PAO is the best option for hip dysplasia. My disclosures are not relevant to this except from CIHR support for some of our research. As you've seen in the last few minutes, there's been exposure of surgical techniques for hip preservation surgery. It's often difficult to decide which is the best option. When we talk about dysplasia, we always talk about the worrisome of hip arthritis progression. These are defined parameters, which clearly show that there's a temporal sequence to degeneration. But what is really the natural history was first described by Viberg, where the term borderline dysplasia was first coined. I would like to bring your attention that this was in asymptomatic hips at the risk of arthritis. So I'd post you that the term borderline is not appropriate in defining the symptomatic hip. The other issue with the term borderline, there's a plethora of definitions of what exactly is borderline, and Chris alluded to that in his talk. And when you don't have the right diagnosis, how can you really compare your results to one another? So can we agree what dysplasia is? And I think if you can agree on diagnosis, then you can agree on treatment and have a more predictable outcome. So what is dysplasia? It's an abnormality of development, pathology leading to alteration in size and form. It was first recognized in the hip in the pediatric population as a form of instability, as the leading patho-mechanism. So dysplasia is a problem of instability. Chris again stated that we don't fully know what the true parameters are. I would argue that we do know now by the work by Morris Tanis in CORE in 2015, where he really introduced a concept of anterior postural coverage assessment, moving us away simply from the Viberg angle or the Astaverda index. And these are the anterior and posterior wall indices that are very easily measured on the AP radiograph, defining both anterior and posterior coverage by dividing the extent of the anterior wall over the radius, and conversely for the posterior wall. And this is now part of our assessment for any symptomatic hip. And with that, you can define posterior on coverage or retroversion, which is a clear retrotorsion of the hemipelvis and not excessive anterior coverage. You can define anterior on coverage, where the hip can be corrected using the PAO, which provides corrections in three planes and providing appropriate coverage. If we look at the outcome of hip arthroscopy, I would say in dysplasia, as a standalone procedure, I would say the outcome is unpredictable. This is a paper by Joe McCarthy showing a 28% conversion to total hip at 2.5 years, regardless of the status of the cartilage. Chris alluded to this paper from the Boston Group, showing that 94% of these so-called dysplastic hip had a sign of radiographic dysplasia, as allowed below, and a mean follow-up of 2.2 years, no reoperations. I think we need to move to a more comprehensive classification, reflecting the three-dimensional nature of dysplasia, where we can subgroup them into a lateral coverage or gross instability, which is the classic one, a posterior on coverage or instability, where you can measure, which is the astab retroversion, and anterior coverage or instability, which often can be combined with extra-articular impingement. We've described this classification system and defining that into a flowchart using the lateral standard angle, as well as stability index, as well as anterior and posterior indices, and we're able to categorize our hips into three broad categories, demonstrating substantial anterior and intra-observer reliability. However, the classification was not perfect, so we felt that we need to add a different aspect to it to make more visual. So for the lateral coverage, I would suggest this, looking at Chris, and then you have anterior coverage deficiency, and then you would have posterior coverage deficiency, and with that, we have achieved substantial reliability. In conclusion, structural instability is really a problem within dysplasia. The term borderline should not be used, because it was really described for the asymptomatic hip natural history. The classification we presented provides, I think, a comprehensive aspect to our surgical management. I think microscopy has a role as an adjunct to PAO, and I think the best outcome is with optimal coverage. Thank you very much. Thank you.

hip dysplasia

periacetabular osteotomy

diagnosis

classification system

hip arthroscopy