All those talks are great, great talks. So we've got about 20 minutes. So if you guys have any questions, this is obviously a complex topic when there's a lot of routes to go. But please come on up to microphones to ask questions because they're gonna be recorded, but they won't be identified. So don't worry about if somebody's gonna hear your question and you're worried about it. But I'm gonna start off with while we're waiting. I mean, so Andrea, you mentioned not missing tonus angle, which when we did a study early on, looking at patients that I just did isolated capsular placation on to prove that instability was kind of a thing. And we looked at the anterior center edge, I'm sorry, the lateral center edge angle, and we looked at the tonus angle. And depending on how you measured it, was a different percentage of patients that we classified as borderline as plastic, if you will. And you stress both of those, but what about the role of doing a false profile view and looking at the anterior center edge and how do you use the CT to quantify? Because I know some people have talked about, I think we basically don't do a great job of describing dysplasia. I think maybe the volume in CT makes a difference, but how do you use the CT to help you? You know, the gestalt, you say, yeah, that looks dysplastic, but are there measures that you're using on the CT scan that help you? Yeah, I think you get to the crux of the fact that it's very difficult sometimes to identify these patients, and that's why we'll often see them in the revision setting is that it was missed initially or, you know, worsened iatrogenically. So the anterior center edge angle and the false profile, I do get that as part of my standard x-ray series. So I'll get a standing AP pelvis, a 45 degree done lateral, and then a false profile in every patient for hip evaluation. I think the one thing with the false profile is that it's not as standardized as some of the other images we get. So with a standing AP pelvis, we know that you want your coccyx within two centimeters of the pubic symphysis. You want it centered. You want your obturator foramen to look symmetric so that it's not rotated. But when it comes to the false profile, you know, you tilt the patient a certain degree, and then you shoot across and obtain both hips. And some people, I think Anil Ranawat says, put your four fingers between the two hips, and that's a good profile. But of course, everybody's fingers are gonna be different size. So there's just no standardization. So I do get it, I evaluate it, but I think it is one of those things where you're also dropping the center edge angle just straight down. There's no ischium to draw your perpendicular from. So there's a lot of variability in that, but getting a sense of where you think the anterior coverage might end, estimating it with a lateral center or an anterior center edge angle measurement. And then as far as the CT, I think that's where being able to rotate the hip around will allow you to see areas of focal undercoverage that may not be clear on a two-dimensional x-ray. Also, the acetabular aversion measurements, which are often obtained at either the 12 or one o'clock position, two o'clock position, and three o'clock position on the axial slices, will give you a sense of whether there's significant anteversion, retroversion, focal undercoverage of the hip. You wanna talk a little bit about assessment of femoral aversion. So I know, I remember seeing a patient that had gone to Vail and had gone to New York and all and had imaging in both places. And the femoral aversion was off by about 15 degrees by their different radiologists. And I think the CT is probably more accurate than MR because of the acquisition times. But you wanna talk about when do you get femoral aversion assessments? Do you do it on all your patients? Or actually, we'll ask the panel. Do you get that on all your patients or do you only get that for specific individuals? And again, are you doing it off the CT or off of MRI? So. For our MRI sequences, we'll ask the radiologist to go to the distal femur and just get like one image of both sides. So we'll get, anyone that gets an MRI at our facility will get femoral aversion measurements. But if we're really trying to scrutinize if the patients have like an acetab, sorry, a femoral-sided abnormality, then we'll get a CT scan. Yeah, same thing. We always get distal cuts on our MRIs to look at the version on everybody. You know, I had a question about the, Mark, about the use of Sharpe's angle for borderline splastic. Do you use Sharpe's angle? Because in my hands, actually, it's an old measurement that John Charley used to use for his hip replacement. This is a good paper in 1973 in Core. John Fagan, well-known sports doc, was with John Charley. They wrote a nice paper about the use of Sharpe's angle. Do you use that in your assessment? So I do actually measure that. I have a grid that I use when I look at new patients, and it is one of my measurements. I think I've fallen more towards the tonus and the LCEA, but it's listed on my intake. So I take a look at it, too. Yeah, like in my hand, sometimes I'll have a normal center edge, but my Sharpe's gonna be like 43, 44, 45. In these patients, sometimes I won't do hip scopes on them, actually. So it's useful in my hands. Yeah, like I said, I think we don't do a great job of assessment because there's so many different things you can measure, and a lot of people just rely on the AP pelvis and try to measure a lateral center edge, and I think there's so much more to it that we're not really getting. But before we get to your question, so Andrea, the inversion measurements at your place, is that a routine or not? Yeah, so in my practice, I get