23:22 DR. GILES SCUDERI: That knee looks nice and stable. Looks like you got great motion. That little post on the tibial component is substituting for the ligaments we talked about earlier. 00:23:32 DR. ROBERT E. BOOTH, JR.: This is that post that s the replacement, if you will, for the cruciate ligaments, and it allows it also helps drive the knee. It doesn t work until the knee bends about 70 degrees, but once it does, the post engages, and so with stair climbing or other activities, this will force or help the knee to bend and achieve the proper range of motion. 00:23:52 DR. GILES SCUDERI: You know, we ve actually done scientific studies and fluoroscopy studies and kinematic analysis that shows that that cam mechanism has a very predictable range of motion. It s gets you predictable rollback, and I think that rollback is what gives us that high degree of flexion that we re able to achieve. 00:24:09 DR. ROBERT E. BOOTH, JR.: Well, people are still trying all different design concepts for knees. Everybody wants to create something that mimics best the the natural design. This is the closest we ve come. Nothing has ever exceeded this knee design in stability, in range of motion, and frankly, in the ability of surgeons to put it in repeatedly and accurately. I mean, a big part of this, obviously, is how my partners and I do this surgery, and this knee is, just frankly, simpler and easier to create a proper motion with. 00:24:46 DR. GILES SCUDERI: Now, at this point, you re preparing the kneecap, or the patella.

9 00:24:51 DR. ROBERT E. BOOTH, JR.: Now, this kneecap was actually was actually smaller than natural size because you saw it had been worn down, it had been eroded, just like two millstones rubbing on one another. This had worn down internally. So this kneecap is now back to something, and you can see something approximating its normal size. Bayonet. And what we re doing here is flexing and extending this knee. Michelle has the best view of it, but we can see that it s sitting perfectly in its little track. When I straighten the knee, that track goes off at a slight angle, more of an angle in a female than a male, and so this knee is built to accept that and to make it track more naturally and more reproducibly. 00:25:35 DR. GILES SCUDERI: So you ve tried to restore the anatomy of the kneecap. You re trying to restore the alignment of the kneecap, how it tracks in the groove. And we call that the Q angle. Do you think that the next-gen solution id the solution for patella tracking? 00:25:47 DR. ROBERT E. BOOTH, JR.: I think it solves most of my patellar-tracking problems. The most important part for me is the thinness of that anterior flange. I like that because particularly in this knee, I m not going to be overstuffing or putting more material in than I started with. 00:26:01 DR. GILES SCUDERI: Yeah, I think personally, that s the two main features in the change in the shape is one, that we ve reduced the height of that anterior flange so we don t overstuff the patellar femoral joint, and two, we ve increased the Q angle or the tracking angle of the kneecap. And I think that really helps the patient, especially the female patient, who has a gynecoid pelvis. It s a little bit wider, and females tend to have an increased Q angle. SO we can, you know, mechanically restore her anatomy with this device. 00:26:31 DR. ROBERT E. BOOTH, JR.: And I think these are provisionals. Obviously, they ve been sued and loved here already, and you can see they re a bit worn, but just holding these up in the light here, I think you can see that the gender knee on the right is more it s shaped more delicately than the one on the left. It s hard to see the three-degree angle. That s tough for your vision. But the other thing that s quite apparent from the beginning is that it s thinner. This is the gender knee. This is the regular knee, and you can see it s more delicate and not as thick up front, which is the way a woman s knee is as well. SO this has multiple advantages aside from just the different shape. 00:27:10 DR. GILES SCUDERI: I have a question from the audience. They wanted to know, specifically, how much narrower is it? 00:27:14 DR. ROBERT E. BOOTH, JR.: It depends on where you measure it, Gil. 00:27:17 DR. GILES SCUDERI: No, absolutely, and it really is dependent on the size of the implant and where you do measure the implant. But we have made all the implants proportionately narrower than the standard implant. 00:27:30 DR. ROBERT E. BOOTH, JR.: It s definitely narrower it s the narrowest implant on the market up front, and it s also the thinnest. I mean, all companies have to choose balances and choices, but this has the advantage of being the leader in both of those dimensions. And now if you can look once again remember when we looked before, this part was overhanging here. I think you can now is it s right up to the edge but

