specifically about the patellofemoral joint and the complications we tend to see and how we can avoid them, and as we said, practice and rehearse what to do when they happen rather than just reacting, because I think that's a really good way to think about complications. As Matt said at the very beginning, if you're operating and you're a surgeon, when you're a fellow, you're going to have complications. There's not a question about if you're going to have a complication, it's just a matter of when. And I think that's a really good thing to think about when you're practicing, because you can rehearse what you're going to do, and not just rehearse how the case goes, but rehearse what happens when there's a complication, so you know already beforehand what to do. I have no disclosures relevant to this talk. So very specifically to preoperative planning, Chris actually didn't say this, but I've heard him say it a million times to his fellows and to his residents, and I think it's really good. When you talk about a complication, you want to know was it a preop complication? Was it a failure of what you did preoperatively? Was it a failure of something that happened intraoperatively, or was it a failure of something that happened postoperatively? And I think that's a really good way to think about them and compartmentalize them, because then you can start to think, well, how do I avoid them at each step of the way, and if they happen, what do I do? So preoperative planning is extremely important in the patellofemoral joint, making sure you know what you're treating, and I'll talk about that in a second, because it's more sometimes than just instability, and also knowing the most complications of that surgery and how you can avoid them and what to do if they happen. But just as a quick example, I went into a case probably about a year ago of a patient whose measurements did not seem like, in fact, they were very normal measurements, and even though she was dislocating or subluxing inflection, I should have understood that this was a much bigger problem than something that I was just seeing, and instead I lived and breathed by the measurements, and I went in with the assumption that we were going to do a derotational femoral osteotomy because she had the numbers for that, an MPFL, and maybe a lateral lengthening, but I did not plan a tibial tubercle because of the fact that her numbers did not demand a tibial tubercle. They didn't meet the criteria. I should have been aware that this was a much bigger problem than anything that we were seeing, and when we got in the OR and we did everything, I still couldn't keep her located without the tibial tubercle, and so I wasn't prepared for that. I've done them a lot, so I went and I said, okay, well, what do we have to do? I'm going to ignore what I saw in the MRI. I'm going to treat what's going on here. She's still dislocating, and I can see the tubercle is lateralized, so sometimes you have to be able to, at the time, say, how do I get this patella to be stable, and not just rely on the MR imaging or the x-rays, but rely on what you're actually seeing at the time and in the moment, and obviously, as Chris said, you've got to get good at playing badly. That's a Jack Nicklaus quote, so you've got to make sure that patient comes off the table with a stable patella, and we did. This is one of my favorite quotes. Good judgment comes from experience, and unfortunately, experience comes from bad judgment, so when I'm teaching my fellows about complications, I'm usually telling them that the reason I can tell them to avoid something is because I've made that mistake myself many times, and so what I want to try to do is teach you how to avoid the mistakes I've made. You'll make your own. Everybody does, but at least you can avoid some of the ones that I've made in my time. How do we know what we're treating? Well, this is really the preoperative part of this. Patients come in. Their kneecap is dislocating, and you want to say, well, is it just instability? Well, if it's just instability, well, we can do this, this, or this, but what you may not be hearing from them is the fact that they have underlying pain, and so there's this crossover in the group. Some patients have pure malalignment, and they have pure osteoarthritis and lateral malalignment and no instability. Other patients have pure instability. They don't have pain. They just have pain when they dislocate, and then they get right back on the soccer field three months later or two months later, and they don't have pain in between episodes. Other patients have both, and this is really the group you don't want to miss because you can treat them like an instability patient, but then we end up with a stable, painful knee, and that's really not the goal, and that to me is a failure of the preoperative workup and listening to the patient and understanding or seeing subtle things like the lateral, maybe some mild lateral wear on the patella before their cartilage really starts to break down. So this is a big question that's always asked. There's always a talk on it. Isn't MPFL enough? Can we just treat these patients with an MPFL, and sometimes it is. Sometimes you can look at the anatomy, and it's pretty straightforward. They dislocate. They have a pretty well-contained patella on the other side. Their anatomy, they always have a little bit of ALTA or a little bit of trochlea dysplasia, but it's not terrible, and then other times it's really obvious that it's not enough, right? You have a patient who stands in front of you, and you just know that that's not going to be an MPFL, and so those are, luckily, that's the extremes, but there's this big group in the middle, and this MPFL obviously was not going to work because it was never going to be able to compensate for that kind of bony failure, and you can look at