Watch a surgical webcast featuring the Smith & Nephew JOURNEY™ II Cruciate Retaining (CR) Knee System. David Rovinsky, MD, of Wilcox Health, performs the procedure at Kauai Medical Clinic in Lihue, HI. Michael Ries, MD, Chief of the UCSF Arthroplasty service, as well as a professor of Orthopedic Surgery at UC Berkley and UC San Fransisco, moderates throughout the knee replacement.
For orthopaedic surgeons seeking treatment solutions beyond traditional knee replacements, the JOURNEY™ II Cruciate Retaining Knee has been engineered to empower patients with a renewed right to an active lifestyle by breaking through traditional knee replacement barriers and delivers Function, Motion and Durability through PHYSIOLOGICAL MATCHING Technology. The webcast premiered at 8:00 PM EDT (2:00 PM HAST) on Thursday, May 1, 2014. Viewers where able to submit questions during the webcast, which the surgeons answered live immediately following the procedure. MIKE RIES: I'm Mike Ries. I want to welcome you to our program. We're in Kauai at Wilcox Hospital where Dave Ravinsky is going to be doing a JOURNEY surgery. He's getting the patient ready and we should be going pretty soon. But in the time we've got now, I wanted to introduce you to some of the JOURNEY concepts and go through a little bit of the design rationale and the development of JOURNEY to produce a knee that has more normal kinematics than a conventional knee. One of the goals of JOURNEY is to improve upon prior knee designs and make a more kinematically correct knee with the goal of improving knee function. The JOURNEY Knee was designed to reproduce more normal kinematics. Kinematics of the hip are quite different than the knee after replacement, in that the hip is a ball and socket joint. The replace joint works more like a normal hip, but the knee is more complicated, with four ligaments that are altered a bit with the replacement. And this can translate into altered kinematics after knee replacement. This may explain some of the differences in patient satisfaction between hips and knees. This is a survey done by Phil Noble, which queried 243 knee replacement patients in comparison to age and gender matched controls and showed a substantial difference in the activities that could be achieved by the two groups. The knee replacement patients had difficulty with activities such as squatting, cutting, turning. And many of these patients had expected to be able to do that after knee replacement, which can lead to use dissatisfaction. This is a comparison of patients with hip compared to knee replacement and their ability to return to sports. After hip replacement, 52% could participate in low impact sports, while 36% could do that pre-operatively, so an improvement in sports participation after hip replacement but the opposite after knee replacement, a decrease from 42% participation in low activity sports to 34% after knee replacement. And these are not high demand activities, but things such as golf, swimming, doubles tennis, maybe, that you would expect patients to be able to accomplish after joint replacement and may be a source of dissatisfaction after knee replacement. Now, one of the reasons for this can be related to the kinematics. If you look at the kinematics of the normal knee, shown here on the video on the left, you can see the contact points on the medial on the right and lateral on the left side of knee of the tibia. The lateral contact point starts anteriorly and has quite a bit of posterior excursion, resulting in femoral external rotation during knee flexion. And this really accomplishes two things. It allows full flexion of the knee and also helps patellar trapping since, as the femur externally rotates, the tibia internally rotates, or it medializes the tibial tubercle. This is a videofluoroscopy of a conventional knee replacement showing a lack of external rotation during knee flexion, which is not surprising since it's primarily guided by the collateral ligaments, doesn't really have the cruciate ligaments or much in the way of characteristics of the articular surfaces that would facilitate femoral external rotation during knee flexion. Because it's sort of an ACL deficient knee, the knee replacement that you can see on the right, the tibia is kind of subluxed anteriorly. If we look at the posterior part of the femoral condyle, and the tibia of the normal knee on the left, they line up with one another, since the ACL is intact. But without that, the femur sits a little bit posterior, which is unphysiologic in extension. And then during flexion, it moves anteriorly, that is, paradoxical motion. Again, this shows the movement of the normal knee, showing the external rotation during knee flexion, which is a desirable kinematic pattern. And what you see on the right, is the same image with the JOURNEY Knee, illustrating the external rotation during knee flexion that's accomplished by having asymmetric tibial geometries and some unique characteristics of the cam-post mechanism in the bicruciate substituting, as well as the femoral component design that allow femoral external rotation during knee flexion to occur. And this illustrates the previous comparison of the two images on the left. The normal knee showing how the posterior part of the femoral condyle and tibial plateau are well aligned, the typical cruciate-retaining knee, where there's a posterior positioning of the femur, relative to the tibia and extension. And then a JOURNEY cruciate-retaining, the third one in, starting from the left to the right, where, once again, the two are aligned to one another, as there's a mechanism to contain the position of the femoral component over the tibia. And the same with the bicruciate-retaining, shown on the far right, the JOURNEY bicruciate substituting knee. And this illustrates the differences between the medial and lateral condyles or tibial plateaus. On the medial side, shown at the bottom, there's relative concavity of the medial tibial plateau. So it kind of contains the medial femoral condyle, almost like a ball and socket. It doesn't really allow it to move much anteriorly or posteriorly, while the lateral side, shown at the top has a convexity in the AP plane. It's concave in the ML plane, so that there's still adequate joint contact forces on the polyethylene maintained to minimize wear. But what this does is, it allows or encourages rollback on the lateral side, while containing the medial contact point, thereby producing femoral external rotation during flexion. And you can see the corresponding anatomy on the femur is to reproduce the physiologic or normal joint line of three degrees of varus. The bone cuts are made perpendicular to the mechanical axis. But the joint line is in three degrees of varus, which is a physiological orientation. And this illustrates the contact point in the midline with the femur directly over the tibia on the left, showing the reproduction of ACL type function by the geometry of the joint surfaces, particularly the conformity of the medial femoral condyle and tibial plateau. And the posterior medial lip, which prevents rollback on the medial side, while it allows it on the lateral side. And as the PCL engages, this encourages lateral femoral roll back or external rotation during refluxion and avoids the paradoxical motion of the anterior subluxation of the femur during knee flexion. MIKE RIES: I'm in Kauai with David Rabinsky, who's going to doing a CR JOURNEY Knee on one of his patients. And the JOURNEY has been developed to provide a more kinematically correct knee to what we've had available in the past. And initially with the bicruciate substituting. And more recently, a cruciate-retaining version that you'll see today. So that's our plan. I'll turn things over to Doctor Rabinsky and ask him to tell you a little bit about his patient and our plans from here. DAVID RABINSKY: Thanks. It's really a pleasure. Aloha from Kauai. So this is our patient today. She's in her late '60s. And she's a retired paramedic. And she really defines what we're considering our modern total knee patient. We're in Hawaii. And as you can imagine, she loves to surf. She loves to stand up paddle. She loves to swim. And she needs a knee that's going to let her do that. She needs a knee that's stable, lets her squat, that lets her kneel. And the benefits of the CR are really realized in this patient. So the age is not as important as the activity. And I think you'll see, and we'll point out some of the design features as we go along, why this is such a good knee for this type of patient. When we look at the films, we're doing her left knee. You can see typical varus pattern with medial wear. She also has severe patella femoral arthritis. And let's get going. You know, for this patient we're going to do our standard mini midvastus approach. I don't worry too much about the length of the incision. I worry more about the positioning of the incision. I want to be a little bit medial to the bony prominences, so that when she does kneel, she doesn't have pressure on the wound. And you certainly could do this through a smaller incision and using any approach you wish. This is just what we're choosing to do here. MIKE RIES: And just as a reminder, if anybody has questions out there, there's a mechanism to forward them in and we'll try to deal with them as they come. DAVID RABINSKY: Let's incise a little piece of this synovium here. This enhances our exposure. And the rest of the approach, you can do with our bovie. So this patient's had a prior knee arthroscopy. So sometimes that creates a little scar tissue anteriorly, but not too problematic in general. The JOURNEY design is really low profile up on this anterior femur. And we want to make sure that we're putting our cut right on that