Thank you and thank you for having me. I'm Andrea Spiker. I'm an open and arthroscopic hip and sports surgeon at the University of Wisconsin. Here are my disclosures, none of which are relevant to this talk. So as you've heard, borderline dysplasia is defined as a lateral center edge angle between either 18 and 25 degrees or 20 and 25 degrees. With hip preservation surgery, it's relatively straightforward to indicate somebody for hip arthroscopy when they have femorostabular impingement. It's pretty straightforward when they have frank dysplasia to offer them an open surgery. But the challenge comes with borderline dysplasia because we don't know whether arthroscopic or open surgery or perhaps both is the right answer. There are a number of series out there that show that hip arthroscopy can work in the setting of borderline dysplasia and Shane has just spoken to these. So in the next couple of minutes here, I'm going to tell you why we shouldn't do hip arthroscopy and borderline dysplasia and I'm going to try to hit on each of these points here. So first, there's controversy as to whether interarticular pathology even matters in the setting of borderline dysplasia. There's a really high prevalence of labral pathology in symptomatic borderline hips, upwards of 90%. And in this series, 87% of borderline dysplastic hips undergoing PAO had labral pathology, but only 27% subsequently underwent arthroscopy. So perhaps it's the reorientation of the acetabulum with correction of the underlying pathomechanics that actually resolves these patients' symptoms. If you're convinced the interarticular pathology is a problem, you can certainly do combined hip arthroscopy and PAO, and this is my preference. Now, the assumption that you can do a hip arthroscopy in borderline dysplasia assumes that all borderline hips are the same. We've heard a little bit about this so far, but there's a significant variability in where surgeons are measuring the lateral center-edge angle. So it's very important to understand where the sore seal is and where the lateral most aspect of that sore seal is. This upturn of the sore seal is actually not providing any femoral head coverage, so this center-edge angle measured here is going to be very different than if it's measured here. Even if you appropriately measure the lateral center-edge angle, it's often not enough. Up to 40% of normal hips as defined by a lateral center-edge angle are actually dysplastic by some other radiographic measurement, including the tonus angle. And now, even if you appropriately diagnose somebody with borderline dysplasia with radiographs, now the challenge is clinically defining them as an unstable versus stable hip. Dysplasia, remember, is a diagnosis based on radiographs, whereas instability is a clinical diagnosis. More recent literature has shown us that the characteristics of a borderline dysplastic hip are actually more similar to dysplastic hips than to hips with normal acetabular coverage. Here's an example of one of my borderline dysplastic patients, and you can see there are stigmata that are not associated with typical femoral acetabular impingement. There's a large flap of cartilage attached to the inferior aspect of the labrum. There's near complete detachment of the labrum from the acetabulum. And in this patient, I did first a hip arthroscopy and then a concomitant PAO. Now, you also have to recognize that not all hip arthroscopy is the same. So there are significant differences in hip arthroscopy patients who have labral repair and capsule repair in the borderline hip dysplasia setting compared to those who have an open capsule or unrepaired labrum. So let's go back to these reports that you can do hip arthroscopy and borderline dysplasia. We should probably emphasize that these were all done by a very high volume expert hip arthroscopists in patients with stable borderline dysplastic hips. Even if you do a perfect hip arthroscopy in a borderline dysplastic hip, there are certainly a very long list here of non-modifiable factors that can lead to a higher failure rate in that borderline dysplastic hip. Also, one of the reasons that people push for arthroscopy is they say that the PAO is very hard to recover from large surgery. I would say that, yes, we are osteotomizing the pelvis, but we do so through a very small incision and a muscle sparing approach. So pain is actually quite minimal. There are also significant consequences of choosing the wrong surgery. So we really need to take this decision very seriously. And I'd say that the outcomes are worse if you mistakenly choose hip arthroscopy. PAO patients who've had a history of prior failed hip arthroscopy have significantly lower patient reported outcomes after their definitive PAO. And there are some reports that hip arthroscopy prior to total hip replacement also increases your risk of revision surgery, periprosthetic infection, and aseptic loosening. There's also the possibility that these hips go on to rapid catastrophic osteoarthritis after hip arthroscopy and borderline dysplasia. This is typically reported within one year of surgery. So we know the natural history of hip dysplasia is osteoarthritis early. With the PAO, we can change that natural history by giving the patient a normal hip. And we can do so with excellent long-term survivorship, up to 92%, and a minimal complication rate. A couple of technical considerations for PAO and the borderline hip. I have a strict BMI max of 30. And that's because over a BMI of 30, patients have a significantly higher complication rate. And you can see the cuts here that we make are quite deep in the pelvis. We're doing a lot of these blind. And so soft tissue obstruction is a problem for technically performing the surgery. Here you can see the window through which we're doing the surgery and getting very deep down into the pelvis. Another technical consideration is that technically borderline dysplastic hips are an easier PAO than severe dysplastics. But you also have to be careful not to over cover those hips because you have more acetabulum to start with. So in summary, I would say don't try this scope in borderline dysplasia because arthroscopy is not addressing the underlying problem. And arthroscopy is less predictable than for other diagnoses such as FAI, can worsen symptoms, has a high failure rate, can accelerate arthritis, can result in poorer outcomes after subsequent definitive PAO, and perhaps after total hip arthroplasty. Whereas the peri-acetabular osteotomy has excellent outcomes and actually reverses the natural history of dysplasia. Thank you.

borderline dysplasia

hip

labral pathology

acetabulum reorientation

peri-acetabular osteotomy