this patient and say that is just not going to work, right? An MPFL in this case is not going to work. But for the vast majority, there's this big question mark. Do we do just an MPFL? Do we do more? In the office, obviously, there's things that should alert us to the fact that this is a big problem, not a little problem, and so when you see certain things in the office, as Matt kind of made the judgment before, you want to make the decision like, okay, I got to really rethink this. Let's really rethink our game plan here. So there's still some gaps in the literature, which obviously make it harder for us to make these decisions, right? Who needs an isolated MPFL versus who needs an additional bony surgery or realignment? And as I said, some are obvious, and most are not. We need better high-quality studies and more large multi-center studies, but currently we use our best judgment. Who needs a distalization? Who needs an MPFL? Who needs a derotational femoral osteotomy? But there are certain tricks to what we do technically, and I do want to get into the weeds a little bit on the technical part of this. So for the MPFL, I always say if we can know what the complications are and know what the biggest problem is, then when we get to that part of the case, we can struggle to make sure we don't make that error. So obviously in the MPFL, we want to look at the technical points. Through the first, we want to know what the normal MPFL does. Through the first 50 to 60 or 70 degrees, the MPFL should stay fairly isometric, and then as it engages in the distal port of the trochlea and you get into the blumen sets and the notch, you're going to start to see that ligament loosen, or you should. The femur is the key to this isometry, so we focus a lot on the patella for other reasons, but not for the isometry. A little bit, but most of it, 90% of the isometry is deemed by the femur. So how do you get the right spot on the femur? A lot of questions on this. I don't really care whether you use anatomy first, which I do. I find the landmarks. That helps me position it, and then I just confirm it after I know it's working well. So you can flip one and three here. You can put the image before the anatomy, but whatever you do, do not stop and forget to check isometry. You need to know that that ligament is working like a normal MPFL should work. I take a picture at the end of every case with that knee in full flexion, because if that patient struggles to get their motion back, I want to know it wasn't me. I want to know at the end of that case, I was able to bend them completely up so that I don't worry about them having motion, and if they're getting tight, I know it's because the rehab or something that happened post-op, but not an error that I made in terms of the positioning of my tunnel, and you can see that because I see it all the time. I show fellows. As I put the pin in, I check the isometry, but the image can get you to about where you want to be, but it's not going to get you to the exact spot every time because there's no spot. Even Philip Schottel, who actually published the paper that was done on eight cadaveric knees that all had normal anatomy, not trochlear dysplasia, not patella alta, not TTTGs that were elevated. It's an area, and you want to be in the vicinity, but you want to make it to the patient. You want to be patient-specific, so finding the anatomy is helpful for me because then I'm putting it based on the patient's anatomy, and then checking that isometry is really important. We'll go back to that in a minute, but I want to focus on the complications we see. In the patella, the most common complication we see is a fracture, and this has gotten better actually over the last five to ten years as we see like the mid- and the long-term outcomes. We're much better at dealing with the patella, but the fracture is still the number one thing we worry about, certainly the most important. How do we avoid it? Well, I used to use a docking technique. I used to use a technique where I'd put a pin in. I'd ream a short, blind tunnel, usually with a five-millimeter reamer, and I really didn't think much of it. It didn't require any anchors or any fixation other than shooting two sutures across and tying it over a bone bridge, so I thought this was a great way of making sure that I got the patient to where they needed to be, and I didn't have to worry about anything except I started to worry about my tunnels after doing this for about ten years. I luckily did not have fractures, but I did worry, and I obviously still could, but I did worry about them. So I started to use anchors. Obviously our anchors got better, and I started to use anchors for my fixation. I liked it for two reasons. Number one is I didn't need a tunnel, and I didn't have to worry about fracture as much, or I thought, but in addition, I also liked the broader fixation, which more recreated the anatomic NPFL, a larger, broader attachment to the patella rather than spot welding, so to speak. So I used two anchors. I don't care what anchors you use, but I used the two anchors, and I thought, okay, well, you can't do anything, and this is a friend of mine who gave me their complication so I could show it, and these are two simple suture anchors, but if you look at the bottom one, you can see that that anchor wasn't placed in the right spot. It's a little too anterior, and so even with a small anchor, you can get a fracture of a patella, and that's really, I mean, we all think, oh, I use anchors, I'm protected. It's not. So the error that I coach everybody in that I've made, I haven't had, luckily, I knock on wood, I haven't had a fracture of the patella, but if you do, we all can fix a patella fracture, but it does jeopardize, obviously, the NPFL, and we've got to figure out how that happens. So if there's ways we can avoid it, and the