All right, we'll talk a little bit about femoral and acetabular retroversion and why these things might matter. It's kind of fitting that the acetabular retroversion paper got a lot of excitement from the audience on the app. So here's my disclosures. So we know that well-performed hip arthroscopy has tremendous potential to help patients in terms of satisfaction and return to sport. We're going to talk about some anatomic considerations with regard to acetabular version and femoral version and also how that relates to sub-spine impingement. So there's lots of considerations when we're talking about anterior coverage, posterior coverage and sub-spine. So first, you need to know where your anterior and posterior walls are. You need to know what sub-spine morphology is with the classic type 1, 2, and 3 as shown here. And you need to appreciate that femoral version has a wide range of discrepancy throughout the general population and should be measured with a cross-sectional imaging like this CT scan. Acetabular version, when it's low, we call that retroversion as was just demonstrated in the paper. And we worry about anterior impingement and posterior instability in these cases. So again, as we all know, the crossover sign, the posterior wall sign, and the ischial spine sign are what you need to diagnose true or global acetabular retroversion. So we can cross over here, positive posterior wall sign and a positive ischial spine sign. And most comprehensively treated with the anteverting PAO in many cases is the female patient we treated two and three years ago on both hips here. We also need to recognize that you should correct other things during PAO surgery as well. It's our preference to correct labral tears during a PAO surgery and also head and neck offset. And this is demonstrated by this paper in JBJS that positively impacts the joint reactive forces and joint mechanics after surgery. And the professors in Bern, mostly Moritz Tenass and Klaus Siebenrock, have demonstrated that the most durable long-term outcome for patients in terms of survivorship, especially after four years, is an anteverting PAO for acetabular retroversion. However, I think most acetabular retroversion cases are treated with arthroscopy in the United States. So some cases that's fine. So we really need to define what those are and figure out where our threshold is to refer patients for PAO. We presented this data last year. There's better outcomes in males with retroversion, better outcomes in athletes, and those with significant sub-spine deformities. So in these cases, our preference is to perform an anterior rim trim, a sub-spine resection, which can be done through a pericapsular window as being demonstrated here in her right hip. This is a pericapsular window through the proximal capsule and a little bit of the direct head of the rectus. And you can perform a well-done sub-spine resection, as shown by the false profile views in the bottom left-hand side of the screen here. Low femoral version, on the other hand, this is the patient that walks with their knees out, that walk with their toes out. Every time you have a suspicion for low acetabular retroversion, if they have bad internal rotation and inflection, you should look at the sub-spine morphology on the acetabulum, because Professor Lerch has showed us that the contact areas drastically vary with the amount of version in the femur. So low version femur is going to contact the sub-spine, the anterior acetabular rim, and it's going to impinge on the femur way distal on the neck. So you need to know if you have a low version femur, you need to burn this basically right-sided picture into your mind. You need to do a resection way up onto the sub-spine and down onto the distal femoral neck in order to correct your impingement adequately. This is a case of a five-degree anteversion male football player with a type 3 sub-spine from a prior injury. You can see the distal neck impingement, fairly large cam, and type 3 sub-spine deformity treated with arthroscopic camber section and osteochondroplasty. Conversely, instability can be a problem if the acetabulum is pointed forward. This is a 20-year-old female Division I volleyball athlete with borderline hip dysplasia who's been complaining of hip instability and when you get her on the table, she has 50 degrees of internal rotation inflection, which is excessive for people who do a lot of hip scopes and FAI work. You can see by her anterior and posterior wall, she's drastically undercovered anteriorly. And for the last three seasons before her surgery, she was treated with a Spica wrap to promote anterior hip instability protection by her team's athletic trainer. She's the one doing this block here on the far side of the screen. So in her case, she walks with her knees in. She complains of anterior instability. She has low anterior coverage. You really need to consider femoral version and acetabular in terms of combined version. This diagram could be helpful, and this is the one that applies to her. This is a very undercovered hip anteriorly in acetabulum and a high anteversion hip. She has 35 degrees of anteversion in the femur with a combined McKibben index that's very high and leads to anterior instability and posterior impingement. So you put that together with her down view, she has a very small sclerotic cam. She has almost no anterior coverage on her false profile view. And her 3D CT scan, you can almost see her ligamentaries because she's so undercovered in the front. There's a lot of different ways to treat this. I think most of the time, this athlete might be treated with an arthroscopy alone. However, there's other treatments. I think Jeff Nepple might recommend a femoral osteotomy or a PAO or isolated arthroscopy. Our preference was to perform a PAO to increase the lateral and anterior coverage along with a labral repair and head and neck offset correction performed at the same time. She returned to unrestricted volleyball at seven months. You can notice the difference, although some people may think it's subtle, a pretty large correction in the anterior coverage after PAO surgery. So in conclusion, global acetabular retroversion of PAO should always be considered. Arthroscopic treatment may be safest in males, athletes, and those with a prominent subspine. High acetabular or femoral anteversion, you should expect instability, especially if those two are combined. And low femoral anteversion or femoral retroversion, just know where to do the resection. It's high up on the subspine region and just on the femoral neck. So thanks for your time.

femoral retroversion

acetabular retroversion

hip arthroscopy

sub-spine impingement

periacetabular osteotomy (PAO)