10 not overhanging. I ve put on a part that doesn t rub on the soft tissues and yet preserves the diameter of the knee front to back that will make it work well. 00:28:05 DR. GILES SCUDERI: You know, it s interesting, I looked at that knee again. It looked more trapezoidal with that implant in, similar to what we had before. So I mean, it looks like you ve almost restored the anatomy that you had before you even made all the bone cuts. 00:28:16 DR. ROBERT E. BOOTH, JR.: Right. Let s just try this patella again. I want to try my patella one more time to be sure that it tracks, because that s going to be an important issue for this lady. She s going to want to play sports. She s going to want to kneel, bend, things like that, which are an important part of her life. Good. 00:28:37 DR. GILES SCUDERI: There was a question from the audience: Do you let your patients kneel? 00:28:42 DR. ROBERT E. BOOTH, JR.: I do. There have been a couple studies on that. 85% of people will kneel after a total knee replacement, and they don t harm the knee at all. In fact, we have taken X-rays to show that when you kneel, you re really kneeling on your shinbone. 15% of people won t kneel because they re squeamish about it. Some are sore, but a lot of them are just upset because it just doesn t feel right, and no matter what you tell them, they don t believe that it s the right thing to do. 00:29:12 DR. GILES SCUDERI: Yeah, we actually did a similar radiographic study. We had our patients kneel on a pew which we brought into the radiology sweet, and they do kneel on their shinbone. Some of the patients felt uncomfortable, though, kneeling on the incision. And what I found is with the smaller-incision surgery that they re no longer kneeling on their surgical scar. We solved that problem with the approach. 00:29:31 DR. ROBERT E. BOOTH, JR.: And even this incision just goes down but not over the tuberosity, the thin part of the bone there. 00:29:38 DR. GILES SCUDERI: So now you clean the bony surfaces. 00:29:42 DR. ROBERT E. BOOTH, JR.: Well, we cement our parts. Again, there are two schools of thought. Some people like to use parts into which the bone grows. The numbers are just slightly better, at least in our hands, of using parts that are cemented to the bone, but it s not an adhesive. It doesn t stick to the bone. It s a grout. So it fills all the little holes, and to do that, we wash out the fat and the marrow from the little holes within the bone. 00:30:05 DR. GILES SCUDERI: I have a question from the audience, Bob. You and I are both surgeons that cement all our implants, and I have a question from Seth in the audience. And Seth says: Do you ever envision cementless fixations for this type of design? 00:30:18 DR. ROBERT E. BOOTH, JR.: Absolutely. As soon as someone persuades me, which I think may happen in the very near future, that there is a better way of getting bone to grow into the parts, I would move to it right away. There s a new material out called tantalum. Not a new material; it s an element on its own, but it s been adapted to allow bone to grow into it. It actually mimics bone. It s a metal that can be fabricated to look like, to imitate bone, and it also is much more elastic to match the modulus of elasticity of bone. So not only will it be a good bone in surface, I

11 think it will allow the bone around it to stay healthier because it s not shielded from the normal stresses as much. So that s probably the most promising material that would replace cement. 00:31:01 DR. GILES SCUDERI: Right now, I mean, Zimmer does have the Monoblock Tibial component, which is a High-Flex design that can be used with the High-Flex Gender femur. So we can almost do a hybrid knee at this point with our current implant inventory. 00:31:15 DR. ROBERT E. BOOTH, JR: Yes. Well, Philadelphia is an ultraconservative area, as you know. At least compared to New York, Gil, so I'll wait another short while before we mimic you in using that. 00:31:24 DR. GILES SCUDERI: Because we have been doing that. We have -- DR. ROBERT E. BOOTH, JR: Oh, I figured. DR. GILES SCUDERI: We have been using Trabecular Metal Monoblock cementless tibial components with the Gender femur, so we've -- we've found, in the younger patient who has good bone quality, that's probably the ideal candidate for it. 00:31:38 DR. ROBERT E. BOOTH, JR: Yeah, I think -- certainly healthier for the bone in the long run if it works, as well. 00:31:44 DR. GILES SCUDERI: So that's the cement now. Okay. So you coat the bone and you impact the thermal component. It's a very tight fit. 00:31:54 DR. ROBERT E. BOOTH, JR: There's not a lot of room for the cement, and it's forced into the little holes and interstices in the bone. That's how it works, by filling those pores just like the bathroom tile in your house; the grout fills the porosities in the ceramic tile. 00:32:08 DR. GILES SCUDERI: You know, sometimes you get sclerotic bone, though, you know. Maybe in the valgus knee, and you've had a hypoplastic lateral femoral condyle. Do you prepare the bone any way? I usually put some drill holes in it or scuff it up so I get some penetration. 00:32:20 DR. ROBERT E. BOOTH, JR: You'd like to get something into the softer bone because this stuff won't stick to marble, obviously, and so, yes, this lady's not -- doesn't require that. 00:32:30 DR. GILES SCUDERI: Yeah, her bone looks pretty good. 00:32:32 DR. ROBERT E. BOOTH, JR: Well, she's been very active and young. She takes her -- appropriate medications and she's obviously going to outlive me, I think, so... 00:32:47 DR. GILES SCUDERI: So this is the sequence that you usually do? Femur followed by the tibia. 00:32:50 DR. ROBERT E. BOOTH, JR: Well, again, I -- I like to think the -- The series of problems that a surgeon faces here balancing a knee is complex, about getting it just right in both flexion and extension. And usually those problems are easier are easier if you get the knee in flexion first, so you know, when we do revision knees and redo knees why -- we teach people to do the -- the flexion side first because it creates an easier set of problems to solve.