anterior cortex to optimize that design feature of having a narrow anterior phlange. So we take out pretty much the entire fat pad. I think that helps a lot with exposure. MIKE RIES: I guess it may have some circulation, the venous circulation from the patella, but since we're really not doing lateral releases anymore, probably doesn't. No downside to that either. DAVID RABINSKY: We really done much yet, and we can already pretty much evert the patella. Sometimes I'll do a little bit of release here. MIKE RIES: Is that the patella from the ligament more than retinaculum you release? DAVID RABINSKY: Yeah, I always release that. I just want to make sure I can easily evert the patella. There's no harm in doing that. MIKE RIES: Sure. DAVID RABINSKY: And now we're kind of ready to flex the knee up, but we haven't really done a lot of damage yet to the extensor mechanism. So we take our pickup and we want to take what we can see when we can see it. I want to release this anterior horn of the lateral meniscus. So I have a place for my retractor. And then I'll take this portion of the medial meniscus, just because I'm looking right at it. And we'll get the rest of it when we more towards the back of the knee. So I'm going to, just to immobilize things, cut our ACL. And we're going to be more judicious about this a little bit later. And for my landmark on my rotation, I want to mark Whiteside's line. I'm going to be in your way while I eyeball it. So, the next step is to make our entry point. And when we look at our preoperative x-rays, we're going to see what's going to put us right down the pike. And it's going to be just cheated a little bit medial, when we make our drill hole. So we're going to be going a little bit-- Yep. And I let the drill bit draw me up into the femoral canal. Just let it guide it. I don't want to be directing it. We're letting the medullary canal, the femur, show us where we're going. We're choosing six degrees of Valgus cut This is embarrassing. We're going to correct that. And I just let this sit down. And I just want to see that we're kind of in the ballpark of a rotational alignment. And we have a small matter of flexion contracture, so we're going to take a plus 2 distal femoral cut. DAVID RABINSKY: Is that going to put you about the base of the trochlear groove? Do you look at that also? DAVID RABINSKY: That's what we look at. And we can take our cut checker and just really double check that we're going to put this where we want it to be. MIKE RIES: OK. DAVID RABINSKY: See the swoosh? MIKE RIES: Because in a PS or more deformed knee, you might want to take a little bit more with flexion contracture deformity. But CR probably not a good idea to take too much of the distal femur. DAVID RABINSKY: You have to strike a balance when you're doing the CR knee. We have a slap hammer. When you take your PCL, you're going to be gaining two millimeters in your flexion gap. So we want to make sure our flexion gap and extension gaps are equal. And this is going right through here. And this is right at the sulcus. We're right where we want to be. MIKE RIES: One thing I'll do is, you see how the tip of it is right in your hole? Right in your IM hole. I think that's when you put it through the middle just where you had it, I think that's a good secondary check. And let's place our retractors and then we'll take this out. MIKE RIES: So you're putting in that oblique pin to keep it from sliding out when you do your saw cut? DAVID RABINSKY: Yes. This will help hold the block securely. [SAWING] And this gives us a check that we got a nice thickness of our cut and that it really is just a hair's breath deeper than our entry hole. So this cutting block has holes in it. If you don't like this cut, you can pretty easily adjust your depth and increase the depth of your cut. So the next step here is we're going to translocate the tibia anteriorly. Again, you let this kind of take you down. MIKE RIES: And it looks like you're doing the same thing there. You're letting that find it's way by not turning it on full speed. DAVID RABINSKY: It's a very aggressive drill bit. The first time you use it it's, like, wow, look at this thing go. This has a really long rod, so you want to make sure you're not putting this into your ankle. MIKE RIES: Well you want to shove it down far enough, though because there's a bow to the tibia, and so you want to get it a good amount. DAVID RABINSKY: We're solid. MIKE RIES: Looks like you are in good shape there. But you don't want to bow it. I try to line this up with the medial third of the tibial tubercle, the middle of the medial third. That gives us a nice alignment there. Let's have a mallet. I try to do one step at a time here, so that we can really get the alignment right where we want it. And we're going to take less tibia than we do for the BCS. MIKE RIES: So just walk us through how you're going to select your depth there. Do you use a stylus or eyeball it or-- DAVID RABINSKY: I use a stylus. I use a stylus here. And this is how we set it. We're going to set it for, it's usually eight or nine millimeters off of the lateral side. Which is less than what we've done with other designs. It's usually 10 or 11 off the good side. We're taking eight or nine. In this case, since we had an nice femoral cut, we're going to take nine off of the lateral side. Let's have the screwdriver. And then we're going to slide this down so it hits the bone. Once we set our depth-- MIKE RIES: And do you sort of put that on the hump of the lateral plateau? The lateral plateau is not exactly a flat surface. DAVID RABINSKY: Yeah. So you want to find your high point. MIKE RIES: Right. DAVID RABINSKY: And just be mindful when you lock this down. This has three degrees posterior slope built in. As you slide it closer to the tibia, you can increase your posterior slope inadvertently. So again, we're looking at our rotation. We're liking our alignment. I'm looking where this is pointing. It's pointing down to the second ray. So I have a couple of other ways to check, that I like what I'm doing. MIKE RIES: But the rotation's not critical here. It's just semi important. DAVID RABINSKY: Not critical, but it makes me feel good when I'm measuring it the same way every time. What we can do now is, we can disengage the tower. Screwdriver. And get the intramedullary guide out of the way. So this is nice. Just to, again, give another visual cue. It's hard to estimate posterior slope. But this looks like it's going to get us right down the center of the crest. So, again, verifying. And when we look, we are going to increase her tibial slope a little bit. So that's going to be good. And then we're going to pin this in position. Good. So we're very secure. We didn't change our slope. So that's good. Oscillating saw. So we've got to be careful of all the important structures here. [SAWING] MIKE RIES: So you're mostly protecting the collateral ligaments there. DAVID RABINSKY: We're protecting the medial collateral ligament with our hockey stick or our Z retractor. And we're going to leave this in place for the moment because it will allow us to change our cut if we need to. And you want to kind of spin it out this way from medial to lateral. MIKE RIES: Comes out the rest of the way. It doesn't always work. But usually. I can see you've got some good help there, which-- DAVID RABINSKY: Jeff has eaten his Wheaties this morning. Some days I won't cut all the way laterally, because it'll be-- you can't really see where you're going closer lateral. I want to save my proper TS, and you'll have a ridge of bone here that you need to take out with a rongeur. So now we can do two things. We can take this retractor out. We can check our cut. And, again, restoring this anatomic shape is what we're doing. You want your liner to look like what we're taking out. You want your tibia. So we have a, you know it's a concave medial tibia. It's a convex lateral tibia. It's a little thicker on one side than the other and it's asymmetric. This is what we want to reproduce. Here's our flexion extension spacer. MIKE RIES: Yep, your flexion spacer so you can see it's got a left and right. You put the thicker side one the lateral. DAVID RABINSKY: Right, so thicker side lateral, thinner side medial. MIKE RIES: So, that looks good. DAVID RABINSKY: And this gives us an idea. Is it 10 millimeter flexion space. That's our goal is a nine or 10 millimeter poly. And this tells us, hey, we've got good balance. We've got plenty of room for this 10 millimeter flexion space. So I think we're on the right track. We are going to try an extension block. MIKE RIES: You've got the extension block right next to you. DAVID RABINSKY: And, again, we're leaving our pins in because if we want to take a little bit more off the tibia or the femur, it's easy to do so. So if I put this 10 millimeter block in, we have full extension and we got good balance. MIKE RIES: OK. DAVID RABINSKY: That asymmetrical flexion extension block that's thicker laterally than medially, gives us a nice initial ballpark check. Like are we on the right track with our flexion gap. So now we know we're good. Let's take these pins out and then we go on to the femur. Then, again, this is very streamlined instrumentation. We're just taking our time here to show all the features. But a typical time on a standard total knee when you're not talking a lot, 45 minutes is a reasonable time without feeling like you're rushing through. MIKE RIES: Sure. DAVID RABINSKY: So now we have nice exposure of the femur. And let's take a look at our sizing block. So a couple of really neat features about this. We're going to put it right on to the femur and lock it in place with this pin here, with the headed pin. MIKE RIES: So now, what rotation are you starting