Thank you, Ed. Pleasure to be here. No disclosures. So here's the challenge. So many people in this room take care of athletes, and we're trying to get these athletes back after a patella instability episode, which is a relatively common event that we see, and make decisions about when to operate, especially the decision-making part of this. So anybody treating patella instability needs to really understand the MPFL, the medial patella femoral ligament. It is the tissue immediately distal to the border of the VMO. It provides 60% of the restraining force to prevent dislocation, and think of it as guiding the patella into the trochlear groove, and the first 30 or 40 degrees of flexion. Upon that inflection, the bony anatomy kicks in and really provides the restraint as the patella gets deeper into the trochlear inflection. When the patella dislocates, practically speaking, the MPFL is disrupted and incompetent. Anatomic studies and MRI studies show it tears at least 87% of the time. If the patella dislocates, there's no way that MPFL is competent and functional. So just assume it is torn 100% of the time for practical purposes. Now the challenge is, who gets surgery? Because there's a wide range of studies that show variability in terms of recurrent instability. Roughly 40% of recurrent instability. So we operate on everybody with a first-time dislocation, we're operating on too many people. But the challenge is, each recurrent instability event can come with a price. It can be permanent, catastrophic sometimes, articular cartilage injuries. I think all of us that do surgery on these have seen this. So decision-making is key here. Non-operative treatment has a very successful role for some of these patients. It's going to focus on quad strengthening, especially the VMO. The hip is very important, especially the abductors and external rotators. You're trying to avoid this vulnerable, dynamic valgus position of the knee with athletic moves. And you can also supplement this with a patella tracking brace, which is really an adjunct until your muscles are strong enough, not a long-term solution. Now immobilization, if you keep them out straight, crutches, whatever, initially has no impact on the success of non-op treatment. It does not influence recurrent instability. So keeping them in a brace for a period of time is actually causing that patient to lose ground and lose quad strength. So it encourages people to basically only immobilize them if necessary for pain short-term till the swelling improves, but work immediately on strength. The stronger they are, the more successful non-operative treatment, plain and simple. Recovery is going to be indicated for those patients with recurrent instability. Again, preserve that articular cartilage. Some of these patients just can't progress with rehab, and the patella after that first episode is tracking very poorly. They have a lot of pain. It's subluxing all the time. If it's bilateral, the writing's probably on the wall. And also if you have articular cartilage damage on that first episode. So everybody in my practice with a patella dislocation event comes in the office, gets an MRI. I'm going to assess their anatomic risk factors, look at their articular cartilage, and advise them on the pros and cons of surgery. Now it started with the premise that the MPFL is disrupted and incompetent, so why not just repair it? Why not just imbricate it? Well, the problem is you don't know where it's torn, and I challenge anybody to reliably find that location on an MRI or even surgically. It's not so easy. So if you just imbricate this and it's torn off the femur, well, it's going to stretch out. And we know this very well. So this is not advised. So a repair or a VMO advancement or an imbrication, all those are destined to have a high failure rate. A couple of very good studies that show basically equivalent outcomes with non-operative treatment. So that is not advised. Instead, use a graft. Restore the anatomy. This is safe, reproducible, and predictable. And the gracilis is actually stronger than the native MPFL. So the gracilis is my go-to graft. You can use a SEMI-T, but it's more than you actually need. Gracilis is stronger than your native MPFL. And the key is where you put it. And the crux of this operation, the outcome, is the femoral location of this graft. And if it's misplaced, then the graft's behavior is going to not be what you need for success. And there's different locations on the femur that you see on that bar graph at the bottom. And the green line that's going up is the graft getting tighter in flexion. And that's if the graft is placed too proximal. That's the worst mistake you can make. We coined the term high and tight because the graft's getting tighter as you flex. Either they're going to not get their flexion, or they're going to rupture their graft. So, and outcomes have been shown to be very good. The return to sport is excellent. The redox location rates are low. And the rehab is pretty quick. I mean, basically four weeks on crutches, soft tissue healing, range of motion is tolerated. If you pick the graft location correctly, they're going to do very well. And a symptom-based return to sport as early as three months, probably more likely around the four to five month range based on strength return. But we need to identify the other risk factors that go, that contributed to patella instability and whether or not they need their anatomy adjusted. Because normal knees just don't dislocate the patella. Patients always have an underlying anatomic risk factor to a varying degree, or maybe more than one. And that's where everybody that's in this room plays a role in advising a patient and determining that risk and whether something else needs to be done. Whether you're the athletic trainer, the physical therapist, the