12 00:33:18 DR. GILES SCUDERI: It looks like you do a pretty thorough cleaning of that excessive cement. I think that s important. 00:33:24 DR. ROBERT E. BOOTH, JR: Yep. Michelle is really quick and can get this off very rapidly. It sets in five to eight minutes, depending on the temperature of the room and how Leslie s cooking is on any particular day. So we only have a few minutes to get this secure. And again, as we put pressure on it by straightening the leg or by putting this clamp, for instance, on it, it pushes it forces the cement into the holes in the bone. 00:33:48 DR. GILES SCUDERI: I have a question here from Alex in the audience. Say a patient has patella alta. Is there any contraindications or risks with the High-Flex knee? 00:33:48 DR. ROBERT E. BOOTH, JR: I don t think so. Patella alta really isn t much of a problem with us. The opposite is, with a low patella, because sometimes that will limit your motion. But I have not seen any subluxations or other problems with the patella. I think it puts more pressure on the surgeon to get the rotation of the parts just right. Obviously, you can t have many deviations from being right on if you re going to keep that patella in the groove and tracking normally. 00:34:23 DR. GILES SCUDERI: Yeah, I think those patients who have a patella alta usually have a good range of motion. I mean, they usually have almost a full, complete range of motion, and that s why I think the High-Flex implant is ideal for them. The other nice feature of the High-Flex implant is that the tibial component has an anterior recess, so that reduces any impingement of the patella tendon or the fat pad. So I think it s specifically designed, again, for that patient who has patella alta. And I agree with you, Bob. There s no contraindication to doing this procedure with a High-Flex implant in a patient who has patella alta. Now you put a drain in the knee. Do you use a reinfusion drain or is this just a hemovac drain to collect the blood? 00:35:02 DR. ROBERT E. BOOTH, JR: This is a reinfusion drain. We have a cardiac team here who s not as busy as I guess they d like to be with heart surgery, so they re very nice to us. They come help filter and give this blood, the patient s blood, back to them in the recovery room. 00:35:17 DR. GILES SCUDERI: Yeah, I like to use a reinfusion drain. We actual do bloodless surgery in New York, we like to say, on our unilateral knees. We check our patient s blood count before the surgery. We may give them some medication to increase their blood count. But we use a reinfusion drain and we don t have them donate any blood. 00:35:37 DR. ROBERT E. BOOTH, JR: Well, that s certainly the ideal. 00:35:39 DR. GILES SCUDERI: I have a question from Vicky, Bob. How long has the Zimmer Gender knee been in use? You and I were the design surgeons. We ve been doing it from the inception. 00:35:45 DR. ROBERT E. BOOTH, JR: Since it s been the second week in May we started putting these in. And I think, frankly, I was a little surprised that it got FDA approval so rapidly. I was expecting to have to wait another year because our government usually takes a very long time to be sure things are right. But this is an idea -- it s embarrassing, frankly, Gil, to think it was only nine or ten years ago that we went to

13 using right and left knees. If you had a knee ten years ago, there was sort of a Fruit of the Loom one shape fits all concept. And so, when we went to rights and lefts, it s like selling right and left shoes. It just seemed so obvious. I think this is very akin to the same idea. The government said, This is obviously an improvement, and passed it through quickly. So we ve only been doing these for four months, basically. We ve got about 250 of them in here, and we ve been extremely happy so far. 00:36:35 DR. GILES SCUDERI: We also have a very high volume of cases, and one nice feature of this implant: it s designed off of a very successful implant that we have been utilizing in the past. I mean, we have had the High-Flex LPS for over five years, and we ve been very, very successful. And this, again, as I mentioned earlier, gives me more implant choices. I can now customize that implant to make my intraoperative decisions using an implant that I ve been very happy with for over five years with great clinical success. 00:37:05 DR. ROBERT E. BOOTH, JR: Yeah, two of the things I like best are that this design doesn t change at all the basic mechanics of what s been the most successful knee thus far. So I don t have to worry that I m changing or experimenting with something that s a significant change from what I ve come to trust over the past 10 years. And the second part is it s consistent with other initiatives from Zimmer, such as High-Flex and minimally invasive. The nice thing is, no matter what you do as a surgeon, whether you re minimally invasive or not, or like High-Flex or not, everybody can use this knee, and it makes them a little bit better. It s not that you have to change your philosophy or change your instruments or change what you believe about knees. This just makes you better because it fits better. 