All right, we're here with Phil Wilson from Scottish Rite in Dallas, and he is going to give us his pearls on osteochondral allograft preparation and transplantation. Yeah, thanks, Henry. So you know, I think osteochondral allograft is a very nice option when we have osteochondral disease, much like our OCDs, sometimes with our traumatic lesions. But the nice thing about an osteochondral graft is it can replace that column of physiologic bone from hyaline cartilage to tide mark to subchondral bone and then cancellous bone. And so it's a very nice way to replace. Remember, the things to think about principally is we're going to get creeping substitution because our allograft bone has to be replaced over time by the recipient. So we've got to get a solid graft in, but we also want to minimize the amount of bone because the more bone and the more depth of bone, the more creeping substitution required. So whether we're condylar in location, trochlear, or patellar in location, our goal is to be able to graft our lesion, but minimize the depth of cancellous bone involvement because more bone means longer incorporation. There are a couple of sets. Many of the manufacturers have different sets. Some of them will give us a round dowel option like this. Others, there's an elongated option where we can put in more of an oval-shaped graft in. It's a little bit more of a complex jig system. There are jigs set up for the trochlear anatomy and the patellar anatomy. You know, in our population, in our kids, oftentimes we have dysplasia of the patellar or trochlea that created or was coexistent with that lesion. So sometimes the autograft or the jigs that are for normal anatomy may not extrapolate to our kids as much for patellar and trochlear. So I find sometimes we'll even use a trochlear donor for a patellar lesion just to be able to get that complex anatomy and then extrapolate it to patella. Sometimes it's patella to patella if we have more normal anatomy. And then the other thing I would tell you in terms of ordering our grafts, our graft suppliers will allow us to get a condyle or an entire trochlea. You can certainly order an entire distal femur or you can order a patella. So being mindful of where your lesion is, it will help you kind of order your graft. Generally sizing our graft, in our kids, most of the time with OCDs, our radius of curvature has flattened a little bit. So we send imaging and they give us a line-to-line fit or a close-to-line-to-line fit of our donor to our patient. However, we may want to upsize just a little bit in our TW, which is our total width, our TL, which is our total length. Because if we upsize that by a few millimeters, it may allow us to have a bigger radius of curvature to match any dysplasia that's occurred in our patient. Because that dysplasia is actually not going to be accounted for. The flattening of the radius of curvature in an OCD is not accounted for when you just get the standard graft measurements. So a slightly larger graft is better than a slightly smaller graft. Ordering anatomy-to-anatomy if you can, but if you have dysplasia, sometimes ordering a whole femur or a trochlea, in other words, to work on a patella to have multiple options. So what we've got here, we've got a lateral femoral condyle lesion in this left knee. This is kind of an involuted lesion of an OCD that we've lost a little bit of chondral surface on. So the first thing we want to do is get our guide, and we have a donor and a recipient side of our guide. Those are sized differently to make up for the kerf of the harvester. And so we want to make sure we're using our recipient. And then what I'll do is put a pen mark, you can see we've put a little pen mark on the edge of this, and then that allows us to come and find our best fit on our lesion. So we've already done that, and we've found that a 20 millimeter graft will fit on our lesion. And then what we do is we kind of float our hand a little bit to find the best fit on the lesion. We can kind of check to see that our pen mark, then when we extrapolate the pen mark, we can see that we're going to harvest around our whole lesion. So we've decided that 20 is going to be what we'd use. So the first step we're going to do is to work on the patient, on the recipient, before we work with our donor. Now, one last word. Before your patient goes to sleep for an osteochondral allograft, you as the surgeon should lay eyes on your graft and make sure that the laterality and that the graft is what you think it is. That is incumbent on us as a surgeon before our patient goes to sleep to make sure the graft is what we think it is. All right, so now we've done all that. We've got our patient. We've done a medial parapatellar arthrotomy. We've averted the patella. We've got the knee flexed to about 115 degrees of flexion to allow us access to this central posterior condylar defect. So next we're going to use a guide pin. We've sized our lesion to a 20. We're making sure we have the recipient side, which is the smaller side, and then we're going to use our guide pin. Once we've got, we're floating loosely to make sure that we're centered on that lesion, and then we're