with, relative to the posterior common line? Is that three degrees? DAVID RABINSKY: So, this is starting with zero. MIKE RIES: OK. DAVID RABINSKY: And we can dial this in as we need to. We typically, the standard is three degrees. But if you look at Whiteside's line, you find sometimes that you need more than three degrees. So let's first fix it to the distal femur. MIKE RIES: So you can see Whiteside's line and the epicondylar axis on that block? DAVID RABINSKY: Exactly. MIKE RIES: OK. DAVID RABINSKY: And I've marked Whiteside's line up here. And this my, this is the line I want to be perpendicular to that. And I definitely don't want to be internally rotated. I'm going to set this, and it looks like this person is one of those people that's right at three degrees. That matches up right with Whiteside's line where I drew it. When I look at the epicondylar axis, this is perpendicular to that anterior line. So the first thing we do is, we pin the block to the femur with a headed pin. We set our rotation. Now we're holding our rotation and we're locking it in position with this pin. Now the next step is, we have our feeler gauge. And we're going to take a Richer tractor. And this is why we took away what seemed like a lot of periosteum and synovium up here, but we really got to know what we're doing. And if we go back here, we're going to take our feeler gauge and feel-- This is the inter-lateral, the super lateral ridge is kind of the top of the cortex. MIKE RIES: You're putting that a little bit on the lateral side, not in the middle. DAVID RABINSKY: A little bit on the lateral side. DAVID RABINSKY: Definitely don't want a notch. And for this knee, if you're between sizes, so here, we're between a three and a four. We're going to upsize. And that's our goal. And this allows us to dial up and down. So, let's have the screwdriver. So, what I want to do is, I want to have it exactly on the size that I want. And we're going to loosen it up. And then dial it up and down. So if I dial this down, what this does is, it moves my holes from my cutting block posteriorly. So I have my finger right on the cortex. I'm exactly now on a four. Before, I was in the middle of three and four and it looks like I'm shifting it down just about a millimeter and a half. So, I'm going to lock that there. And say that that's where we want it to be. MIKE RIES: And you could do that on the other AP block, too. Move it up and down two millimeters. DAVID RABINSKY: Yeah. MIKE RIES: So, you can do it here or you can do it there. DAVID RABINSKY: So now all we're doing here is drilling these two holes. And that's going to be the holes for our cutting block. MIKE RIES: Got it. DAVID RABINSKY: So, with this, we're able to get our size exact. We're going to upsize if we're between sizes. And we're going to dial in our rotation. Let's pull this off. And again, we can double check. We can look at our pin holes. We can look at Whiteside's line and find that that's very appropriate amount of rotation. Now, the other degree of freedom we have, I'll show you after we get this block in place. And I can have the freedom now, I'm going to check, of course, of my angel wing. And I'm going to say, am I at risk here of notching? And I'm not at risk of notching. But if I did have a fear of notching, I can dial this block down or up, up to avoid notching. But if I want to get even closer to the anterior femur, I would dial it down. So, screwdriver. So we'll lock it down. We like where it is at zero. Because it matches what we just measured. And let's pin that in place. We don't want to overstuff this portion of the joint. We want our cut to be right on that anterior cortex. So we moved the four prosthesis down so it's even with the anterior cortex. The result of doing that is it's going to tighten our flexion gap a little bit. But that's good. We want a nice flexion gap for our cruciate-retaining knee. So, I always start my cut because I get nervous medially. [SAW BLADE] And we're right there, right on that anterior cortex. That's really nice. And then what we do is, we have a secondary cut here of a little extra cancel cut. [SAW BLADE] And then we have a more familiar looking shape here. And we're right on that anterior cortex there. It really is nice. And now that we can see better, I'm just going to clean up that cut. [SAWING It's going to be very nice there. OK. And then, these are labeled one through five. So there's five cuts here. We need our retractors. [SAWING] And then we have our last anterior chamfer cut. Let's have a Rich. [SAWING] I really like this kind of saw for this procedure. I can have control of the blade. The tip is oscillating only. And it feels very, very safe. You don't generate metallic debris by fighting your block. Let's have our slap hammer next. And, again, we're always checking along the way to make sure that what we're doing is making sense. And we're going to look and see, OK, we have enough external rotation. We have kind of a smaller lateral, posterior lateral, cut. Bigger posterior medial cut. That fits with our expectation. And, I think, when you check your flexion gap, this is something that's important to do, you want to look at a couple things. This posterior medial capsule is really tight. This is really binding us up. We have a little osteophyte back here that we're going to get rid of. But I also want to make sure I have released this capsule. Can I get my finger all the way back there? Which I can't. That 15 degree upslope kind of takes care of a lot of your osteophytes, but you still got to look for them back there. And make sure that that's not binding you up. We're going for a high function knee. We're going for someone who wants to go surfing, who wants to play tennis, we're going for the home run. So we have to really do this with that kind of eye. MIKE RIES: This laminar spreader here, really shows a nice way to kind of make sure your flexion gap is the appropriate tightness. DAVID RABINSKY: If you want to get very fancy, there are calibrated lamina spreaders that give you information. We're going to take out our lateral meniscus here, taking great care to avoid injury to our popliteus tendon, which we can see, right in the corner there. MIKE RIES: Do you generally not touch the PCL or do you wind up releasing it sometimes? DAVID RABINSKY: I leave the PCL pretty much alone. I think that I'm pretty good if I get my good cuts and everything is looking good. I don't really have to do much to do additional balancing of the PCL. So that feels like we're really clear back there. So we do an injection modeled after one of the hospitals in New York City. And this is a local anesthetic, some epinephrine, some antibiotic. And we go to the PCL, MCL, popliteus, pes. And then we infiltrate the quadricep. And it does seem to decrease their post-operative narcotic needs. MIKE RIES: So now you're using your symmetric flexion extension spacer because you've got rectangular gaps at this point. DAVID RABINSKY: Exactly. So this is our flexion gap, OK? And we're checking it, not at 90 but a little bit past 90. And that is-- MIKE RIES: That looks great. DAVID RABINSKY: That's not moving anywhere. We like that. And let's just make sure that we didn't change anything with our extension gap when we did our posterior capsular release. But if we get full extension with this, I think we're a winner with 10. We liked our flexion gap. We're checking our extension gap. And we have full extension here. We're rock solid. And let's see our long alignment rod. MIKE RIES: Yeah, that looks good from our view here. Looks like you're right down the center of the tibia. And you've got full extension we can see. DAVID RABINSKY: I think we're going to like it. So the next step now is to apply our femur. And a lot's been made of this. And we talk about in all the JOURNEY videos, but this is, again, an angle up. So you can't put it straight onto the femur. It's not possible. So you have to put it on like this. And then bring it up to get it to engage. So we're putting it on. You see how we're flexed. And then we extend it up. And it will lock into position almost as we bring it up. Can I have the hammer, please, mallet. So you're going to hit it up into position. And then we hit it home. And this engagement really causes those posterior condyles to force pressure onto the femur. So we have a grip on the femur now. This is not going to slide off. Now we're going to look medial lateral and see if we're centered the way we want to be centered. Generally we're going to be up close to the lateral aspect of the posterior notch. We're centered right here. And we're going to do one speed pin to lock it in place. MIKE RIES: Well, it looks like you've got it centered pretty nicely from here. MIKE RIES: Thank you. So what we're going to do is, we can drill our holes, our lug holes. So this is shaped with a fine point that's going to match the prosthesis. And then we can cut the notch. [SAWING] And we're taking out here a very modest amount of bone. Now we can put the rest of our femoral trial together. And this fits like a puzzle piece going top down. And we can take out this pin here. Slap hammer. [HAMMERING] And this is a young lady who's in her late '60s, who has fabulous bone quality. So we've trialed with our ten millimeter blocks. Let's see our tibia bone we measured and this gave us an idea that it was going to fit a three. Again, the asymmetric poly is the key to this design. I was a big believer in the BCS. And I loved the design of the BCS, the bicruciate stabilized knee. But I used to be a cruciate-retaining guy. And now that I have the anatomic features that I liked about the BCS and the cruciate-retaining design, I'm really happy to use this and go back to the PCL retention. And I think