00:37:48 DR. GILES SCUDERI: I just want to build on that, Bob, because the most important thing is you don t have to change your surgical technique. 00:37:52 REB: Right. 00:37:53 DR. GILES SCUDERI: This is how you do your knee. We re just going to give you an implant that has a better shape, a better size for that particular patient. You don t have to change your surgical technique. Now we re you know, we are posterior stabilized surgeons. We prefer an LPS prosthesis. But you can, and there is a cruciate-retaining design in Gender. 00:38:13 DR. ROBERT E. BOOTH, JR: Yes. 00:38:15 DR. GILES SCUDERI: So remember that. I mean, we do have our bias, we do have our bias. We are trained by John Insall and we are big advocates of a posterior stabilized knee for all the reasons mentioned earlier. But again, there has been success, you know, with the Gender Cruciate Retaining Knee. And again, you don t have to change your surgical technique. 00:38:32 DR. ROBERT E. BOOTH, JR: Exactly. 00:38:35 DR. GILES SCUDERI: I have a question from the audience again, Bob. How about revision knees? Can you use this implant on a revision knee? 00:38:40 DR. ROBERT E. BOOTH, JR: You can to a certain limit. Some revision knees are really just a matter of changing one component or making fairly routine changes. And if the bone is good, you can put this in in a revision situation. However, if you need

14 stems or special augments or are replacing big bone defects, then you need a more what I call an industrial strength knee that has a lot of other aspects to it that sort of override the gender issue for the moment. I think that will come, but right now it s primarily for it s essentially for primary knees and for easy revisions. 00:39:18 DR. GILES SCUDERI: Bob, I have another question from John. We probably both can answer this. What percentage of your patients are women? 00:39:25 DR. ROBERT E. BOOTH, JR: Well, it s probably 65, 70%. And of them about, I would say 75% are candidates for one of those three reasons: needing a thinner flange or higher Q angle or different shape. So for one or all of those reasons, I would say about 70% of women are eligible for this on an anatomic basis. What s been striking to me is the women almost uniformly ask for it now. Now that women have heard about this, they want this. When they hear that knees for 20 or 25 years have been designed sort of based on male anatomy, there s this moment of indignation where they re not happy once again that it s been our world for too long. And so now that they know that there s something that s made for them, they are clearly in the mind to have it. 00:40:13 DR. GILES SCUDERI: I think women are more educated consumers, more educated than men. I think men are a little more complacent about it. Women do ask a lot more questions when it comes to the office. You re absolutely right. They re asking me more about the Gender knee than ever before, especially with some of the recent publicity about the Gender knee. It s about two-thirds of my patients. But historically, as we look at total knee replacement, about two-thirds of the patients are female, and the majority of them would be candidates. In my hands, it s about 80, 85% of my patients currently in the female population are getting a Gender knee. 00:40:50 DR. ROBERT E. BOOTH, JR: Now, what s interesting to me, Gil, is that about 10% of the men we see are candidates for this as well. Patellofemoral arthritis, for instance, is nine times as common in women as men, but there are men who get it, and I think this is an appropriate knee for them. And we indeed have put half a dozen of these in men already as well. 00:41:10 DR. GILES SCUDERI: Yeah, that was going to be my next question, Bob, too. When you do encounter a male patient and his anatomy is such it may be a little more trapezoidal would you put that Gender knee in? And I agree with you. I think that that s appropriate because that knee is now replacing his anatomy, and we re just trying to give him back the anatomy that he has. Total knees are always a bunch of compromises, a series of compromises that you make. And this reduces the amount of compromises that we have to make. 00:41:33 DR. ROBERT E. BOOTH, JR: And it s not just gender. It s also for instance, most people with rheumatoid arthritis have knees that are shaped like women s knees, that are narrow. In fact, almost 100% of the people that I see. Now that s a disease that s mercifully disappearing from our society because of the new TNF inhibitor drugs that are available, but we still some of them for joint replacement. I know you do too. And their knees are very much of the female configuration. 00:41:57 DR. GILES SCUDERI: For the surgeons group, they may ask is this for a varus knee or a valgus knee. You know, valgus knees have a little bit more of a hypoplastic

