Dear ladies and gentlemen, thank you very much for the opportunity to present a small overview about how I understand MPFL reconstruction over here in Munich, and thanks, Andy for having the chance to be here. So, first a little bit on the anatomy. We by now know that the MPFL or in general the passive medial patellofemoral complex has the highest restraint against the lateralizing force of the quads and this is a very nice preparation from Japan, the more reflects the more the patella glides into the trochlea and as you can see by this orange line is working like an edge like hold it statically in the center. So overall, we agree that the bony and static pathomorphology is itself influencing signs of unstable patella, like an increased shift and increased tilt and even a higher rising patella but it's also influencing from birth on the integrity of the medial patellofemoral complex and making it insufficient and weak, and so the way of a rupture is very easy. In early years and ages, the first idea was to duplicate the vastus medialis and it worked in some cases when the MPFL has ruptured and the patella insertion and we resutured it directly at the point of rupture. Then we started in the early 2000s to reconstruct something with a giant needle technique, Yamamoto technique atroscopically, and we found out in a retrospective study that we had a quite higher dislocation rate, mainly when this plastic trochlea was present. This was more or less like the key point lecture or scientific study to show us that the MPFL is the most important structure to keep the patella in place on the passive stabilizer side or to be reconstructed in cases of instability. Once more, we have here another preparation and then first studies popped up, proving that this structure is the main stabilizer and helps a lot to keep the patella stable. So how was this to be reconstructed? We knew that it was something which is inserting in the upper part of the patella and getting to the femur somewhere around the femoral tubercle. Furthermore, we knew it was a double bundle structure and it looked like a sail, so it would be reconstructed. So our first idea is, as you can see here, was a very wide open procedure and we took an autologous graft, and this time it was a semi-tendinosis, drilled it all the way through the patella and fixed it on the vastus medialis. Nowadays we know better because this was harming the vastus medialis, and yes, the kneecap became stable, but the vastus a lot of times got atrophied. Next thing was our first minimal invasive technique, where we inserted with two anchors in the patella and fixed it with an additional screw in the femur. And as you can see here, this was the first drawing I did, and we have been at this time not really in an okay spot, as you will see later, but this was already a first thing where we could reconstruct the sail-shaped double bundle structure as in real anatomy. Diagnostics are pretty simple in my eyes. You need to understand the apprehension test and you need to note when it starts to get positive. Therefore, I recommend to examine the patient going from flexion to extension and not the other way around, because most instabilities occur in extension, so patients feel safer if you start in flexion. Next thing is the J sign. To see from what point onwards, obviously the lateral trochlear facet is missing and the patella is popping out. As a radiological examination, an MRI is demanding. Why? Not only that you can see the integrity of the cartilage, you also see the cartilage groove and that the bony groove of the trochlea. Furthermore, you see the status of the MPFL, you can measure tilt, shift, and you have a reference line you do not have in a sunset view. Then the clinical examination, as you can see, is having the J sign and seeing what happens. You can see here close to extension, it pops out. Then we do have significant instabilities like this one, where the patella is lateralized ongoingly. Those are like reasons for failures if you use it for an isolated MPFL reconstruction, because it's more than only a ruptured MPFL. This is our guidance we use here in our institute. We have a green, yellow, and red sign for sure. In any case, we need to undergo an MRI and, if indicated, additional torsional alignment radiographs like a CT scan or, if possible, MRI also. The easiest group is the one with an instability only between 0 and 30 degrees, and this is the best indication for an MPFL. Every patient who has an instability of his kneecap, inflection degrees more than 30 degrees, you should consider additional focus on the bony malalignment such as trochlea dysplasia, torsional malalignment, because here I'm not sure that an MPFL only will be the solution but has to be done in combination with other surgery procedures. So we focus here on an isolated MPFL taking place in between 0 and 30 degrees inflection. That's how we do our reconstruction nowadays with a free graft. Normally it's used to gracilis with anchors to insert in the patella in smaller sizes. They're getting smaller and smaller every year due to the improved technology and the right spot at the femur. With this technique, you