biggest issue is that everybody wants to avoid the cartilage, so everybody errs on going to anterior because they're worried about the cartilage, and I tell my fellows, don't worry about the cartilage. Get right on there because it's just like a bank card. It's the odd facet. Get right onto that cartilage. You should see the cartilage. That's what I like to do. I like to make sure that I get to where I think I'm going to be. I kind of create my landing strip, but then I make an arthrotomy, always, and the arthrotomy is for two purposes. One, I can palpate the patella so I know the length of the patella and where I want my NPFL to be attached, but number two is I'm looking at the cartilage when I'm putting my anchor in, and I am literally right on the face of it, just like you are with a bank card, and that protects you from being too anterior, but people want to avoid the cartilage because they're worried about injury to it. If you're right on the cusp, it's really a great way to ensure that you're not too anterior. So what's the femur complications? We know these. We've heard about them. We see these horrible. I have a library of these pictures, some of which are my own. The malposition tunnel, obviously it doesn't give you enough room to make it around the corner. You can avoid this because if you've checked isometry, you may end up in a radiographic not as ideal position, but at least you know that for that patient, that ligament is not getting tighter inflection, and that's really the major issue you want to be able to avoid. So we want to always look at where that tunnel is. If you're too high, and David Dedick has a great way of expressing it, high and tight, low and loose. If you're too proximal, you're going to end up with a ligament that's tightening inflection. That's really the thing you want to avoid. Obviously that can't make it around the corner. That just doesn't have enough length. That patient is going to get stiff. They're going to have pain. They're going to come into your office, struggle with their motion, and if they do get their motion back, which they might, they're going to stretch out the graft and have recurrent instability. So that's what we want to try to avoid. And how do we do that? Again, for me, I use anatomy. You can use image, but whatever you do, check the isometry when you're in there because that's going to give you the real importance. This is one that's too low. Sometimes it's too low because the physis are there. So you do the best job you can. But if you're dealing with a skeletally immature patient, and I've done this before, you are restricted by the physis. So the younger they are, you may have to err on being a little too low. And in those cases, you struggle to do other things. We talked about this yesterday. Sometimes we do a patellar tendon imprecation if they have a little bit of alta if they're skeletally immature. And you are bound by some of this because of that, and you can explain that to the parents. I have very frank conversations with the parents when I deal with this that they may have a re-dislocation, that we are restricted by their physis. I try to alert the parents and the family to what the issues are so that when they do happen and they do, we can talk about why they happened and how to address it at that point. And we even talk before the surgery about what we'll do if they fail. If they re-dislocate, what's the next step? So everybody is on the same page. So when a complication comes into my office, whether it's my own or anybody else's, I think the biggest issue in patellar instability is understanding what is it that is the complication. And that's different for everybody. Sometimes they're perfectly stable, but they have pain. Sometimes they're unstable, and they don't have pain. And the worst combination is when they're unstable and they have pain, and that's really what you want to try to avoid, and that's what we want to try to see coming. So we want to figure out what went wrong the first time. Was it tunnel placement? Did it occur before the surgery? Did I or the other surgeon miss the fact that this patient was an overloader and that pain was a large part of their complaint? And did I just do an MPFL, which gave them stability but didn't treat their pain? That's a pre-op problem. Was it an intra-op problem? Did I put my tunnel in the wrong place and now they're failing to get their motion back? Was I too high? Are they struggling and they have pain because they're too tight? Are they too loose, and are they having recurrent instability? I want to know all of those things when they come in so I can figure out how to address it and change what happened the first time and make sure it goes right this time. So again, avoiding tunnels on the patella, using the landmarks on the femur, and again, for me, most importantly, checking the isometry. This is just a video of the isometry because this, to me, is the most important part. Again, I use pin placement based on anatomy first, and then I check my isometry, and at the end I just confirm that I'm in the ballpark because that's what's important. Looking at these two lines as you go through a full range of motion, they should stay congruent all the way through deflection, and then as long as it's getting a little bit shorter and changing in deflection, I know that's an anatomic or a normal MPFL, the way the MPFL should behave. And then I get image to confirm that, which I think is really helpful. Sometimes I don't even get to the image. I stop at isometry. I know it doesn't work. I change my pin placement based on the fact it's getting tighter in flexion. I'll take my pin out. I'll try again, and then I'll check the isometry again, and then I use image at the end because I think if you're not checking isometry, you're not going to ever really know what you have before you get