15 lateral femoral condyle and they tend to be a little bit narrower. Do you find any differences at all with the deformity of the knee? 00:42:12 DR. ROBERT E. BOOTH, JR: Well, valgus knees, of course, may have a tracking angle that needs to be dealt with, and that certainly is a piece of this knee that would be helpful. The reality is that valgus knees are far more common in women than in men. So once again, whether it s an anatomic issue or a gender issue, I m not really sure. But certainly, if I see a valgus knee, it s far more likely to have a female, whether it s independent of sex. 00:42:35 DR. GILES SCUDERI: And I think the other point there, again, for the surgeons in the group, is that the trochlear and the patellar tracking is different in a varus and valgus knee. And again, because we ve widened the trochlear, I think this is more accommodating to those particular knee designs. 00:42:50 DR. ROBERT E. BOOTH, JR: Yes. 00:42:55 DR. GILES SCUDERI: Well, Bob, we ve got a little bit more time, which is good. It gives us an opportunity to talk a little bit about knees and the new total knee patient. You know, we re seeing a lot of younger patients. The baby boomers are now coming of age, they re active, they want more function, they want more motion. As we ve just talked about, they are females predominantly and they have different anatomic features. I mean, are you seeing that change? Are you seeing more baby boomers coming about? 00:43:25 DR. ROBERT E. BOOTH, JR: Absolutely. I think a lot of it is their pain tolerance. The greatest generation, the ones we still see a few of, in their 80s and such, have a difference response to pain. The men won t even use the word pain sometimes; they talk about stiffness or aching. The women will describe it, but not quite as enthusiastically as the baby boomer women. A lot of those older girls have been through a Depression, a couple World Wars, usually a couple husbands, and so they re pretty tough, but the baby boomers are a little more verbal. And women have a much better vocabulary for pain than we men do. I mean, it s like colors. You and I know red, blue, green; they know mauve, taupe, chartreuse, words we don t even exactly know And they re the same way with pain. They re very good at describing the particularities of it. And as we listen to them more, we re going to have to deal with their complaints more and solve the problem for them. 00:44:19 DR. GILES SCUDERI: You know, it s interesting also that these patients want more function out of their knee. What I try to explain to my patients is while it is the implant design that specifically designed for high-flexion, they re part of the team too. They have to work with us to get their motion, they have to participate in their rehab, they have to be compliant with the instructions we give them. But sometimes it s the knee replacement itself, that environment that we put the knee in. Why do some knees get stiff? And it s what we do, but sometimes it s what they do, and some things that are out of our control. 00:44:49 DR. ROBERT E. BOOTH, JR: It s very much a partnership. I mean, every knee surgeon has knees that just look absolutely perfect, and you know they re perfect, and the patient never quite got the motion that you d hope. And you re as disappointed as they are probably, but it is a partnership. It s that interface between biology and technology, between skill and the psychology of the patient that s hard to pin down. So part of the responsibility for us is to pick people in advance who

16 realize this is a serious operation. Sometimes when you hear about minimally invasive surgery and rapid recuperation and parts that make you have more motion, you think, Gee, they re going to do it all for me. This is already done. And we have to keep reminding them and ourselves that this takes work to get a good result from a knee. 00:45:34 DR. GILES SCUDERI: Yeah, I think that s fair. It s a partnership. I tell my patients they re part of the team, just as my assistant is, my P.A. They re part of the team because they re going to help me get a good result out of their knee. And it s very, very important. You know, I put this slide up is why a gender knee? And I think we ve covered much of this in our discussion in the recent half-hour, 45 minutes. But really, 62% of the total knees are performed in women. I mean, and they are, as we said, a very educated consumer. Do you have any other input on this, Bob? We are finding it s a different patient population right now. 0:46:08 DR. ROBERT E. BOOTH, JR: They still outlive us, so their opportunity to wear out their joints and need a knee exceeds ours. Obesity is a big problem in our society, and it s more common in women than men. So the person who s going to be getting most of the total knee is the profile of the person who s going to get most of the total knees in the future is obese, osteoporotic, late middle age women. I mean, that s who s wearing their joints out. The nice thing is if you can fix their knees, you actually can contribute to them solving their obesity problem. You and I both see people who come whose knees are worn out. They really can t exercise. The only way they can lose weight is to starve themselves. 