going to use our guide pin, which locks in the trajectory of our tools that are going to use to prepare that recipient site. So after we do that, the next thing we can do is we can come in with a scoring reamer. So the scoring reamer, the idea of this is that we're going to score the native cartilage so that before we hit it with a paddle reamer and cause either heat necrosis on the margin of the cartilage or hit it with the paddle reamer that can extend a cartilage margin, we want to use this scoring reamer and we can pop through that surface cartilage and hyaline cartilage to make a nice perpendicular starting point for our reamer where the cartilage is, we have a mallet, where the cartilage then already has been prepared to get that reamer. So we can just really push our scoring reamer in, remember our depth of cartilage down here is generally somewhere between two to three and a half millimeters thick. All right, so we've got our scoring reamer and you can see we've prepared our edges of our lesion and so now we're ready to harvest or to prepare the recipient socket. So what we do, all of these sets, regardless of manufacturer, have sizing on them. So we've selected a 20, so every one of our instruments we need to double check that we've got a 20 available to use. This is a little bit loose in there, should it be spinning like that? So again, at this point, we're going to check our surface, make sure that we are happy that our scoring reamer has given us a nice cut all the way around and we're centered on our defect, we're centered on our lesion. The other thing Dr. Ellis and I talk about a lot is these lesions that encroach on the edge of the notch. And in our population for medial femoral condylar OCDs in the zone of propensity, they're often right here, right up against the PCL. And so if we can, we try to leave a little margin of bone at the edge of the notch between our lesion. But sometimes we end up with a lesion that goes into the notch there a little bit. And sometimes that's a little bit less stable. So what we're going to do now is get this up to speed. I usually use it on drill. And so we're going to get it up to speed. We're going to come back and forth and make sure that we're collinear on our wire and that we're not torquing our wire one way or the other. And then once we hit this, we want to go through that cartilage, you can see our scoring reamer got us ready to go through the cartilage. And then as we go through the subchondral bone, we want to go to a depth that allows us to get through our lesion, but we want to minimally harvest bone so that we minimally remove bone so that we don't have as much bone that we have to get replaced by creeping substitution. So we have laser marks on our paddle reamer. We've gone to a depth roughly of about seven millimeters. And so over time, we've seen the benefit of going more and more shallow. And so what you can see here on this arthroscopic view is what you can see is we've got good cancellous bone. We've got cancellous bone on the walls of this lesion. If this was an OCD, we'd want to make sure that we had at least 50% of our lesion depth harvested and then we could bone graft any cyst. But rather than drilling down and going deep to a big cavitary lesion, we want to prepare to the minimum depth that we can and then bone graft any deep cysts. Again, all we need is about three millimeters of cancellous bone on the walls to get nice graft incorporation. Again, we've probably got a five to seven millimeter depth here. So I think that's absolutely perfect. And then we have, so next, again, size specific instrumentation. This is a 20 millimeter dilator. And what we can do with our dilator is bring it in and we can either use a mallet or the hand slap hammer and come in and you can size your depth off of this. But also what we're doing is making sure that we've got that dilated and prepared in all margins. The other thing I would tell you is there's a tendency when we all first start doing this to worry that our socket is going to be too big and that our graft fit is going to be loose. That is seldom a problem. And so a lot of times when we get this dilator on, we actually want to bring it and cant it just a little bit in all directions and really dilate that socket because our goal is to get this graft in with a press fit and have to impact our articular cartilage on our donor a minimal amount. So once we get that in and get it prepared, again, we want to really kind of go and dilate that socket. So now we're ready to come and take our pin out. Let's have our pin driver back. Got it? And I'm just going to inspect the base of this just a little bit. We got a little bit of articular cartilage. So will you change your depth based on your MRI? Yeah. We try to have a good idea of the depth because you can have lesions that are greater than seven or eight. That's right. In terms of the fibrous bone. So sometimes you need to go eight, nine, ten. I'm not talking about the cysts. That's right. So I think a good rule of thumb, I think the MRI is our subchondral roadmap and we can plan on our depth or our expected depth and then take it to say 50 to 70 percent of our