surgeon, or the primary care provider. And every patient, I think, ought to have evaluated their anatomic risk factors. And these are the big ones, patella alta, malalignment, valgus, and dysplasia. And understand that if you're trying to pull that patella over with a graft to get it in place, that's probably destined to fail. You really want to get the bone underneath the patella, and then the graft, again, is just guiding your patella into that trochlear groove. And here's a very good study. I think this is probably one of the most important slides of the presentation that looks at a meta-analysis of 17 different studies. And if you start to put anatomic risk factors together and advise a patient on recurrent instability. And the bottom there is probably most important, not necessarily the individual anatomic risk factors. But if you have one, two, or three risk factors, you've got upwards of an 80% chance of recurrent instability. So that may be the person that you advise, perhaps, to have early surgery, rather than wait for that second catastrophic event. So let's break down these anatomic risk factors. So first, malalignment in the coronal plane. The TTTG has replaced the Q angle. This is much more exact. You can measure on MRI or CT. MRI tends to underestimate it. When you're measuring this offset of the tibial tubercle relative to the center of the trochlear groove, understand that you want to pick the middle of the tendon attachment, which is not going to be the high point on the tubercle. If you pick the high point on the tubercle, you're going to underestimate it. This is all about vectors. So you want to pick the center of that tendon attachment on the tubercle. And over 20 is considered abnormal. This is another measure I find very useful, the PT-LTR, patella tendon lateral trochlear ridge. And you're measuring on the first cut that's all tendon, just below the patella, how much tendon is draped over the lateral femoral condyle. So draw a perpendicular line to the apex of the lateral femoral condyle, and then measure how much tendon is draped over the side. And 5.5 was the threshold that's actually, in this study, found to be both more sensitive and specific for recurrent instability than a high TTTG. And it just makes sense. It's a visual representation of the vector that's pulling that patella over the side. So I'm getting both of these measures on every patient. And if these numbers are elevated and I see physical exam evidence of lateral tracking, especially tilt, then I'm considering a tibial tubercle osteotomy or an AMZ to correct that, which is very, very effective. Malalignment or genuvalgum is another thing to assess. If the patient looks like they're in valgus, they'll get long-standing films. And then if the weight-bearing axis goes more than 50% into the lateral compartment, or if they have more than six degrees of excessive mechanical axis in that limb, I'm gonna consider a distal femoral opening wedge osteotomy. As long as the deformity's in the femur, it almost always is. Surgical tip, if you use a femoral head allograft or wedges and put those in the osteotomy site as a placeholder, it holds it very well as you put the plate on. And as you're swinging the leg over into neutral alignment, you're bringing the tubercle with it, so you're actually gonna improve the TTTG by seven to ten millimeters. If the patient is still growing and more than 12 months of growth is left, then you can do guided growth with a Fisial tether with these two whole plates. It can be put across the femur and or the tibia, and it can be very effective. And then once the desired alignment is obtained, they can be removed. Rotation is probably a little bit more of a black box as we're learning more. But how much is too much is a bit of a debate. But if somebody has 35 or really 40 degrees of femoral antiversion, that's probably too much. How can you maybe pick this up on exam? Get them prone. Look at the amount of internal and external rotation they have. If they have more internal than external rotation, then perhaps it's too much. Or if they can get all the way down to 90 degrees, the leg flops all the way out and touches the table, that's too much. And then that person needs a CT scan to quantify it. Patella alta is a big one. And patella alta, we increasingly understand, really has interplay with all the other anatomic risk factors. If a person has alta plus other things, it's gonna make those other risk factors much more pronounced in their effect on that person. So the problem is the knee has to flex much further before that patella has bony engagement in the groove. Two ways to measure this, the CD ratio or CD index looks at the patella articular cartilage length and that distance relative to the top of the tibial plateau. More than 1.2 for a ratio is abnormal. But you can have a high-riding patella or you can have a short trochlea. And they're both gonna have the same impact in terms of the patella seeking that groove. It takes deep reflection to achieve that. So the patella trochlear index, which you see on the right, looks at the amount of cartilage overlap of the patella and the trochlea with extension. And less than 25% is considered abnormal or the effect of a patella alta. This has really replaced the insoluble body ratio because it excludes the patella nose, it just looks at the articular cartilage length. So when you see a patient and on the exam they have a J sign, now that tells you that the patella is completely disengaged from any bony restraint and full extension. When it jumps like this, we call this a jumping J sign, and that's usually excessive patella alta plus a dysplastic trochlea. And that combination is especially problematic. So I'm gonna consider correcting patella alta if the CD ratio is greater than 1.4 or the patella trochlea index less than 