00:46:47 DR. GILES SCUDERI: And you re in a catch :46:48 DR. ROBERT E. BOOTH, JR: So if you fix their knees, at least you re giving them the other piece of the equation to help with their weight problem. We ve got drugs for osteoporosis. The real issue I see is it s a lifestyle change. The people who want to get a knee so that they can lead that s more appropriate for their years, they re the ones who do the best of all. I think something interesting is going to happen with the Chinese Olympics. If you think back to the last Olympics, what comes to my mind are our women s athletic teams. And I think it s going to be even more that way in China for the next Olympics. And I think that s going to drive more and more women into sports and into situations where they re going to need knees when they re older. So I think the demand is going to increase from that side of the scale. 00:47:27 DR. GILES SCUDERI: Well, we ve seen that with Title 9 women are more involved in sports than ever before. The number of injuries has definitely escalated, and we re seeing more and more women from years of sports now coming to us with worn-out knees. Let s just talk about implant design and where. One feature we haven t talked about is the polyethylene. Personally, I use Prolong poly. It s a crosslinked poly. It s designed, again, for a more long-lasting implant. And I ve been happy with that. I mean, are you using crosslinked poly? 00:47:58 DR. ROBERT E. BOOTH, JR: I ve been using it for a couple years now, yes. And the polyethylene technology has changed 15 times in the years that you and I have been putting knees in. This is the thing that aside from just buying the best polyethylene seems to have made the biggest impact and the most positive impact. And obviously, a lot of people know about cross-linking it and how to make it tighter and more resistant. And it s different in knees than hips. I think we ve learned not to automatically imitate everything we do in the hip because the knee is a very

17 different joint. And now that we have plastics for the knee that are treated in such a way to accommodate the different motion in a knee, I think they re going to be the best we ve had ever, ever, and the best so far. 00:48:37 DR. GILES SCUDERI: Yeah, I think that the lab testing on the Prolong Poly has been fantastic. I mean, we showed a great reduction in the wear characteristics, the delamination. And you know, my first concern was that tibial post, as we showed during the operation, that substitution. The mechanical testing has been equivalent to the standard polyethylene, so I think we re on the right track. And I think Zimmer s got a good product with their Prolong Poly, you know, for this high-flex high-demand patient, that it should at least bear out as well if not a lot better than what we ve seen in some of the polyethylene in the past. 00:49:09 DR. ROBERT E. BOOTH, JR: It s interesting you mention the post. I hadn t thought about it until you just said it, but you know, for years people have criticized that part of the design. And one of the reasons the post had problems is that we had to downsize components. And now we don t have to downsize components anymore, so this may solve some of those posts problems that we ve seen in the past as well. 00:49:28 DR. GILES SCUDERI: Let s talk a little about the implant itself and let s talk about the trochlear design, because I think that differentiates us from some of the other implants that are out there. We talk about the implant being narrower, but we have spent specific time, we have spent detail on trying to improve that trochlear design. I put this slide up because I think some of the traditional implants do overstuff that female knee and that we ve been able to narrow lower the height of that anterior flange. I think that s a great benefit. And I heard you talk about that especially for this case with patellofemoral arthritis. 