that there are a lot of benefits to PCL retention. One is that your anterior posterior translational force is really on the PCL, rather than on your post. So you not transmitting forces to your tibia. Of course, you're saving bone. That's a classic argument. But I think you're going to end up with a more natural feeling knee because of these anatomic designs with the dished medial tibia surface, the flat lateral surface, and the screw home mechanism, and the medial rotation in deep flexion. You get all these features and the cruciate-retaining design. So we're going to slide this in here. And the question is always, what if you're a little tight? In flexion, what do you do? MIKE RIES: It looks like you're forcing it a little more medially. But then once you've got in there, it finds its own home pretty nicely. DAVID RABINSKY: We're going to jiggle it into position. We'll take a look at it both ways. But I think that this is a chance to check our flexion extension gap. So, again, very stable. This is our best chance to do it. And we want to make a good coverage. It's an anatomic fitting tibia. So we want to make sure that we're centered. MIKE RIES: And now do you assess the AP stability there too? I mean you should have some shuck, but it looks like you've got a nice PCL there. DAVID RABINSKY: PCL is solid. And it really feels well balanced. MIKE RIES: I notice you doing that with the patella reduced, too. Which is probably much more accurate than with it subluxed. DAVID RABINSKY: So I think we're in good shape here. I'm just going to arrange it one more time. And then we'll mark it. I like that position. MIKE RIES: So, you got a three tibia and a four femur. Is that pretty typical? I find that combo happens quite a bit. DAVID RABINSKY: That's a common combo. And if you're off more than one size between your tibia and your femur, it's compatible. More than one, but usually it's within one size. MIKE RIES: Got it. DAVID RABINSKY: So we're just going to slide this patella out of the way and mark the other line. MIKE RIES: And it looks like you're also right on the medial third of the tibial tubercle there. We can see that pretty well. DAVID RABINSKY: And if we want to check and verify that we still got what we started with, this is-- we can drop our rod. MIKE RIES: Yep, you're definitely not internally rotated. Looks like you're right on there. And we can see, we got a good posterior slope. We've got our alignment right down the middle. So I think we're going to be very happy with that. MIKE RIES: Looks good. DAVID RABINSKY: Right on the second ray. OK. So we've marked that. Now we can bring the knee to extension. And do the free hand portion of the program and take care of our patella. And I find that I want these knees to be well balanced and very solid. We used to, in some designs, put in the knee a little loose, with the idea like, oh gosh, we've got to make sure it's plenty loose, so that they get their flexion and extension. But people who are going to use their knee for stuff other than just walking around, they want a knee that feels solid when they're stressing it and doing activities. Mid-flexion instability is a hard diagnosis to sort out. It can seem mysterious when it's presenting. This is kind of people who aren't super happy. So this lady here has a very, very thin patella. MIKE RIES: So you might take a little bit less off? DAVID RABINSKY: Yeah. MIKE RIES: So what are you, in the low '20s there? DAVID RABINSKY: 18. MIKE RIES: 18. That's very thin. DAVID RABINSKY: We got to get down to some good bone. The minimum thickness we're going to go with is 12, but probably 14 is where we're wanting to end up. I'm just going to be very careful and cut this sparingly. [SAWING] I like the feel of that. Let's measure what we ended up with. We're measuring. Basically 14. MIKE RIES: Oh, that's great. DAVID RABINSKY: Which is what we were looking for. MIKE RIES: Should be in good shape. DAVID RABINSKY: She has a round shaped patella now. MIKE RIES: So, bigger is better as long as it fits. Right? RI DAVID RABINSKY: Bigger is better, cheat her a little bit medially. And I think that a round patella for her is a good choice. Let's see our clamp. And Smith Nephew also has a oval patella option which works well. And a nice osteophyte over here. So we're going to get ride of this osteophyte too. Now we can check our tracking. And this is another reason I like this approach. We're saving so much of this extensor mechanism. We can really get very nice tracking. And I'm looking a retightened inflection just hanging here. We're looking at 135. She falls into full extension. She's very stable in extension. Flexion, we're going to tests a little bit more than 90. She's very stable here. And rock solid in mid flexion. So we like these implants. We'd like to open them. And then the only thing we have to do is, we're going to double check the tibia. And make sure that we like the size and punch it. So, when we go up to this point, let's see, this is a special tool that has a lot of uses. They call this the Swiss Army knife tool, or it looks kind of like a bottle opener. So we can pry off our tibia component here. We can take our speed pin out there with the drill. This piece fits in the hole. And you can't just pull the femur off. So we just rock it off like this. Then it comes right out like that. And now let's expose our tibia completely so we can really to triple check that we have nice coverage and we're not overhanging anywhere. And this is, they have right and left tibias. This is more common now. Smith Nephew is one of the early guys to do this. You're going to see that you have a larger distance medially, smaller laterally. And the tibias that were just one size, tend to overhang posterior laterally. And that bothers people. So this is a asymmetric tibia. And we can just go for optimum coverage. And we got some good cues about our rotation from our free floating. So when I look at this I'm trying to match it anterior to posterior. We're not overhanging medially. And laterally we're right on it. So let's see a pin. Mallet. [TAPPING] Good. And by having a narrower anterior posterior tibia, we're not going to have that posterioral overhang. We have excellent coverage medially. We're not overhanging. . No real osteophytes to go after. Let's have our drill. So, we're going to have a [TAPPING] four tibia. A three tibia, a four femur. Pretty common combination. We have our patella. 13 millimeters. Let's wash the knee out. MIKE RIES: We got a couple questions from our participants. What do you think is the ideal CR patient or what's your selection criteria for CR versus BCS. DAVID RABINSKY: I think a deformity less than 10 degrees. I think if you have more deformity, you're going to need more constraint. And then you're going to be looking at a PS design. I think if they have inflammatory arthritis, they're not a good candidate. PCL insufficiency. But basically anyone who has a good PCL and good bone, I think is a candidate. And age isn't as much of a factor as integrity of the ligament. So the other thing that's really nice as we look at our implants, and the materials are also important. Because we're looking at patients who are having higher functional demands. They're going to be putting their knees through many, many more cycles. So you need to have excellent wear characteristics. So when we're looking at this, we have our oxinium femur, which has a great track record, very, very abrasion resistant, very good wear characteristics. And we're coupling that with cross-linked polyethylene, which also is very durable. And I think that cruciate-retaining design is nice for this because you're avoiding any risk of post-impingement or fracture. You can mix? Please mix. The other thing that's nice about our tibia, in addition to being a asymmetric tibia, specific for side, this is a polished tibial surface. So there's reduced risk of any back side wear. An the other thing is, that you're going to have anterior posterior translation because it's a less constrained polyethylene design. This is going to accommodate any motion in that regard very easily. How's our cement, Trish? So we have a nice bone here to work with on the tibia. The cement is medium viscosity. It's not a high viscosity cement. And it does really interdigitate into the bone nicely. MIKE RIES: It looks like you're letting some go down into the hole? DAVID RABINSKY: I don't fret about it too much. I'm going to put a lot of cement on the back of my tibia. We have nice cement, We have cement all over our stem here. The cement really is like a grout. Our goal here is for the metal to rest on the bone and the cement to really connect that way and not be like a mantle, like we'd see in a total knee. So when we have a good cut, we're seeing the cement peel away. And we have really nice coverage of our tibia. Get a small rongeur, just kind of smooth that out. Now we can see everything we need to do. I'm not obsessive about a small incision. I think that we've really done well preserving the extensor mechanism. And we could still really see nicely everything we need to see. Let's go on to the femur. We're going to cement with an 11. So we felt that our fit was really good. But usually we'll cement with one millimeter or two millimeters more to get extra cement pressurization. MIKE RIES: Well, it's one of the nice things about having millimeter increments in the poly. Gives you that versatility. DAVID RABINSKY: I think it's really nice. I guess I keep going back to, the patients that we're doing our knees on today are really, they're coming in with different kind of complaints and different kind of plans. They're not saying, it's not the classic patient, where we wouldn't operate on someone unless they couldn't walk