a low-dose 3D CT scan on every patient that's getting a hip surgery, and there's some controversy about that. People say they don't get it on everybody. I still get it on every patient. We've acquired a low-dose protocol, which is about the same as getting two or three x-rays, so I worry less about the radiation exposure. And in that, you get a distal femoral cut, and we have started to get a distal tibia cut, too, to look at the tibial version. So that's the advantage of doing the CT scan. I'm happy to share that low-dose protocol with anybody who wants it, because that's something that you can apply to your institution as well. But in many cases, I will often remeasure the femoral version myself based on those CT cuts. Yeah, I mean, so I get, same thing in our place, and this would be probably one of the greatest takeaways, is that all the MRs that are done for the hip at Stanford are protocoled, and they all include distal femoral cuts to include the femoral version, though. Again, if you really are concerned about femoral version, I think a CT is better, because the faster acquisition time, the foot doesn't move as much, and you can probably get a more precise measure. But we always had the concern about the amount of radiation that they were getting, especially for young individuals. So I think these low-dose protocols, I think, can be very, seem to be a better, safer alternative. So, yes. So, thank you, those are great talks. So, when I look at these patients, very frequently I'll see capsular defects on their post-arthroscopy MRI. They're typically not multi-centimeter defects, they're typically smaller defects, and it's very challenging for me to distinguish whether that's symptomatic or not. Is there a particular symptom set or physical exam findings that push you to, this is a capsular problem versus something else? Yeah, that's a good question. So, usually from the history, a lot of these patients will tell you when they sit, they'll have pain interiorly. What I do is on my exam, I use ultrasound in my clinic almost on every patient now. And what I do is I'll extend, if I see something, even a small defect on the MRI, I'll extend the hip, externally rotate it to see if there's any, and you can see, visualize a capsule, if there's any translation. Then I'll move it slowly in flexion, rotate at the same time, and I'll see if that small defect, and also the location of the defect is very important. Interiorly, where the psoas is, can be a huge problem, even if it's only a few millimeters. So, the size of the defect is, sometimes these small defects, you'd be surprised. If they're very anterior next to the psoas, sometimes they'll have a communicating bursa. 15% of cadavers will have a communicating bursa. So, you have to differentiate that, but if it's even a small defect right next to the psoas, and they're symptomatic, when I do the revision, I'll be very, I'll look for it. For me, I look at it as for instability, because again, because you've got that defect, you oftentimes have a loss of your suction seal, and because you have loss of negative pressure maintenance in the joint, as well as the fluid. So, I think if you do look at a series of instability tests, I think you might find that they'll be symptomatic at the instability tests. So, in that scenario, I think Shane did a couple studies on capsular defects, symptomatic patients that had closure was 7.5%, I think was the number you had. So, I mean, it's not infrequent to see those, and see even more in those where the capsule isn't closed, but I look at the instability tests to tell me if that's part of the symptoms. Would you agree with that, Mark, as well? Because I know you're, yeah. Yeah, I'll tell you, for me now, I'm more aware of it, because I'm surprised how better they get with just closing that defect. So, even the small one, keeping a location. Yeah, a couple points I would make. One, for me, clinically, I think one of the pearls that patients, or what I've kind of learned over the years, is that patients with, like, instability, like, they're usually worse off after the scope than they were to begin with. And so, if their pain is significantly worse, if their function is actually worse than where they started, to me, that's always a sign that they're probably unstable. The other point I would make is that, even though the defects look small in MRI, I feel like the MRI is, like, underestimated. And a lot of times, like, when you put the camera in the hip, you'll notice that, you know, you might have that far medial defect where you're getting communication with the iliopsoas. And oftentimes, like, there'll be an extensive amount of, like, thinning of the capsule, even though there's not, like, a frank defect that basically is not substantive. So, if you're clinically suspicious and there's just a small defect, I mean, I think a lot of times it's actually probably bigger than what we're seeing on MRI. And I would just add, you know, I agree that the patient presents with more instability-type descriptors of pain. And so, basically, they hurt all the time. They can't get comfortable. So, a little bit different than our typical impingement symptoms. And I think this just echoes the importance of getting an arthrogram in the revision setting because you may completely miss that defect or that, you know, arthrogram bloom if you don't have the arthrogram in the revision setting. Thank you. Kind of going back to the morphologic analysis, I've had some patients where, you know, on the APX-ray, I'll measure the lateral center edge angle. It'll be around 18. So, I'll classify them as borderline. But then, you know, I'll also do the low-dose CT protocol, put it in HIP-MAP, and then that'll tell me closer to, like, 23, 