off the table, and I want to feel confident that I can bend that knee up all the way and that the patient can do the same. And then I think trying not to over-tension, and I make this mistake almost probably 20 percent of the time. I dock my ligament, and I use a blind tunnel, so I dock it, and then I check it. I make the fellow feel it. I ask the fellow what they feel. They are like, it feels a little tight. I want everybody to know what that feels like when you've made a patella too tight. It's not an ACL, so I always try to feel that. I still do it. I still err and make it too tight. I take the screw out. I do it again. You have many chances, but before we get off the table, we stop, and to the point that I think Allison made, Chris and Matt all made, and Atul Gawande has said it as well. You want to do the things that are not relevant quickly so that you can do the things that are most critical slowly. So you'll see in your cases, I'm sure you all do this too, you're kind of speeding through the stuff that has no, you know, the approach, the diagnostic arthroscopy, all that stuff, so that when you get to the moment where you're docking your ligament, and when you're finding your tunnel placement, you can take the time you need to get it right, and that's a big deal. And if it's not right, I take it out, and I do it again. And actually, I tell my fellows, you get three tries with one screw, and you know why I know that? Because I've done it many times. I actually had to change the screw because it's taken me more than three times sometimes. So it's not a problem as long as you address it before you get off the table, and you know when you got that patient off the table that that ligament is not over-constraining that knee. TTOs, TTOs are a big part of any patellofemoral practice. It's a really useful tool, not just for patellar instability, but also for patellar malalignment and offloading. And this is a big, it's an incredibly versatile operation because you can do two things with one operation, three things if you include distal eyes, which is really impressive. You can distal, you can anteriorize a lot, like on your left, which is a big bump, and I tell patients they're going to have a bump because sometimes they're unhappy with that. So I tell them ahead of time, especially if they have pain, I tell them you're going to trade that for a bump. Or you can anteriorize them a little bit, like you can see on the right. So it's an operation that you can cater and taper. And whatever you do, obviously you're going to put the NPFL where the NPFL goes, but the TTT can be very variable. Depends on the patient's own anatomy. So distalization is one thing I want to talk about, because that probably has more complications than actually Andy Cascaria's in the audience, and he wrote a paper with me, and he showed that the distalizations do have a harder time healing, which makes sense. We've lost a point of fixation. He uses three screws for his osteotomies, which did tend to heal better on x-ray than mine. I use two. I like the compression I get with two. I've done some things since the study to change it, but I still use two screws. But again, the things that I tell patients before all of these, chance of nonunion, chance of fracture, and I think that's really important for them to know that if it's a distalization, their chance of fracture is higher. It's a complication that we know that happens. So I tell patients about it in the pre-op session so that they know it's a risk. And then I have patients where I've had my own fractures. This one on the right is mine from a long time ago, and that's the same patient that's on the far left of that screen. That's my fracture. I actually landed to give a conference, and my NP sent me this picture. As I was landing, I got this picture. So I actually was luckily with John Fulkerson. I showed it to him. It was a little bit earlier on in my practice, and I was really heartbroken. But it happens, and I think managing it, and you'll see that having the ability, and by the way, the same way to treat this, to treat a tibial tubercle shingle. If you're in the OR and you can't get fixation, and so we've had that problem, you want to have a plate and screws so that you can make sure you can get fixation of that tubercle. If you fracture the tubercle, you want to make sure you have the stuff in the OR to treat that at the time, and you want to let patients know, and I told this patient's mom, this is really related to our surgery. We imaged the other side. We made sure to get a CT of the other knee, which I had done, which did not have any nonunion or delayed union at the bottom, and then before she went back to playing, we actually imaged her as well once I had revised it. Baha is another thing. So overcorrecting in the OR is a big deal. You want to make sure you go into the OR with the exact measurements that you want to distillize based on the MRI. Make sure you know what the contralateral knee looks like. Most of the time it's symmetric, but I try to set them at the high side of normal so that if I do overcorrect, I'm not going to end up with this problem, which is Baha, because this is a problem where the patient will come in and you'll have more pain. So again, what do we do ahead of surgery to prevent complications? We try to have the best preoperative plan. We want to make sure we know everything that's coming. As I said, I got stuck in the OR not having made the correct preoperative diagnosis, and I had to correct that intraoperatively, and that's not a great feeling, but at the end, you got to make sure you get off the table with the patient with a stable knee. And also, you want to know the most common complications and how to avoid them. So thank you.

complications

patellofemoral joint

preoperative planning

intraoperative failure

postoperative failure