a block, and had pain at night and all this stuff. And now we're talking about people are saying. I can't jog. I can't play tennis. And, you know, we want to try to coach them through the standard nonoperative stuff. But, And, again, we're doing the flexion maneuver here, just making sure we're centered. Here we go. Now we're in the holes. Mallet. [TAPPING] MIKE RIES: Now you can't really see those two nubbins through the cement mantle, but I notice you were just trying to reproduce the same ML position that you had your trial in, so that the lugs go into the lug holes. Is that about right? DAVID RABINSKY: The nubbins, I can't see them through all the cement, but you can feel it kind of fall into it's position. MIKE RIES: Correct. I agree. DAVID RABINSKY: In softer bone, you might want to be more careful because you can create your own channel. You have a freer? You can put it almost where you want. But this is sitting right where we want it. MIKE RIES: And you were saying before, you had been trialing with the 10, but now you're going to do an 11 for the cement, cement trialing. DAVID RABINSKY: It gives us a free look at the 11 to see if that's something that we want to use. And like we were talking about before, I don't want to over stuff it. But we know that our flexion extension gaps are symmetric. And I want this knee to feel rock solid. This is our 11. Slides in pretty easily. We go into extension. I'm going to hold her in extension and get a little bit extra compression. MIKE RIES: Looks like you're still getting full extension, at least from here. DAVID RABINSKY: It came into extension pretty easily. If the flexion gap looks good as I expect it to do, I probably will go with this. I try to give just a little bit of axial load. And hold her in extension while the cement does its thing. So again we get another check. We see we have a nice flat patella cut. When our clamp sits right on the middle, it doesn't can't off to one side or the other. So again, we're always double checking quality. Now we're just doing what we all do, waiting for that cement to dry. So we just do our final check. We put this 11 in. And we're getting a very full extension. There's no question there. MIKE RIES: Looks like you've got, from where I'm standing, full extension. And you're dropping right down to 130 or so there. DAVID RABINSKY: That's pretty good flexion, just hanging. And she feels super stable. I don't think we need any more. It's interesting, that one millimeter gaps make a difference. I think that 10 would have been too little. I think the 11 is just right. Let's open that. And 12 might have been just a little too much. And let's just look in the back there. I got it. You don't need to, just suck it out the back. Is there a poly? So again, just to take a look at the poly, it looks just like our trial. Dished medially. Flat laterally. Wider laterally. Thinner medially. And it reproduces that three degree joint line that we're wanting to see. And I just want to make sure that I can slide it under. And this is just a simple pushing tool to lock it in. And there it is. That's it. And verifying, no soft tissue caught in there. And feed a little better. So, boom. We're happy. This is a good total knee. And we're going to wash it out and close her up. And I think that pretty much does it for our total knee demonstration. MIKE RIES: Well I just want to say thanks to Dr. Rabinsky and the OR team here at Wilcox Hospital. It's great to be in Kauai. And we have an opportunity for questions. So if anybody has anything they want to share with us or ask either one of us, please send the questions in. MIKE RIES: I'd like to welcome everyone to the question and answer session of the broadcast. We're utilizing some of the technology available to us. So it just requires you log on and submit questions. And we'll talk about them, sort of like a radio talk show, I guess. During the surgery-- And I want to thank David for doing a great job --we've had a few questions come in. I guess we'll start with those and see where we go. But we wanted people to participate and have this as an interactive session. So you're certainly welcome to send questions to join us. We've got one here which is, what is the lifespan of the JOURNEY cruciate-retaining knee? I guess I could start with that, just talk about the materials. The femoral component is oxinium. It's oxidized zirconium, so very durable, wear-resistant, ceramic finish on the component that's been used since the late 1990s and has a good clinical track record in a number of Smith & Nephew knees. And the tibial insert is highly cross-link polyethylene radiated at 7 1/2 meg rads, so a little bit less than what you have in hips to maintain greater strength. With in vitro testing that goes out 30 years, showing very little wear that's been quite encouraging that way. The JOURNEY 2 is still in use in clinical results going out that far. But I think you can extrapolate a lot of the in vitro data with the clinical experience of equivalent knees, in Genesis II and JOURNEY I having similar materials. The JOURNEY I had fairly normal kinematic pattern and stresses on the tibial component and thermal component fixation surface without loosening really being a problem. So I'm comfortable that it's going to be a durable implant. David, what do you tell your patients when that comes up? Because people want a well-functioning knee, but they don't go through this operation again. DAVID RABINSKY: I tell them that this is the best materials we have available, currently, for total knee or total hip. I use Zucks and EM and cross-linked poly for all my hips and knees. I think for the total knee, what I like about the cruciate-retaining design is that the anterior posterior stresses are transmitted by the native PCL from bone to bone. So you're not having stress on your post as you do with the posterior stabilized design. And I think that may lend a longer longevity to these higher demand, younger, active patients who get a CR knee. MIKE RIES: Well, just shifting gears, going back to the surgery, someone commented that there was no gapping at the 10 millimeter flexion spacer block, that spacer block you put in after you made the femoral and tibial cuts. So you're kind of sticking it in under the arthritic femoral condyles. How does that feel? How tight was it? And what are you kind of looking for with that? DAVID RABINSKY: For that initial flexion space check, I want it to be tight for a couple reasons. One is, I know that when I do my final clean out of the posterior knee, and I'm cleaning out that posterior capsule, I'm going to gain a little bit of flexion space. And if I have to choose between a tight flexion space and a loose flexion space, tighter is a little bit better for these cruciate-retaining knees. MIKE RIES: It looks like that's the first time you really checked the flexion space, that you're looking at it with the trial components. Do you do any fine tuning at that point if you need to? DAVID RABINSKY: I can fine tune it. And that's why I left the pins in the femur and in the tibia. So if I did my initial check of my flexion space, and I found it, for example, to be too loose, then I know that I'm going to need to increase my tibial space. And I can do that by cutting some distal femur. So that way my flexion extension spaces are balanced. So that's why we do that initial check. MIKE RIES: That was actually our next question. What would you do if that flexion gap was loose in comparison to the extension gap and you would put the AP block back on. I mean, the distal cutting block back on those distal femoral pins and take another two millimeters, and that should fix it. Is there any situation where you'd want to shift the femoral AP block posteriorly to fill up the flexion space? Or do you prefer to take two more millimeters off the distal femur? DAVID RABINSKY: We've talked about balancing flexion extension blocks, you and I, for a lot of years. And I think it's more straightforward if you think about, if you're increasing the thickness of your poly of your tibia, you're going to increase the space of tightness in your flexion and extension blocks. So the reason we take our distal femur is to accommodate the extra space we'll need on that polyethylene insert. If you shift that cutting block of the femur posteriorly, you risk notching the anterior femur. But if you have room, you can up-size the femur as well. I think that's a reasonable option in some cases. But it requires a little more complicated thinking. MIKE RIES: I think one area you can kind of fall into a little bit of a trap is if you've got a really heavyset patient and you have this massive thigh that's kind of squashing down on the flexion block at 90 degrees. And you think it's very tight. But it's just because the weight of the thigh is sort of pushing on the tibia in the flexed femur. And there, if you remove more distal femur and put in thicker insert, you find that the flexion space really wasn't too tight and now it's about right. So in the obese patient, I kind of have a low threshold to take off more distal femur to make sure I have good stability and flexion. DAVID RABINSKY: I agree. MIKE RIES: We've got a question about, the Noble Study, and some of the differences between hips and knees. But how does the JOURNEY II improve some of the endpoints of the Noble Study. That's the question. What do you see in your patients? DAVID RABINSKY: So in my patients, we talked about this. Maybe particular to Hawaii. But surfing is a good indicator of function of the knee. Because you have to go from a lying flat prone position and you have to hop up onto your feet very quickly. And you have to have high degree of knee flexion to bring your foot underneath you so you can get