Excellent talk. Thank you, Guillaume. Next up is Dr. Andrea Spiker from the University of Wisconsin, talking about her indications of PAOS. Thank you. Thanks to Anna, and I'm glad to be here. Here are my disclosures, none of which are relevant to today's talk. So today I'm going to talk about the indications for periacetabular osteotomy, patient workup, surgical approach, and then postoperative outcomes. So the classic indication for a periacetabular osteotomy, or PAO, is hip dysplasia, which is diagnosed on radiographs with a measurement of the lateral center edge angle that's less than 25 degrees. We can also subcategorize dysplasia into severe, mild, moderate, or borderline dysplasia as well. While we use the lateral center edge angle most often, there are numerous other radiographic findings that might indicate a patient has hip dysplasia. When I'm doing radiographic measurements, I like to use the standing AP pelvis X-ray. And the reason is that a supine X-ray can give you a false indication of a pincer lesion, acetabular retroversion, and can actually overestimate the lateral center edge angle by 2 to 3 degrees. So in my practice, I rely most on the lateral center edge angle measurement and the tonus angle. When you're measuring the lateral center edge angle, it's very important to pay attention to where the lateral most aspect of the sore seal is. Here, the sore seal is upturning and therefore not providing any contact with the femoral head. So if you measure a center edge angle to this point, it's going to be very different than if you measure it to this point. And here's an example. On the same X-ray, I've measured the lateral center edge angle on three different locations. I would say the image on the right is the appropriate way to measure the center edge angle. And you can see there's almost a 10-degree discrepancy between where that lateral line is drawn. But still, the lateral center edge angle is probably not enough. In upwards of 39% of all hips with a normal lateral center edge angle, they are actually moderately dysplastic by some other measure, including the tonus angle. If a tonus angle is greater than about 10 degrees, that's an indication that the hip might be unstable or dysplastic. And in some patients, you may have to obtain advanced imaging, such as 3DCT, in order to appreciate how undercover the femoral head is. Now here, it's also important to keep in mind that dysplasia is a radiographic diagnosis while instability is a clinical diagnosis. So in patients with borderline hip dysplasia, or even those with a normal lateral center edge angle, if they have an indication for clinical hip instability, a PAO may still be the right answer for them. Now sometimes, it's difficult to discern dysplasia from other hip pathology. And oftentimes, patients will present with similar findings of hip impingement. One thing that can set them apart is they tend to have more of a muscular fatigue pressure. So they'll have pain with extended periods of standing, sitting, walking. And there's also a positive what we call high heel sign. So if they put high heels on, that exacerbates their pain because the pelvis tilts and undercovers the hip joint. In all hip patients, it's very important to assess for hypermobility. If a patient score is greater than 4 to 6 on the Batten score, this should clue you in that they might have hip instability due to capsular laxity. Now there are a number of clinical exams and provocative maneuvers that can help you discern who's dysplastic versus who has impingement. And so as far as the approach, if you've decided that somebody has dysplasia and they need a periacetabular osteotomy, this surgery is performed through multiple osteotomies, which allow us to completely separate the acetabulum from the rest of the pelvis. We can then take that acetabular fragment, rotate it. And this provides a more congruent joint and more lateral acetabular coverage. We perform the periacetabular osteotomy through a small bikini incision. And this allows a muscle-sparing approach that gives us access to the pelvic bone. Now whether or not to add a hip arthroscopy to a PAO is actually a controversial topic. So almost every dysplastic hip is going to have some sort of intraarticular pathology. But in this series, in those patients who had intraarticular pathology and had a PAO alone, only about 27% went on to need a hip arthroscopy at some point after the PAO. So it's possible that simply reorienting the hip socket and therefore correcting the underlying pathomechanics is actually what resolves patient's symptoms and pain. Now my personal approach is that if a patient has intraarticular pathology, I perform a hip arthroscopy at the same time as a PAO. Because I'm the surgeon performing both portions of the procedure, I do it on the same table with the same prep and drape, start with the hip arthroscopy, and then proceed directly to the periacetabular osteotomy. Now we know that if you leave acetabular dysplasia untreated, it will result in osteoarthritis. We also have good data now that shows that if you do a PAO on a dysplastic hip, this actually reverses the natural history of hip dysplasia and prevents osteoarthritis from occurring. 10-year survival rates have been reported up to 95%, 15-year survival rates up to 92%, and the complication rate after PAO is relatively low at about 1%. And a vast majority of patients are getting back to their preoperative or higher activity levels at midterm follow-up. And PAO in even borderline dysplastic patients has very good results. Postoperative recovery is not too dissimilar from hip arthroscopy. It's a slightly longer duration of weight-bearing restrictions. I use chemoprophylaxis to prevent DVTs. And then the PAO, in my practice, most patients are going home post-op day one, so it does require an overnight stay. So in summary, the periacetabular osteotomy is indicated for hip dysplasia. And it may be indicated for even those patients who have relatively normal acetabular bony coverage but have indications of clinical hip instability. The PAO is a very powerful, very effective surgery that actually reverses the natural history of hip dysplasia and can prevent osteoarthritis. Thank you.

periacetabular osteotomy

indications

hip dysplasia

lateral center edge angle

clinical hip instability