entire base is healthy cancellous bone. And then if we have spots that we need to curette out and bone graft and we can take bone graft right here from the distal femur, get some loose cancellous graft, pack it in, use a tamp so that we don't want to go to 12 millimeters all over if we only need eight millimeters and then can go on a couple of cysts deeper. But I completely agree the MRI is our map. So now what we'll do is we're going to measure our depth in all quadrants. So we have a little ruler here that we can measure. And so on the north, we say kind of break it into north, south, east, and west quadrants. So north, and our assistants are going to mark this for us or note it, north is eight millimeters, east is eight millimeters, west is also eight millimeters, and south is also eight millimeters. So we have a nice sort of eight millimeter in all quadrants. We may need to adjust that a little bit if we impact one more time. But now we kind of have our base prepared. At this point, we'll put a wet sponge in, we'll extend the knee and put the patella on top, let everything take a break, and now we're going to work down on our donor graft. So our donor graft, we've already put in a jig. So we have a preparation or a workstation where we can get a firm grip on our donor graft, and then what we use is the backside of our size-specific dowel has a donor side. And we use that donor side to come in to the jig. Each jig has a size-specific collar that fits our sizer. So we put that collar in the jig, and then this jig has multiple degrees of freedom. And so we first let this sizer float. And I'll get down and get eye level. Sometimes we can use the scope to look right down on it, and we can really visualize exactly our fit and make sure that our gaps are even, if we have any gaps, and make sure that it looks like that we are going to be completely perpendicular with our starting point to the radius of curvature. So we like our position, and again, what we did was we held this, we opened this, we get multiple degrees of freedom, and then you have the little pin that we use to tighten that. So then what we can do is once we get everything fit, we can hold all this in place and kind of put it tight to hold our final angle after we've adjusted all that. So now we're ready to harvest, and we know we need an 8mm graft. So what we'll do is come in, and again, our jig is going to assist us with maintaining a radius of curvature, but we want to make sure that we're completely collinear. We've got something that's a little bit bigger maybe. Let's see, I don't want to spin this by hand. Do you have a mallet? Let me just see if it'll pass. Okay. Let's see if we can get that to work. So we're going to bring this down, and we can double-check one more time that we feel like our angle of approach is good. The other thing that we did was we used landmarks on the knee, like the surface of the notch, the surface of the sulcus terminalis, to determine the zone-specific location of our donor. So not only do we look at the radius of curvature, we're taking it from that zone-specific spot. So now what we're going to do is we're going to get up to speed, and then we're just going to go straight in, and here we'll often do some water irrigation so that we cool this while we harvest it, and we're going to go down. In this case, we're going to go down to a healthy depth of about 15 to 20 millimeters. So we're about 18 millimeters. So one technique is you can drill all the way through, and there's a tamping rod that will allow you to tamp your graft out of the whole donor block. The other way is I will go about twice as deep as I need to, and then I'll come back out and then bring a sagittal saw in and harvest our graft with a sagittal saw. And so the way we do that is we just make sure that our sagittal saw depth is going to be deep enough to come across the base of our lesion. Do you have a marking pen by chance? Thank you. And so we're going to come in here and say we went about 18 millimeters below. So if we bring our sagittal saw in right here, that's going to free our graft up. Yeah, and so before we harvest, we've got a little dot right here where it's going to delineate north on our graft. So that way, not only are we zone-specific and radius-of-curvature specific, but we've also oriented our graft in the right direction for those contours. So now we're going to come in and harvest that block. Dr. Ellis is holding the surface of the donor plug so it doesn't pop out once we get free. And usually he can feel it shift when we're all the way through. I think it did, didn't it? I think it did. Okay. And so now what we'll do, do you have a freer? So usually we'll use a freer elevator or another small instrument to just come in and pop this graft up. We just need a freer if we have one. We'll get our graft popped up a little bit there in pickups now. Perfect. Okay, so now we've got our north delineated on our graft, we can inspect our cartilage, we can inspect our cancellous bones, so we're really happy with our graft. So the next thing we can do is take our measuring stick back, see Henry if this thing still marks, and we want to go about eight