your stance on the surfboard. And that's been very difficult for people to do with traditional total knee designs. And with the JOURNEY II, I've seen people go back to regular surfing, which has been very, very impressive. Mark Snyder looked at a bunch of his patients and he presented this in Copenhagen last year and found that 88% of them had returned to sports at one year. And 200% had returned to work. So we're seeing with this JOURNEY II design, a real improvement in level of participation similar to what we're used to seeing what our total hips. MIKE RIES: Can you elaborate on that because what you said, I think, is very accurate. It's a level of participation, but do the rules change with JOURNEY about what you'd recommend for your patients regarding jogging, heavy lifting, singles tennis. In other words, are they achieving a higher level of impact or is it a greater number of patients achieving acceptable level of impact? DAVID RABINSKY: I don't think rules change. I think we're still talking about a total knee. And if you look at the consensus statements, high levels of high impact activity are going to cause increased loosening. So, as we talked about previously, I think jogging for exercise is probably not a great idea. Of course, cycling is a good idea. If you know how to ski or know how to surf and you have good muscle memory and good conditioning, returning to those activities is reasonable. And the rules don't change but more people are able to do what they want to do. MIKE RIES: Now there's several consensus statements now from the Knee Society, Occus, some of the European groups. And if you look hips, the Hip Society recommendations are pretty similar, to avoid the higher impact activities, but permit relatively unlimited repetitive lower impact activities. And a greater number of patients should be able to return to that level of sports, for the sports fiends, you know, lower to moderate level of impact. We've got a question about kinematics. How does JOURNEY CR provide normal kinematics without a cam-post? The JOURNEY I BCS had a cam-post, which is asymmetric and helps the femur externally during inflection, but also the tibial plateaus are asymmetric. The medial side is concave so the medial articulation is more of a ball and socket. The lateral plateau is flatter and slope posteriorly. And the external rotation is largely driven by the shape of the tibial plateaus. The same thing occurs in JOURNEY, so that it drives external rotation during knee flexion. Without a cam-post, there won't be as much rollback. Most of the recent literature in in vivo fluoroscopic data suggests that rotation is more important than rollback to get prolacted deep knee flexion and the desirable kinematic pattern. That also led to the development of JOURNEY II BCS from JOURNEY I BCS. It has essentially more rotation and less rollback or less early rollback. When I look at the JOURNEY CR patients, it does look like it rotates. And I think if you achieve that rotation with reasonable balance of the PCL, kinematic pattern, in terms of rollback may not achieve normal magnitudes. But the rotation probably is. And certainly that would be the direction to go and CR knees are getting us closer to a kinematically correct CR knee. David, do you see that? What you see during surgery? We don't have a magnifying glass but you could make some observations about it. DAVID RABINSKY: I don't think you need a magnifying glass to see that you're reproducing the anatomy with a concave medial surface and a flatter lateral surface. And then when you bring the knee into flexion during the operation, you can see rollback of the femur. You can see more exposure of that lateral tibial plateau. So you can see the rollback in action. And the patients are able to do the activities they want to do. That's what's most impressive, I think. Seeing the early flexion, people are getting greater than 90 degrees during the first two days. And when they come back, average flexion is 130. And that's a much better target than the traditional studies, where we were looking at average range of motion, 100 to 110 degrees. MIKE RIES: Well, just bringing this back to some of the questions about gap balancing. Traditionally we balance the knee at zero and 90 degrees. I think, we just sort of assume that in the middle, which is a lot of degrees of mid-flexion, the knee just sort of takes care of itself. My feeling is if the knee has a normal kinematic pattern, it'll be stable in the mid-flexion range and really get ligament isometry. Do you check for that? DAVID RABINSKY: I check for balance and extension, flexion, mid-flexion, and deep flexion. So, traditionally we tested the knee at full extension at zero and at 90 degrees real flexion, and would decide that it was good in the middle if it was good at those extremes. But now I check it also flexed all the way back and in mid-flexion to make sure it's all the way stable. And I think the balancing with your trial someplace gives you your final fine tuning of your soft tissues. MIKE RIES: I agree. I think that if you have that stability through mid-flexion and deep flexion, then the only way you really get that is if you've got a fairly normal kinematic pattern motion. And so it sort of confirms that that's probably what is going on. We had a question about how do you get anterior stability without an anterior cam? The JOURNEY BCS has an anterior cam post, where the anterior part of the PS post engages the anterior cam of the box, up to about 20 degrees. After that is in flex, that anterior post is uncovered, so it's not going to really provide any anterior stability. But in the CR knee, obviously you don't have that. You do have that fairly dish surface, though, on the medial side. And it's the medial kind of ball and socket articulation which provides the anterior stability in a well balanced knee. We got a question about PSI and patient specific instrumentation. When do you use it? Do you have indications, contraindications? What do you like about it or don't like? DAVID RABINSKY: Well I'm a big fan of patient specific instrumentation. That's more of our standard practice at Wilcox. And I think it definitely provides a greater degree of accuracy, streamlines the procedure. We open less trays. And I like the idea of being able to do the surgery before we enter the operating room. It really disciplines me to do much more precise templating and thoughtfulness before the surgery. Because you're asking a lot more in-depth questions than just laying the template on the radiograph. So I'm a big fan. I think it's very helpful when you have patients who have a valgus knee, for example, where you have a hypoplastic lateral femoral condyle and it's hard to get your femoral rotation correct. And there have been studies that show that patient specific instrumentation helps get that rotation on the femur correct. And we know that that's really, really important. MIKE RIES: Well, I agree with that. I think that's where you get the biggest bang for the buck is seeing rotation alignment. Because the MRI can see the epicondyles whereas we really can't. And you put your fingers on these slimy little nubbins of epicondyles. It's hard to identify them, particularly in a small incision. There is a lot of mixed literature, though. And the thing that kind of bothers me is that the literature lumps all the different PSI things together. And there's actually some differences between them. How do you sift through the literature and interpret the level of accuracy you can get with PSI, compared to conventional instrumentation? DAVID RABINSKY: Well there is-- we conducted a small study at our hospital, which was interesting. We made VISIONAIRE plans and templates for three patients, consecutive patients. And in one case, we did the cuts with the VISIONAIRE cutting blocks and proceeded with the surgical plan. And we measured our actual cuts versus the cuts that were planned on our VISIONAIRE plan. Then the next patient we used a computer navigation system. And we did again the same surgery and followed our VISIONAIRE plan. And then on the third one, we had our VISIONAIRE plan, but did the traditional instrumentation. And we're able, in all cases, to get our cuts within half a millimeter of our planned cuts. So I think you can achieve accuracy with any system that you choose to use. If I'm going to choose a patient specific instrumentation, I had experience with the CT based systems. And I didn't like that it had me remove osteophytes to get the blocks to seat. And I didn't think that it was as precise. I think the MRI, which measures the cartilage and allows you to sit right on the cartilage is going to be more precise. MIKE RIES: I'd agree with that. What about the sizing? The PSI gives you pretty accurate sizing. And the question is more, what are the sizing rules with JOURNEY II between the femur and the tibia. DAVID RABINSKY: So the sizing rules traditionally have been, if you're between sizes on the femur, you want to go down and downsize it. On the JOURNEY, our plan is to upsize it if we're between sizes. And you can do this shifting of the block, either with the cutting block itself or with your sizing guide and making your holes as you saw on the video. And the very low profile anterior flange allows us to feel comfortable upsizing a femur without overstuffing it. MIKE RIES: How about the rotational orientation? When you use that, you showed, really nicely, that sizing guide. I think that's what it's called. But it does more than sizing. It provides rotation, AP position and sizing. That is a medial pivot, as opposed to centrally pivoting or laterally pivoting. And those are the different ways you can adjust the rotation, each of which have some effect on the flexion gap