So our first is talking about NPFL only. Can we invite Seth up to the microphone? He will be talking about NPFL reconstruction, when, how, and what are the outcomes and predictability when we do it in isolation. Thank you. Thank you. I'm honored to be here. A little bit of perspective for this talk. I work at a university, so I take care of the USC athletes, but I also take care of the general student body of USC. And so I see straightforward patellofemoral instability, and we see a lot of it. And so for most of the cases that I see, isolated NPFL reconstruction is enough. So here's an overview of the talk. We'll focus on the surgical aspects, like when and how, risk for failure, and what graft should you use. The NPFL, as we know, goes from the supramedial patella to Schottel's point on the femur and provides 53% of the restraining force to prevent lateral instability. Diagnosis is key. It's really critical when someone comes in with an anterior knee problem to differentiate instability from pain. So with HMP, radiographs, three-dimensional imaging, we're going to establish a diagnosis. So typically, when we see a patellofemoral instability event, I start with x-rays and MRI. And I will add CT scan only if I'm planning a tibial tubercle transfer. And what I look for in MRI is I look for the severity and location of the NPFL injury and whether or not there's any damage to the articular cartilage. So when is acute first-time patellofemoral instability surgery needed? Well, for the most part, if you have an osteochondral fracture or a major chondral injury or a complete disruption of the NPFL, those are the patients that we go after early. And those patients with a complete rupture on the NPFL, obviously, you'll see it on MRI. But what we see is a static subluxation on the sunrise view. So I treat most of my patellar dislocations non-operatively. But I'm getting a little bit more aggressive to try and prevent cartilage injury. It's kind of like shoulder instability. The more times you let it dislocate, the more cartilage damage you're going to receive. So if a patient's having second or third instability events, I will offer them surgery. So what about that patient with the loose body, large, loose body in the lateral gutter? You can see loose body there. In this setting, obviously, this patient needs acute surgery. And we'll fix that with two bio screws and then do an NPFL reconstruction on the way out. So who is a candidate for NPFL reconstruction? Obviously, failed conservative treatment with a quote, unquote, reasonable trochlear dysplasia and TTTG distance. So where is the cutoff where trochleoplasty and tubercle osteotomy should be considered? Well, I'm glad that's why we have three talks, because this talk's not going to cover that. So who is likely to re-dislocate? Well, in all these studies that look at the natural history of patellar dislocation, it's the skeletally immature and those with trochlear dysplasia. Dr. Dom from the Mayo Clinic had a 31% success rate for non-operative treatment and 3.3 times rate of surgery for the skeletally immature patients with dysplasia. So will an isolated NPFL reconstruction work? In a lot of cases, yes. This is Dr. Schubenstein's work from HSS. She published a series of 90 patients with isolated NPFL, kind of ignoring TTTG distance. And the average was about 14.7, and she had great results. And there have been two really good recent meta-analyses which show a really high number of patients, low re-dislocation rate, low re-operation rate, but a trend towards worse scores in the TTTG distance more than 20. Another meta-analysis over 1,700 patients showed low re-dislocation rate and apprehension, ALTA, dysplasia, and obviously high TTTG distance were a problem. So what about allograft versus autograft? Well, this is one case in orthopedics where allograft might be equivalent or perhaps even a little bit better because you decrease OR time, decrease donor morbidity site, and lower your failure rate. So what about single versus double bundle? There's a slight trend in meta-analyses towards double bundle being slightly better, but you can over-constrain the knee if you get your double bundle too tight. So my technique is two incisions. I connect them extra-articulately. I fix it on the patella first and then dial in the tension at Chottel's point, and I fix it in 20 to 30 degrees of flexion. I make this a check rein. It's not ultra-tight like an ACL. So where do we put the MPFL femoral tunnel? It's going to be one millimeter anterior to a tangent line off the posterior cortex and 2.5 millimeters distal to the medial femoral condyle. If you create an anterior femoral tunnel in a non-anatomic tunnel, you're going to overload the medial cartilage. If you make it too proximally, I think this is the worst complication you can have because then you make it tight inflection, end up with the manipulation. I would air distally so that you're tighter in extension. So MPFL reconstruction, my technique, a little bit higher than the 50-yard line on the patella, find Chottel's point on the femur, and we dial in that graft, fix that 20 to 30 degrees of tension. So in summary, we operate early on osteochondral fractures and loose bodies. If there's failure of conservative treatment in the younger athletes with dysplasia, we do an isolated MPFL reconstruction. Very important not to over-constrain the patella. The femoral origin of the MPFL is most important. You're going to have greater than 95% success rate if the TT-TG distance is 15 or less, and even with some dysplasia, but how far can you push? Allograft is okay to use, double bundle perhaps slightly better, and we consider tubercle transfers and trochleoplasties with severe bony defects. Thank you.

NPFL reconstruction

patellofemoral instability

surgical aspects

diagnosis

osteochondral fractures