Hi, welcome to MPFL Complications. I hope in the next 10 minutes I'm going to teach you how to avoid these complications. I do a lot of patellofemoral surgery, and unfortunately, I do a lot of MPFL revisions. And if I can do anything in the next 10 minutes, I'll at least show you things to avoid. I co-founded the Patellofemoral Center at HSS many years ago, and I'm happy to be teaching you about this subject. I have no significant conflicts with this talk, but I do consult for a smith and nephew and varicella. So let's talk about what can happen. First of all, the patient can re-dislocate, which is upsetting, but probably more minor than the rest of the complications. Usually this is that you chose the wrong patient for an MPFL reconstruction or said otherwise you're doing the wrong operation. Secondly, fracture, large holes in the patella or a non-isometric graft can cause patella fracture. Patellar bone loss, usually this is because the graft is not isometric. Arthritis, lateral overload on the patellofemoral joint, I think this can be avoided. Medial subluxation, usually because it's an over-tightened graft or you put the tunnels in the wrong location. So as far as re-dislocation, I would suggest that you probably should not do an MPFL if the TTTG is above 15 to 20. There are a couple of studies saying that this MPFL works just as well in these patients. However, based on the MPFL revisions I do, I think this is probably not a great idea in most patients. So here you can see this patient with a failed MPFL reconstruction. You can see that lateral femoral condyle bone edema as a result of a recent dislocation. And there's significant trochlear dysplasia and malalignment in this patient. I don't think this was a great candidate for an isolated MPFL. Secondly, if you overdo a lateral release or a lateral lengthening, here is what I do in the office. I put the knee in extension, I center the patella in the groove, and then I check to see if I can evert the patella to neutral. If I can do this in clinic or in the operating room, then I do not do a lateral release or a lateral lengthening. I think it's easy to over-tighten your graft or cause increased instability by doing a lateral release in these patients. Here you can see a patient with significant patella alta. Now I generally would not do an MPFL if the ketone to shop is above 1.2 without an osteotomy. Also to consider in a patient like this with significant alta that if you are going to do an MPFL, the femoral tunnel may need to go right above the growth plate in order to achieve an isometric graft. And I certainly use flora in these cases with an isolated MPFL. Occasionally you have no choice because the patient has significant instability and you can't wait until the growth plate is closed to do a procedure. And I tell those patients that they may need two surgeries or stage surgery. Here you can see a drawing and a flora shot of Schottel's point, but I would look at this last. I would first palpate the desired position for the graft. Then I would check isometry. If the graft is not isometric, it will stretch and you'll get a re-dislocation. Here you can see the femoral tunnel was too proximal. If it's too proximal, the graft is tight. In order for the patient to regain knee range of motion, they have to stretch out their graft and then guess what, they re-dislocate. Here you can see a patient who had two femoral tunnels. So the first graft failed with subsequent re-dislocation because it was too anterior and therefore not isometric. The revision graft is placed more posterior with a good result. Fractures. So fractures often happen because the anchors were too large, but often they were too dorsal. So here you can see a patella fracture. You get a hint that the tunnels were slightly too anterior. Here you can see after reduction, this patient, I did not do this surgery, but I think it's a good example as you can see how dorsal those patellar anchors were placed. This was after a patellar tendon avulsion repair with large anchors placed distally. It caused a stress riser. This can happen after NPFL as well, so please try to use smaller anchors. Ideally you don't want to make big holes in the patella, but even small non-observable anchors can cause significant patellar bone loss if the graft is not isometric. So here this patient ultimately required a whole patellar allograft to resurface the patella due to the bone and cartilage loss. Here you can see axial view on the CT with loss of approximately 30% of her patella from a non-isometric graft. Here significant anterior placement of the femoral tunnel. If she was going to regain her range of motion, she was going to either stretch her graft or cause significant bone loss. She actually did both. Here you can see the tunnel was placed too proximally in the patella with I think too large of an anchor, but this was non-isometric causing significant bone loss. This can cause quad pathology and quad pain. Here you can see a femoral tunnel placed too proximal and too anterior and no fracture but bone loss in the patella. I worry about these cases as far as future fracture. What about arthritis? So this patient did well after their MPFL. They got 10 years of stability. However, I think they should have treated the maltracking at the same time, not just the instability because you can see lateral patellofemoral joint space nearing with osteophyte formation. You can see on the image below that after an osteotomy with improved joint space and improved alignment, but I think this could have been avoided if this patient had been appropriately treated with an osteotomy at the index procedure. Here in the anterior tunnel, the patient got quite stiff but also overloaded the patellofemoral joint with significant cartilage loss. Here the graft was too tight leading to medial overload. You can see the sclerosis in the medial facet and this patient ultimately underwent a lateralizing osteotomy to unload that medial facet with a good result. So how do you salvage misplaced tunnels? Well here with the revision MPFL and an osteotomy, clear maltracking would require an osteotomy. I don't always get hip-to-ankle films on every patient, however if a patient in clinic has significant valgus, then I do get hip-to-ankle films because I think most of these patients would benefit from a distal femoral osteotomy or a closing wedge HTO. Here again is another example of a patient who's not a candidate for an isolated MPFL. There's more malalignment on the left versus the right but I don't think either knee is a candidate for a soft tissue procedure only. I think it's pretty clear why this patient failed. Good placement of the MPFL but significant trochlear dysplasia and malalignment. This is causing overload to the lateral facet and the lateral trochlea and should have had an osteotomy at the first index procedure. So pearls for the patella, I recommend small anchors. If it's a revision case, consider a quad turndown. I use eight to nine millimeter partial thickness quad graft in these cases. If I don't want to make additional holes in the patella, be very, very careful to center the patella and the trochlea when securing the MPFL. Do this in 30 to 40 degrees of flexion, especially if you've done a lateral release or a lateral lengthening. You don't want to over medialize them. I only consider a TTO if the TTTG is high above 15 or certainly above 20 or if the ketometer shop is above 1.4 or if you see a clear maltracking on imaging or clinically in the office. For the femur, first I would palpate and this is really the most important part about this whole talk. Then check isometry and then check fluoro. And I use a big CRM. I get much better images. Thank you so much and I hope you have a great rest of your course. Bye-bye.

MPFL surgery complications

patient redislocation

fractures

patellar bone loss

arthritis