24. Is that, like, a false sense of reassurance, or how should we reconcile that? So, I think X-ray is your gold standard. And the reason that CT scan measures higher is there have been a couple studies on it. But, basically, what happens is, especially in that upturned sore seal, the CT scan goes to the most lateral edge of the bone. But that may not be actually articulating with the femoral head. And so, that's where the X-ray will allow you to see where that most lateral edge is. So, I definitely consider what the center edge angle of the CT scan is, but recognize that often it's going to give you a higher number because it's taking slices and doesn't recognize where, you know, the most lateral portion of the sore seal is. Thank you. Which is an interesting thing, because patients come in with an MRI and no X-rays, and they don't, and I say, no, I need to get X-rays, and they look at me sideways. Why do you need an X-ray? Because you got an MRI. But, exactly, you know, all our measurements are based, actually, off of X-rays. And, again, can't stress enough, as Andrea had said, you know, it's got to be, the X-ray's got to be right. It's got to be not rotated. It's got to be one to three centimeters from the tip of the coccyx to the center of the pubic symphysis and all that, because that's how all those lines were measured, right? It's not measured off of an AP hip. It's measured off an AP pelvis. And with the divergent beams, it's the relative relationship with the different lines that are critical for that. I have a question. How often do you use your lumbar spine stiffness as a gauge for your PAO? Sometimes, like in hip replacement, you'll have a patient with a stiff back, and they'll have this anterior, on the coverage from the back. How often do you use that for your planning? Because sometimes it can cause, you can have a center edge of 23, and they need a PAO because they can't compensate with their pelvis. Yeah, the hip spine syndrome is something that I think we, in hip preservation, are far behind hip arthroplasty. So they've come up with some very interesting anecdotes on how that affects the hip. But I think that's where that standing AP pelvis is my best gauge, because that gives you the functional position of the hip, and that incorporates how the lumbar spine is articulating with the pelvis. Yeah. I'm curious how you guys assess the results. We've talked about the diagnostic arthroscopy, but if you have a capsular defect, and if somebody doesn't get better, is that because the fluid left the joint, and they're not getting the results of that, or is that because maybe it's an extraticular problem? So sometimes I struggle with trying to figure out a negative response if they have a capsular problem. So the question is, if you're seeing the capsular defect? No, like a preoperative diagnostic injection, and if the fluid is potentially not staying in the joint because of a capsular problem. So I mean, I think that does occur. I mean, you do see that, and I think, differentiate that from people, 17% of people have a connection between the joint and the iliopsoas versa, right? But take that as a separate view. Somebody that might have a defect, either traumatic or for whatever reason, again, I think it may affect the ability for suction sealants. I'd look more towards instability as a potential, but let me leave it to the panel and ask Gav. Yeah, I would just say that that is something we also see in dysplastic patients. So they have a non-response to an injection. And so again, we're maybe clumping the capsular defect group into more of an unstable group. I would, just as a caveat, we just published this paper where we looked at a bunch of patients of mine that had MR arthrograms that had gadolinium and anesthetic. So I figured why give them two shots. The gadolinium can block the effect of the anesthetic. And we then would take, and patients that I was sure the pain was coming from inside the joint, send them for an ultrasound guided or even a floral guided injection without gadolinium, and it got rid of their pain. And it's a real thing that even though it's 110th of 1cc or whatever gadolinium they put in, that can be very noxious to some individuals. There are people that are gadolinium sensitive. So we don't use gadolinium anymore. We just use the anesthetic as our contrast. Just like in the old days, they used to use saline as a contrast. It's not as good a contrast as gadolinium, but it's certainly good enough to be able to make that determination. I typically use, I do an air arthrogram for our injections in a post-op setting. And oftentimes if you have a well-healed capsule, typically the arthrogram is gonna look like a native hip. And so that's one of the things I look at and I use it as a diagnostic information as well. But if you do get like lots of either gadolinium or contrast or air extravasating outside the joint, I think it's just another indication that the capsule's deficient and there might be clinical signs of instability. Sometimes with patients with chronic flexor tendonitis, they'll give injection on the flexor. They'll inject the joint, the fluid, the lidocaine will extravasate, so they'll focus on the psoas. But the reality, what I found is sometimes when these people with tight, tight psoas, they'll erode through their capsule actually sometimes, and then the diagnostic injection in the joint is useless. So watch for these flexor tendonitis because often the underlying cause is actually concomitant with the joint. In all actuality, just to talk about part of that, I mean, I think the iliopsoas is an important anterior stabilizer to the hip. So for somebody who has micro instability and it's an anterior translation issue, I think the psoas is