space. Can you explain this kind of pivot thing? And just to make clear what we're talking about is, there are skids, or feet, that fit under the posterior condyles, one medially and one laterally. So when you rotate the block, and we say medial pivot, it means the medial foot is staying here and the lateral foot is moving posteriorly so there is going to be a air space between the lateral foot and the posterior lateral condyle. And you're actually shifting that part of the prosthesis or filling up the lateral space. What would a lateral pivot do or a central pivot? DAVID RABINSKY: A central pivot would do the opposite. It wouldn't fill up the space. The medial pivot just makes more sense, because you really want to shift that joint line, using that medial side as your basis of your rotation. MIKE RIES: And if you were concerned, maybe in a Valgus knee, is going to provide too much stuffing in the lateral, posterior lateral compartment, or more than you needed, we could shift it anteriorly. DAVID RABINSKY: Exactly. So you have the flexibility to change your rotation and anterior positioning. MIKE RIES: It's a really nice block, once you get the hang of it. And in addition, you can shift the AP block separately if you need to fine tune it further. So there are a lot of ways to really equalize the flexion extension gaps. Which I think is an improvement to the instrumentation that we have had before. What about that extra cut? There's the anterior cut, the posterior cut, the standard chamfer cuts, and this thing called a cord cut, which is a separate anterior bevel. And why is that there and what do you think of that cut? DAVID RABINSKY: Well there are two unusual cuts for the JOURNEY knee and they go together. If you think, and you look at the posterior cuts, they're 15 degree up slope. And when you put on the JOURNEY component, you engage the posterior condyles and then roll the femur on to the top like this. And that cord cut makes space for the JOURNEY to come up and engage with the top part of the femur. And the reasons for those cuts are to enable more stable initial fixation of the prosthesis, particularly in deep flexion. So in the 15 degree upslope cut, when the knee is in deep flexion, there is a direct compression on to that posterior condyle. And rather than if it was a flat cut in deep flexion, the tibia would act to lever the femur off. And a lot of deep flexion designs achieve that by cutting a huge amount of posterior femur. And you had talked earlier about the loosening issues. MIKE RIES: There has been literature with high flexed knees, showing abnormally high loosening rate of the femoral component with some other designs where the anterior and posterior cuts are parallel. And the theory there is that in deep flexion in patients, particularly some of the Asian populations, where patients can consistently achieve very high flexion, 130 degrees or even more, that at that degree of flexion, the tibial component is actually pulling, pushing the femoral component off the end of the femur, sort of making it pop off. So this cement is under tension and that would be the reason for the high loosening rate. With JOURNEY I, which had a good clinical experience, in terms of stability, there really hasn't been any loosening. And that has the same angle of posterior cut. And I am convinced that that not only removes less bone and kind of the things we were talking about, when you put the trial on and you try to yank it off, you can't get it to come off if you apply axial traction or go to grips the femur. So that's, I believe, an advantage in terms of minimizing risk of loosening. We have another question. This is a little bit redundant with the activities we talked about, but I think it's still a good point, which is, will you let your patients return to activities like jogging or other activities? What do you tell them about the upper limit or certain things that you say no to. DAVID RABINSKY: I think repetitive impact loading is going to cause any total knee to loosen. . I use a lot of car analogies. And I tell them if you get new tires on your truck and you drive on the highway at reasonable speeds, they're going to last the 40,000 or 50,000 miles that they're warranted to last. If you drive it on rough roads and dirt roads and off roads, they're not going to last as long. And then you have to deal with the consequences of that. And I would encourage people already expert or knowledgeable and activity to do it safely and sanely. But, for example, we talked about jogging for exercise would be an example of something that would definitely cause the knee to loosen earlier. MIKE RIES: And we've got a question about how many, what percent of your patients you are doing CR versus BCS. I think this is a good question because it relates to the indications for the two, which we probably haven't talked about a lot. So in terms of deform-- well, you know, how many of your patients get CR and tell us a little bit about your practice and how much deformity and stuff you have and maybe I could do the same. DAVID RABINSKY: I think that my practice has the broad spectrum. There are a lot of young very active patients with knee arthritis on Kauai. So if someone is young and active, and has a good PCL, and does not have a lot of deformity, they're a great candidate for the CR knee. And I'd say that probably is 70% to 75% of my practice. But the more deformity they have, or if they have an inflammatory arthritis, then a PS design is more appropriate. And then BCSs might go, too. MIKE RIES: I'm similar that way. I've been using the CR in my less deformed knees. And also the younger patients. I do like the idea preserving PCL and not removing the box in the younger patient without much deformity. For me, it's quite a bit lower. It may be the difference in my practice, probably about 20% percent or so. That's starting to increase as I get more comfortable with CR. But I also started off as a CR guy years ago. And at that time the mentality was if you're in between sizes with the CR, and we were all pretty much using anterior referencing, you use the smaller size to loosen the flexion space to make sure they got adequate motion. And they got great motion. But unbeknownst to us they also got flexion instability because you have this loose flexion space. And that came out when the fluoroscopic studies showed that paradoxical motion and everything like that. And that kind of led me to be more of a PS guy. So when, I think, you're one of these people that shifts one to the other, shifting back is slow. But I've been coming back to it and had started using it my less deformed knees. I think my practice is such that I've still got a fair amount of fairly deformed knees. I think the ideal patient is the young, active patient without a great deal deformity. But I use deformity as my primary indication for when to go to PS. But if I have to start really releasing ligaments, I'll go to the BCS. DAVID RABINSKY: I think that's reasonable. And I think the CR knee really requires excellent gap balancing and excellent ligament balancing to achieve a stable and very functional knee. And I think the kinematic advantages are helpful, even in an older population for the BCS and the CR knee. If the quadriceps, which is already weakened by arthritis, has to work a little less hard to get the motion back I think you're doing them a big favor. And both knees accomplish that. MIKE RIES: We've got a question about metal sensitivity. It's kind of a two part question. And I'd say one is, why use JOURNEY for metal sensitivity? It doesn't have nickel in it. So for a nickel sensitive patient, you've got oxinium, which is oxidized zirconium. It's kind of a metal substrate. It's like titanium. Doesn't have cobalt or chromium. The base plate is titanium. And then the rest is plastic and cement. So you can use it in a nickel sensitive patient. It's a good indication for it. And I think there's very good support for that situation. The second part of the question, though, is, some surgeons are using other knee replacements have symmetric condyles and they're sort of used to their way of doing it and their way of looseness. And when they've used JOURNEY, they notice it feels tighter, it feels more snug and more stable. So the question is, how tight do you put it in. What advice to give somebody if they call you on the phone and say, how tight is right. Or is it patient specific? DAVID RABINSKY: Well, I think with the JOURNEY II, you want have well balanced flexion extension gaps that are tight. And you need to be able to achieve full extension with the leg hanging, without it bouncing. And you want to let it fall and have it get to 135. I think if you can do that, you want a tight knee. I mean, you think about how would you like your knee to feel if you had a total knee. I'd want mine to be really stable and really solid, but achieve a full range of motion. So I think it's reasonable to have it tight. As far as the materials question, there's been studies that suggest that their patients have good looking x-rays but sore knees. And they have a higher rate of metal sensitivity than we would see the general population. So there are probably some people who can wear earrings and wear sunglasses and wear watches, who have a low degree of metal sensitivity or maybe even developmental sensitivity after they get a total joint. So in my practice, every patient gets titanium, oxinium, cross-link poly, total hip, total knee. I just want to rule that out as an issue for a problem down the road. MIKE RIES: Well, it certainly simplifies it. I do think metal sensitivity is a real issue. It's just, we don't have a good test for it. It's a fairly nebulous issue but I have concerns about people that say it simply