00:50:03 DR. ROBERT E. BOOTH, JR: I picked this case particularly because, as I said, when I first started using these knees I thought it would be the shape issue that would be the number one reason I would put it in. And it really is this thinner flange that I find the most attractive feature of all, and also what makes it more common in men, that this is the aspect of the knee that better suits the men. So making it more delicate, more thinner and just not forcing us to overstuff the knee as we have in the past is a big step forward. It s a different level of sophistication that we re at now. We just can t put generic, standard parts in anymore. We re now reaching a new level, I think, of knee surgery, and I m happy I m around to still see it and contribute to it. 00:50:49 DR. GILES SCUDERI: You know, that brought up a question again from the audience. They ask, Do you choose this implant for all your female patients? Do you preoperatively determine that that woman is going to get a Gender knee? 00:51:02 DR. ROBERT E. BOOTH, JR: Well, it s tough we ve been trying to find an x-ray technique that would look at the shape of the knee and predict who was going to need it and who would not. And so far, I ve not been terribly successful with that. The reality is, if you figure two-thirds of your patients are women and two-thirds are candidates for the knee, then just playing the odds, I think we ought to be preparing the female knee from the beginning. And then only if it looks like the bone is not well-covered would we switch to the standard knee. I m really hard-pressed to think of a reason not to use the female knee right now. I think there s no negative to it at the moment. 00:51:34

18 DR. GILES SCUDERI: Yeah, Bob, I put this slide up too just to bring up a point that we were just talking about, can we determine preoperatively who s ideal. And these are some of the differences I ve seen under the lateral x-rays between a male and a female knee. And as the arrows indicate that the trochlear, the anterior cortex, is a lot lower in that female knee. I think this is a perfect candidate for a Gender knee when you have this very low profile. And I look very carefully at all my lateral x-rays, you know, and I talk to the patients about that in the office, you know, to try and explain that to them. So this is at least one screening tool that I think is very, very helpful, and it s quite easy to obtain. 00:52:09 DR. ROBERT E. BOOTH, JR: And this is exactly what John Insall was looking at 15 years ago, and this is precisely the image that made him ask the companies to create that one special design for him to deal with this very issue. 00:52:24 DR. GILES SCUDERI: We talk about the tracking of the patella and the groove. We talk about the q angle. And we know that the female knee is very much different in the way the kneecap tracks. And again, this design, the Gender Solutions, has a wider groove. The trochlear groove is now ten degrees versus seven degrees. Do you think that three degrees matters that much? 00:52:49 DR. ROBERT E. BOOTH, JR: Well, we re down to this is a game of millimeters, knee surgery. A millimeter equals a degree around the knee, that s the little rule we all use. And sure, three degrees makes a significant difference here. Some people have trouble understanding this. I tell women to put their arm out with their hand palmup, and if you look at their arms, they re almost all at an angle. Most men s arms are straight. And you wouldn t design a sleeve or coat to fit a straight arm if it was off at an angle. It s just a matter of making the shape fit the shape of the person it was intended for. So I think this is a significant difference because three degrees means a lot to us at the level of the knee. 00:53:24 DR. GILES SCUDERI: I think it does, also. And I think that the added benefit is to what we discussed before. You don t have to change your surgical technique. I could put that implant exactly the way I did before, and I get the benefit of that extra three degrees with my same technique. 00:53:42 DR. ROBERT E. BOOTH, JR: The patellofemoral joint s always sort of been the stepchild of knee replacement. We ve worried about the tibia and the femur and all that, and we don t pay as much attention to this, frankly, as we might. It s always the last part of the case we do, for most of us. What people don t realize is getting out of a chair or climbing stairs, the force across that patellofemoral joint is seven or eight times your body weight. So you do your own math. We all know what we weigh. Take that, multiply it by eight, you realize how much pressure there is on that joint. And if it s not lined up just right, it magnifies any flaw or any imperfection. 00:54:12 DR. GILES SCUDERI: You know, the NextGen Trochlear has been so successful we actually showed that it s a more anatomic-appearing trochlear, even with the standard LPS flex implant. We ve got no soft tissue impingement. The old clunk issues, I think, actually came out of Philadelphia, right? 00:54:26 DR. ROBERT E. BOOTH, JR: We created a lot of clunks 00:54:30 DR. GILES SCUDERI: We resolved that issue with this trochlear design, and now we ve made it even better.