millimeters around the entirety of our graft. So we'll come in here and we'll go eight there, now we'll go west, and again we've got ten, nine, eight there. We're going to plan to cut our purple out because we're marking at the base of that, ten, nine, eight there. Okay, and ten, nine, eight there. Good. Okay, so now, let me see that marking pin one more time if you don't mind, Henry. So now we're going to just kind of extrapolate our lines just a little bit, and we're going to double check our depth in a couple locations to make sure that our measurements are correct. Cut out our purple line. Perfect. Okay, so then we can manage our graft to cut with our sagittal saw with this crab clamp, and what we want to do is sometimes there's some obliquity to this and we can orient, so if we've got say an eight depth on one side and a five depth on the other, sometimes we really have to orient or change our graft, but in this position, or in this particular case, I should say the graft is pretty uniform in its depth, and so we just want to set this up so that our saw is going to cut out our marks because that's the way we kind of marked our measuring, so that's going to, our saw kerf is going to take our purple out all the way around, and so then we'll clamp this down. What I would generally do here is I will put a bunch of irrigation on some blue surgical towels or something and set this down on a surface, and then generally bringing your saw in here and laying your saw flat and using that saw as your chalk block, and you don't want to trust your clamp alone. You want to continue to grasp your clamp firmly as you cut that. I would recommend, we kind of think, oh I want a small blade because I'm going to do some fine work. Really a bigger blade will kind of go across this a little bit better. A smaller diameter or a smaller width blade tends to kind of get lost and wander a little bit more, so a bigger blade, even though you think, you know, more precision with something small, the bigger blade is actually better for this. So at this point, we can irrigate and kind of clean up our graft. There are a couple of studies that say that pulse lavage irrigation, just like we think about in trauma, the pulse lavage irrigation does not give us any benefit in reducing any remaining blood elements from our graft. Remember, bone and cartilage is immune privileged, and so it's only the soft tissue cells that remain in this graft that are immunogenic, and so this has been washed and lavaged, but remember it's not sterilized, and so if there are a little bit of blood elements there, that may be a cause for delayed incorporation or a little inflammatory response, and not true rejection, but just slow incorporation or incomplete incorporation, and so we want to lavage this, but lavaging maybe with a low pressure lavage. Some people still use pulse lavage. I don't think that's necessarily a bad thing, but the question is, are we driving some of the blood elements deeper into the graft? Another question is whether we should augment our graft with something biologic, like should we put bone marrow aspirate concentrate or something in our graft? There's been one study looking at that. It may not be powered as much as we'd like, but it doesn't show necessarily that putting bone marrow aspirate concentrate increases incorporation of our graft, so now we're just going to come back and check our depth and see how we did, and so we can check and make sure that we've got the depths that we're looking for all the way around at all quadrants. Eight everywhere. Our north depth may be a little bit shallow in one little spot, but I think everything's pretty close. We've got one little corner here that may be a little shallow, so if we need to, we could take a shim. We can take a shim either from our previous graft that we used, or we can take a autograft shim. I don't think we need to in this particular instance. Now what we're going to do is we're going to use some Vicryl. So again, if we think it's too shallow, if we think our donor plug is too shallow in places, we may want to put a shim in place, but if it doesn't fit, if it's either too shallow or too deep, the manufacturers make a little set screw, like a little wood screw that we can put in to pop our graft out. What we've found is that that doesn't really extract the graft as nicely as we'd like, and so what Dr. Ellis and I have taken to doing is using Vicryl and putting Vicryl across the base of the recipient site, and it kind of acts like little parachute strings, and it allows us to extract the graft if we need to, but if we're happy with our graft, we can cut and just pull out the residual Vicryl, and so this technique has allowed us to really remove and fine-tune our grafts much better than the set screw method, and so we get our little Vicryl crosshairs in there, and then we're going to orient our graft. Sometimes we'll do this with a little clamp or a hemostat. Most of the time I'll use some fine pickups, actually, yeah, to just kind of orient. This is when we'll get a little kidney basin and put our kidney basin underneath so our graft doesn't pop out and roll on the floor. If your graft