have a free range of motion directly after surgery and an early rehab is possible. This is the perfect indication for an MPFL reconstruction. Isolated, as you can see, the instability takes place up till 30 degrees inflection. If I flex more, the kneecap is stable and on the left side you see that there is an MPFL rupture from the patella with a slightly flat but still existing trochlear groove. This for sure must fail if you try to fix this with an isolated MPFL. Here I really overestimated my knowledge and as you can see it is an internally rotated dysplastic trochlea and the MPFL didn't lead to anything. Using a MPFL in serious dysplasia rather not. Why? Even if you're medializing the patella and you could fix it, you would increase the patellofemoral pressure by the pull towards posterior and you would, let's say, buy stability for the price of pressure and pain and early cartilage degeneration. And that's what is happening then, that the patella pops out one more. And that's what is happening then, that the patello pops out one more. Another wrong indication for an MPFL is a patellofemoral arthritis. Due to the same reasons you should not use it in a flat trochlea, you have the problem or the risk that if you do it in those cases that you increase the patellofemoral pressure, create pain, and accelerate the degeneration of the cartilage. The construction has to be anatomical and biomechanical correct and has to have two bundles. Why? The one is tight in extension, while the lower one is tight in flexion. The surgical technique, if you use it, the anchor system in the patella should take care that it's really in the bone. I take especially care that the upper hole is drilled a little bit oblique towards distal, otherwise you risk, you can see on the picture on the right side, a proximal blowout. The most crucial part in the reconstruction, whatever graft, whatever technique you use, is the femoral insertion. It has to be at the anatomical correct point. If not, you risk higher pressure, limited range of motion. As you can see in the first drawing of my first technique published in 2004, the insertion was on the left side, far to anterior. This is what we did to study to identify the original point. And as an anecdote, since it was late night, I used those little metal balls from the bathroom to identify the spot when I did the study. If you have two fixations, too far proximal or too anterior, they become tight in flexion, and either you have a limited range of motion, or you get pain, or in worst case, even more. So femoral insertion is the key point. Whatever point you prefer to use, your variation is about two millimeters, depending on the study you're looking for. If you take the meta-analysis of an MPFL reconstruction, the free gracilis graft has been the most examined. We could see nine relevant studies with 320 reconstructions, a redislocation rate of less than 3%, and a complication where S mainly have been fibrosis, while the Kujala score increased significantly. Other techniques absolutely are correct to perform, coming up in the moment, is using a flapped quadriceps tendon. Their first series in technical notes have been published, showing good results. Until now, we have a little bit of a missing evidence, which will come in the near future, I'm sure. Results is that the gracilis double bundle has the longest follow-up in the moment, and there are a lot of alternative methods which have not yet been studied in the same way, since they are young, but they show very promising results. And for the future, we need more techniques to also cover the cases, which are revisions, cases in small patients, after fracture of the patella, etc. We studied our own cases, and in the revision cases we were performing in between 2017 and 2019, we could include 32. We included causes for failure as determined by the guidelines of the German Atroscopic Society, and made a systemic analysis of our patients, focusing on recurrent patellofemoral instability or pain after an unsuccessful first operative stabilization. And what we found is that 45% have been a poor surgical procedure, most of the time the femoral insertion was not hit at the right spot, and 30% of concomitant pathology have not been addressed accordingly. In 4%, the primary radiological diagnostics have not been enough, so it was not extensive enough. In the small group, there also was an implant failure by a trauma, was never the case, as well as growth plate or still open gross visors have caused any problem. So, MPFL reconstruction, in general, is an easy to perform mini open surgical procedure. New techniques are up and coming, and I welcome this very much since we need them, since we will see more and more revision cases. We need to work on new and smaller minimally invasive techniques, since our patients are young, and we have to find something for the time of growing, and respect the indication, and most probably, whatever surgical technique you use, the femoral insertion. I thank you very much for your audience. Yours, Philippe Schottler.

MPFL reconstruction

Medial Patellofemoral Ligament

surgical techniques

autologous grafts

anchor systems