19 00:54:34 DR. ROBERT E. BOOTH, JR: Well as you know, there s another group of surgeons aside from you and I who don t like to put a plastic button underneath a kneecap, and this trochlear, I think well, it already fits those natural patellae better, but I think it will work even better for them as well. It s not just for those of us who put a plastic button there. 00:54:50 DR. GILES SCUDERI: Well, let s go to the audience. I have a question from Matt, and Matt asks, Should we be cautious about adding any external rotation to the femur with this design? So I guess femoral component rotation, would we do anything different? And personally, I don t think you do. As you drew in the upper condylar axis, the AP axis, we re restoring the appropriate functional axis of the knee. 00:55:11 DR. ROBERT E. BOOTH, JR: Again, it s a level of sophistication. I agree with you wholeheartedly. The problem right now is that most of the knees in this country are put in using instrument systems that dictate a certain fixed number of rotation three degrees is the magic number we all use. And I think most of the surgeons who do very high volumes of knees know that that s quite a range. It s been documented with CAT scans and MRIs to be somewhere between zero and nine degrees. So we tend to fiddle with that number. I don t think many of us put it in at one specific number. The people who would be candidates for a Gender knee are usually women, and usually women with a higher q angle, and they re often the same people who have more than three degrees. So to answer Matt s question, yes, you don t want to put in too much external rotation. But by and large, people who have valgus knees and this type of knee that we just saw have a little more than three degrees of rotation. And we need to accommodate that. We need to match that with the way we put the part in. 00:56:06 DR. GILES SCUDERI: Yeah, I mean, there s no cookbook answer to the rotation of the component. We really want to try to get those anatomic measurements: the AP axis, the upper condylar axis, trying to get that, because that s also going to drive that flexion gap. And that can give us problems from a very technical point of view in the balancing of that knee. We could get liftoff, which is not a good thing within the knee. I have a question from Tim in the audience, and Tim says, With a high-flex knee, can you expect more flexion after your surgery, the same or less? I guess I ll take that one. 00:56:36 DR. ROBERT E. BOOTH, JR: Yeah, that s your wheel house there. Go for it. 00:56:39 DR. GILES SCUDERI: With the High-Flex knee, what s really important is that the patient understand what their preoperative motion was because that definitely drives your preoperative drives your postoperative range of motion. But our anatomic clinical follow-up studies have shown that we have been able to regain about 10 percent, about more degrees. Our average range of motion postoperatively is about 139 degrees when their preoperative range of motion was about 125. So our patients get about 10 to 15 percent more motion than they had before. 00:57:15 DR. ROBERT E. BOOTH, JR: That s terrific. And again, it s so much part of the partnership thing. You and I both know if we see somebody in our office who s got a very arthritic knee but still has very good motion, they re going to get a good result, one, because they got good motion, but two, because it suggests they handle pain pretty well. When you see somebody whose knee doesn t look that bad and it s very

20 stiff and painful, it may have more to say about their pain tolerance than it does about the state of the arthritis. So it s a double issue. 00:57:41 DR. GILES SCUDERI: You know, it s interesting, too, if we look at the surgeons of the group, a lot of reports have shown a very successful result with the LSP Flex implant and very comparable to our own experience. And it s both surgical technique-driven as well as implant-driven. A question from Sharon in the audience. This is a good one. Sharon asks, Is there such a thing as implant failure? Do implants fail? 00:58:06 DR. ROBERT E. BOOTH, JR: Of course. 00:58:07 DR. GILES SCUDERI: We re both going to say yes to that one. There s no doubt about it. 00:58:10 DR. ROBERT E. BOOTH, JR: When you and I first started putting knees in, the materials would fail. The parts would break, the plastic would wear very quickly. Implant failure meant a whole different thing back then, and that rarely happens now. I don t think I ve seen a broken part in ten year, frankly. The parts wear, there s no question about that. The plastic in the middle of every joint, whether it s a knee or hip or whatever, is the sacrificial element, just like the rubber wears on your car tire, just like the Teflon on your frying pan. So we know there s going to be wear, but that rate theoretically will not be such that it will cause the prosthesis to fail before you re finished using it. We apologize often for our success rates. John Insall s numbers were 98% success at ten years and roughly 93-94% at 20 years. And when we apologize for that, cars don t last that long, houses, marriages don t last that long. I mean, that s actually a really good number if you think about it. We need to keep improving it, and I think this sort of thing will improve it a little bit more. 00:59:07 DR. GILES SCUDERI: Yeah, I think you re absolutely right. There s a lot of variables that go into a failing implant, but fortunately, it s a low number, though. Fortunately, it s a very low number, and it s not something that is escalating. But unfortunately, the number of cases have been increasing only because the sheer volume of total knees have been increasing. So the more knees you put in, the more you fail, but fortunately that number is still low. And the nice thing about current implant designs is we ve gotten better with the materials, we ve improved our surgical technique. And I think that s the most important thing is we refined our surgical techniques. We re not seeing as much of a problem as we did before. 00:59:47 DR. ROBERT E. BOOTH, JR: I m happy that you and I are in this era of knee replacement, or joint replacement, because this has been an exciting ride and a few more changes to come, I think. 00:59:55 DR. GILES SCUDERI: Absolutely. You know, I think with our new implant right now, our Gender Solution with the High-Flex knee, we ve really designed an implant that s going to benefit our patients. We ve designed an implant that s going to be very, very successful and I think is going to have a longevity for all of us. So I want to thank everybody for spending time with us this evening. It s been a pleasure, Bob, to watch you operate. Bob, any last comments to close? 01:00:23 DR. ROBERT E. BOOTH, JR: No, I m just happy to be part of this, as I said, and look forward to the future. There s more good things to come and I m pleased particularly that the women in our population will be served so well by this new part. 01:01:35