does pop out and roll on the floor, just like our soft tissue grafts, multiple lavages have been shown to still be effective using a Hibiclens lavage, and so I would kind of counsel the family that that's a reasonable option if the graft does hit the floor. So then we're going to line things up. We want to get our graft started really at the appropriate angle and depth all the way around. If we get our graft started in one quadrant and it starts down unevenly, it's hard to get our graft squared back up, so we really want to get our graft started so that it's just barely in contact all the way around, and then what we want to try to do is, as much as we can, we just want to lightly push that graft in place. If we have to tamp it, we will, but if we can put it in with just thumb or finger pressure, even better. The other thing that I'll often do at this point, can we cut our co-band? The other thing that I'll often do at this point is once we get it nearly seated, what we can do is use the opposing articular surface wherever we are to actually reduce that graft, and that may be a little bit less stressful on the graft than hitting with a mallet. So we can get it here and then use the tibia with flexion extension and a little bit of valgus in this case to really try to get our graft seated, and we've got it down, but not you wouldn't hold that for me again Henry, and so we may have to still use a persuader here. All right, so we do our best to try to get it down with manual pressure, I knew that was gonna happen. You may have to re-clamp it. Yeah, let's go ahead and make sure our femur's clamped there, but I think even if we don't get it completely seated with a flexion extension cycle, what that does is the corresponding articular surface can then provide the concavity for our convexity and kind of deliver the graft into a depth all kind of with one motion, and then finally if we need to, once we've done everything we can with manual pressure, we can use a little bit of a concave tamp to just tamp that graft in place, and we can kind of check, make sure that we like our margins, and again we want to impact it minimally as much as we can, and so we've got a nice line to line fit anteriorly, a nice line to line fit at the notch, nice posteriorly, just a little bit here, and so we're just gonna lightly make sure it's down. Okay, now if we like our fit, which we do, we feel like it's good all over, then we can just cut our strings. Can you hold that for me? Should I take it out with the strings just to show people? So at this point, if we didn't like our fit, you take all four of these strings and you put tension on them, but at the same time you either put a freer or a finger here so that the graft doesn't fly out, and you can slowly pull your graft, and these strings will allow you to deliver your graft, and you can then graft below it if you need to put a shim in, or you can retrim your graft, and so if we like it, then what we'll do is we'll just cut the suture at these margins, and oftentimes we can get the entirety to pull out, and so that allows us to get our graft in, we get all of our margins set where we want it, we're nice and happy, and then we can come in and look at our fit and our radius of curvature and make sure that we're really happy. We do that maybe before we pull the strings, but we're looking for a line-to-line fit. Remember, a half millimeter in either direction, either elevation or depression, half millimeter in elevation, then we get contact pressure elevated a half millimeter in depression, then the body thinks that there's nothing there at all, so we got a pretty good fit. We may have a little bit of a ridge posteriorly, but you know, we could hit this again a little bit, but I think we've got a pretty nice fit everywhere. You can see that the contour and the radius of curvature in both directions is pretty nice, and then irrigation, close, we make them touch weight-bearing, we can let them weight-bear relatively soon, but oftentimes we'll wait six weeks, and then we think that incorporation generally takes more than six months, but the literature has said that we can let them get active even sooner than six months. We've got a lot to learn on our rehab and on full incorporation principles, but overall, again, a nice option for our focal defects. So again, a dowel graft in multiple diameters, an oval graft if we need to, and that jig set's a little bit more complex, but I think a useful thing to use as well, and then there are zone-specific graft sets for the trochlea and patella, but again, in our population, sometimes a little bit harder to use because we're facing some dysplasia in those areas. All right. Sorry that took a little bit long. No, I loved it. Great technique, great pearls, really appreciate it. Most everything you said is also applicable to the patella. Absolutely, yeah. All the core concepts are the same. So if we're going to graft this lesion, same principles, everything we would do the same, it's just our anatomy and our graft fit is a little bit more complex. Got it. Thanks so much, appreciate it. Love it. Thanks, guys.

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