20% and a J sign on exam is very important. Now if I have somebody with a very dysplastic trochlea, which you see here, there's a bump, we're gonna get into this a little bit more in a second here. Plus excessive patella alta, there may be an opportunity to move the patella distal beyond that dysplastic portion of the trochlea, closer to more normal patella, excuse me, more normal trochlear morphology and avoid doing anything about the dysplasia. If they don't have excessive alta, then you don't really have that opportunity. But in this person, I moved this person down distally over a centimeter. I shoot for a CD ratio of 1.1 when I'm done, and they were engaging in more normal groove. So trochlear dysplasia is an area that we're starting to learn a lot more about. The key is to understand it and identify it, and that comes from the lateral x-ray. So if you follow Blumensat's line from the notch, as it exits anteriorly, that's the base of the trochlear groove, which is your blue dashed line. And that should be the lowest point of the trochlea, and as you follow it up approximately, that should be flush with the anterior cortex of the femur, in a normal knee, as you carry it on up. If that extends up and actually crosses the red dashed line, which is your lateral trochlea, then they're at the same height, so they're flat. And that's called a crossing sign. If it continues further anterior, which are those green dots, that's what's considered a supratrochlear spur. It's in front of the femoral cortex, a line that you drew straight down the front. When I see this, I know I've gotta get three-dimensional imaging, and that's, you can see sometimes, very bizarre anatomy. And you really can't appreciate that on a sunrise view, and you're gonna see these convex trochlea sometimes, and very, very strange shapes. You see that bottom right CT scan, and you know there's no way you're gonna fix that problem with an isolated MPFL. And our goal then is to drop that spur down flat on the anterior cortex of the femur. And this is a view arthroscopically from the superior lateral portal looking down the knee, this is a 19-year-old female, and look at all that chondrosis she already has, she was a lacrosse player, huge supratrochlear spur. All that, I think you can appreciate, sits anterior to the shaft of the femur. None of that should be there, it should be flush with the front of the femur. And it's like an egg on a table, that convex surface is really problematic in terms of the patella tracking. So I'm gonna try to quantify this, I'm gonna go to the sagittal cut at the notch, which again should be flush with the femoral shaft, and measure how much bone plus cartilage sits in front of that. More than seven millimeters gets my attention. And again, it's not about flatness. So the sunrise view, this is the same knee. The same knee on the left, 45 degrees of flexion, merchant view, looks like a pretty normal trochlea, because there it is a normal trochlea. But in extension, as you see on the right with a CT arthrogram, that convex trochlea, the patella's just teetering on the edge. You can see the cartilage damage, and that's a problem. So I don't make decisions based on that merchant view. I make it on the MRI in extension, or the lateral x-ray. And flatness isn't a problem. Flat on flat can be balanced just fine, often with just soft tissue procedures alone. But it's these convex shapes with the jumping J signs that are important. So I'm gonna look for de jure type Bs or Ds with a spur height at least seven or more, a J sign on exam. And if they have patella alta as well, I know that spur's gonna have a much bigger influence. And this is the scenario in which I'm considering this, or revision procedures. Now, what we do for this is basically create a new anatomy. We're gonna take that spur that sits well anterior to the femur and drop it down by creating a trough behind an osseochondral shell. Almost all of these native trochlear grooves are directed way too medial. The patella can't get over there. So we're gonna line it up more with the femoral shaft and drop it down flush like that. And it's gonna sit right down flush on the femur. We'll hold it in place with vicral sutures while that heals. And so before and after with the NPFL as well. So all the bony procedures, the rehab is pretty similar. You're gonna basically allow time for bony healing with crutches, with partial weight bearing for the first six weeks. Early motion's critical, especially with any of the trochlear procedures, cuz you're inside the joint, you can get prolific scarring. So embrace just for fall risk at first for these first six weeks, and work on range of motion and strength. Return to sport typically five to six months. So in summary, in decision making for these patients, they're all gonna get a reconstruction. They're not gonna get an imprecation or advancement. Reconstruction, I hope I persuaded you, is the way to go. Then the anatomic risk factor thresholds to consider would be TTTG greater than 20, PTLTR greater than six, DFO greater than six degrees of valgus. And dysplasia, as I just outlined, with a significant spur, especially evidence on exam. And patella alter greater than 1.4 on the CD ratio, or a trochlear index less than 25%. So lateral release, you notice I didn't mention it all. So it's the last thing you do just to balance things. A lateral release alone is never the answer, never, ever, ever the answer for patella instability. It does not solve the problem. It does not correct the anatomic risk factors. People do not have a tight lateral retinaculum as a primary problem. They may develop it over time if they track laterally, but it's not the primary problem. Thank you.

patella instability

medial patella femoral ligament

surgery risks

non-operative treatment options

anatomic risk factors