positioned to try to help resist some of that anterior translation. So I think the psoas gets overused in people that have micro instability, if you will. And so, as Mark said, there's the connection between the two that when you have a defect particularly. So when we do an MR arthrogram and we see the anesthetic, I always look to see, well, did some of that anesthetic go around the iliopsoas as well? Because you can't necessarily differentiate between the pain generator being the psoas or the joint, but you gotta be concerned that when the psoas is flared up, one of the reasons it may get flared up is because it's an unstable joint. Yeah, and in this plastic patient, they'll have labile tears, they'll have chronic psoas tendonitis, and they'll focus on the psoas. Meanwhile, the patient probably would benefit from a PAO. Thank you. One of the things we've seen is so-called dynamic instability. So we get standing and supine AP x-rays, and sometimes you can see normal coverage on one and then undercoverage on the other. Do you guys routinely get both standing and supine x-rays? And if so, how do you manage a patient that has a normal looking x-ray on one but then potentially undercovered on the other? Hershey. I typically only get the standing. And again, my thought is that it's functional. It's how they're standing and moving. And if they're supine, depending on the amount of lumbar lordosis they have or how much gluteal mass they have, it will change the position of their pelvis. And so I defer to that, but that's an interesting thought. So I would pay attention to the standing. Yeah, I do too. I just get the standing. My PAO partner does standing and supine. And I think the open hip surgeons like the supine because they're able to replicate that in the OR better. But I think he also prefers the standing too because of what Andrew's mentioning. And Shane, what I do in the OR is I actually just match my operating room table to the standing. So the standing AP pelvis up on the wall and I'll airplane Trendelenburg, reverse Trendelenburg to get the patient on the table to match the standing. So I don't need a supine x-ray. Mark, are you supine or are you standing? So I had Michael Leuning spend time with me in Vail and he was really focused on the supine x-ray. And I've been using that, but I'll use both actually. But my initial protocol is supine. Yeah, and so I was supine for the longest time. A lot of influence from Mark and Michael in all reality because I thought it was always easier to be more precise if you will on getting a good AP x-ray. But about a year ago, we switched to standing as well. But I don't do both. It's hard enough for me to convince the California people to get three views around the hip because they're worried about the radiation. They're not worried about flying in New York and the radiation to get from that, but they're worried about the radiation from an x-ray. Yeah, quick question. All these were great presentations. Whoa. So a question that I have that I would like to ping you guys would be what are your feelings on Coxivara being a cause of impingement and is it worth correcting? So I'm very conservative with femoral osteotomies including to correct Vera and Velga. So I will often attempt either PAO, hip arthroscopy, whatever else first and see if the patient fails. I think especially Vera going to Velga, you have a little bit better chance of healing than going from Velgas to Veras. But patients don't like the differentiation of the tension on the abductors. And so I find that if we can avoid any of the osteotomies, it's better. Actually, that's a good point. If you go to correct Vera sometime, I just saw a patient recently, she had a dysmorphic, her ilium was dysmorphic. She was more in Velga and she was really weak on her gluteus medius. And someone wanted to do a Vera osteotomy on that patient. And I think if you over correct a Veras, you can cause some problem with the abductor. So because that's the abductor arm is better with the Veras. So they'll complain about weakness in the abductor sometimes. So that's something to take into consideration. We don't perform. I have Dr. Mount in my office. And we rarely would do a Veras correction. Shane, you got anything to add on that or? No, I guess the only thing I would mention is that I think along those lines, recovering from like an acetabular sided osteotomy generally I think is better tolerated for patients than a femoral side. And so I think that's why the open surgeons prefer to correct through the acetabular side. So whether you're doing versional issues or various valgus, I think for some reasons patients have a harder time recovering from them. And one other point is that often with coxa, Vera, or Velga, they're symmetric. So if you correct one side, you've just bought the patient the other sided surgery as well. I kind of do the relative lengthening, if you will, by trying to take down some of that CAM arthroscopically and see how they do with that as opposed to trying the osteotomies because yeah, they've had the same experience. But again, the Vera, you worry about the impingement. People we don't talk about nearly as much. The Valga, I worry about the instability as well because I think the higher degree of valgus you have, the lesser, well, the more dysplastic acting some patients will act even with a more of a center-edge angle than others with a regular neck shaft angle. So we're beyond time. Thank you all for your questions. Thank you for the great talks, Shane, Mark, and Andrea. And hopefully this was worth your while. Thank you so much. Have a great meeting. Thank you, Mark. Thank you.

hip stability

diagnostic techniques

imaging techniques

dysplasia

capsular defects

dynamic instability