doesn't exist. In terms of the tightness, I think JOURNEY is a more stable knee and ideally you want a stable knee throughout the arc of motion with good physiologic motion. If you have to put in excessively loose to get motion, then I don't think that's where we want to go. That's kind of what I was saying about the history of cruciate-retaining knees and putting it loose in flexion. I do think you individualize a little bit. If it's a female patient, their ligaments stretch little bit more. They're a little spongier. So a thin, scrawny female patient, I would put in maybe a little looser or not have to manhandle the leg as much to get it to gap. The younger male patient, I think their ligaments are more like ridged cords and you have to put them in fairly tight. And they're going to beat on it more anyway. So they're the ones with the greatest risk for instability. DAVID RABINSKY: And then there's the valgus and varus knees have a little bit different personality too. Varus knees tend to be a little tighter. So you might err a little bit looser on those guys. The valgus guys tend to be a little bit looser. You want to tighten those guys up a bit more. But, again, most of the trouble, I think, is when you end up putting in a thick poly to balance your flexion gap and then you can't get full extension. And then you downsize your poly and then you get your full extension back. But then you're loose in flexion. And then you have a knee that's unstable. So I think the balance is what's going to keep you out of trouble. MIKE RIES: A lot of the revisions I do are for instability. I think there are various patterns of instability. But my sense is that, you know, all knees are a little bit unstable because they're all ACL deficient knees. So we take this normal knee, remove the ACL and expect the prosthesis to provide that anterior cruciate stability or normal kinematics. And if you put the knee in loose inflection, you're going to get a little more shucking between the femur and the tibia, which then leads to the soft tissue inflammation. You know, the guy that goes out and has to take a bunch of Advil after 18 holes. Or his knee swells up and they complain and bitch about it. That that's really leads to the level of dissatisfaction in knee replacement patients. If it's an inactive patient, older person just walking to the mailbox and back everyday, they're never going to experience that. But our patients have pretty high expectations now. And so I think to keep up with it, this is a good approach. We've got a question about post op management and using CPM or a mobilizer. Are you using CPM at all? And how long are your patients staying in the hospital? What do you do with them in post op? DAVID RABINSKY: Well, I think it starts pre op, actually. Every patient, before they get surgery, goes to a pre operative class to teach them exercised and orient them to the process. And we tell them, you're not going to spend more than two nights in the hospital. That's our expectation, is go home post op day two. And we get them moving right away. We don't use an immobilizer. We don't use a CPM. Patients are able to do straight leg raise post op day one because of the many mini midvasus or sub vasus approach. And they are up and going. So I think there's not really a role for CPM any more. And the other thing is, I tell the patient if they can, to buy or rent a stationary bicycle and have it in their home and they are their therapist. So I think by partnering with the patient, involving them in their care, it obviates the need for some of these accessories. MIKE RIES: I like the bicycle. I think in the past, we got a little too reliant on the CPM. But it's not very physiologic motion or activity on the bicycle, even they kind of rock back and forth before they can make a full revolution. It's a better way to go. And I tell them, put the seat up and lift one cheek up, whatever you have to to finally get around and make a full revolution. Are you using anything special for post op pain management to get them out in two days? Are you using the cocktails or blocks? DAVID RABINSKY: You saw on the video, I definitely use the rock star injection is what they call it. It's related to the one that was originated at a hospital for joint disease. But it contains a narcotic, an antibiotic, some epinephrine, and some local. And we inject systematically the PCL, the MCL, the popliteus, the pes, anserine, insertion, as well as the quadriceps muscle. And we think that helps all lot with the post operative pain. We start preoperatively with the anti-inflammatory and oral analgesia, as well as intravenous analgesia in the operating room. And then post operatively, around the clock, oral anti-inflammatories, maximizing their Tylenol dosage in a safe range, and then giving them narcotics only for breakthrough. But most patients, again, it's also preoperative counseling, telling them that it's not realistic to expect a pain free experience. And if they're kind of oriented to the idea that they are going to have some discomfort and really have to work hard for the first four to six weeks after surgery, they get excited about pushing through the program. MIKE RIES: OK. We're trying to keep up with things. We've got a little bit complicated one, but I'll read it to you. It says, has the elimination of paradoxical rollback and quads inhibition gate been proven in the JOURNEY II? JOURNEY II is newer than JOURNEY I. JOURNEY I has had a very extensive series of studies done by many independent investigators using fluoroscopic kinematic studies that show a normal kinematic patter of motion in comparison to others, meaning rollback in rotation that's similar, and EMG studies that also indicate pretty normal quadriceps and hamstrings function, I believe. So the answer to that, by JOURNEY I was, yes. There was a little bit of spare baggage with JOURNEY, in that it rolled back early, rather than late. And JOURNEY II has been developed to retain the same rotation, with less rollback, so that the kinematic aspects of it are still retained. The studies aren't there yet, though, to support the same statements, I would say, with JOURNEY II compared to JOURNEY I. But I think you can extrapolate a lot from the JOURNEY I experience. And changes have been pretty subtle from one to the other. So I wouldn't expect anything different with JOURNEY II. And I think the achievement of the clinical and functional results have been much more reproducible. The second part of the question is, is it the shape the poly that's driving the motion and possible that this would have an adverse effect on the mechanical properties of highly cross-link polyethylene? The poly is overall shaped pretty similar between JOURNEY I and JOURNEY II. The medial side is kind of a ball and socket. The lateral side is flatter and shaped, sloped posteriorly. But if you look at the cross section of the lateral condyle, it's dished in a medial to lateral dimension. Which means that when the femoral condyle contacts the lateral plateau, you still get line contact. There aren't any knees out there that give you larger contact area than a line, other than a completely conforming mobile bearing ball and socket. So the contact area and wear properties, wear testing and clinical experience, so far over a number of years with JOURNEY I has been very good. Wear or defamation, fracture to poly, or things like that, have really not occurred. I think that's a theoretical risk, in terms of stressing the mechanical properties or limits of highly cross-linked polyethylene. The material for JOURNEY II is is 7.5 mega rads, which is less than in hips, in an effort to maintain the durability of it. And I don't see that issue with the conformity as really pushing the limits of the mechanical properties. Ultimately time will tell. But there's been a very favorable growing experience with cross-linked poly in knees that builds on hips, so it's something that I'm pretty confident using. Do you have this discussion with your patients about the materials and obviously the durability comes up. People ask how long is it going to last and what do you tell them? DAVID RABINSKY: Well, I tell them that in the simulator, we've shown that the polyethylene and oxinium combination will last about 45 million cycles with very minimal wear. And in most cases that is equivalent to about 30 years of wear. But I think it's hard to promise someone how long their knee's going to last, as much as they want you to tell them this. And I tell them that, for the average person, you can expect excellent wear properties. And 30 years is definitely a reasonable and achievable goal. And you could certainly go beyond that. But if someone is 300 pounds and they're jogging and running heavy equipment every day, I think it's unrealistic to expect that much. I think, regarding the knee design, like we had touched on earlier, I think the cross-linked poly is going to be protected to some degree. Because your anterior posterior stressors are going to be controlled by the PCL, bone to bone. So poly and the tibia, they aren't seeing those stresses as directly. So I think that the CR design may have even better wear characteristics than the BCS. But we'll have to see. MIKE RIES: Well, David, it looks like we kind of reached last call here, for questions. And I think everybody's happy. How things out there? And I'm just going to ask you to wrap it up and let us know how the weather is in Hawaii. DAVID RABINSKY: Well the weather is another sunny day, 80 degrees. And I would say, you guys are all welcome to visit. We're a VSP site, so ask your rep to come on down to visit us here at Wilcox. We'd love to have you. And, as we say in Hawaii, aloha and a hui ho. MIKE RIES: Thank you. DAVID RABINSKY: Thanks Mike.