I'd like to thank the Anna committee for the opportunity to present on this topic. This is a very, very important topic as we start to determine who the best people are for indicating hip arthroscopy surgery. So in this topic, we'll talk about imaging studies, x-ray, MRI and MRA, as well as other advanced imaging studies, including ultrasound and how it pertains to proper indications and diagnosis. Here are my disclosures. None are pertinent to this talk. So we've learned a lot about femoral acetabular impingement over the years, and this is one of the landmark papers from Professor Gans that really helped us understand the pathomechanics of how FAI contributes to degenerative arthritis. I won't go into this too much, other than just highlighting how critical this paper was on the tremendous knowledge that we've gained on FAI over the years as it pertains to research. This paper, the Warwick Agreement on FAI is probably the best summary on what our evidence based approach is for managing patients with FAI. I actually give this to all my patients I see in the office with FAI syndrome as a very good educational tool. So FAI syndrome is a motion related clinical disorder of the hip with a triad of symptoms, clinical signs, and imaging findings. And it represents the symptomatic premature contact between the proximal femur and the acetabulum. Specifically, what this refers to is, this is a visualization of how a CAM lesion abuts with the anterior superior labrum. You can see that there really is a convexity of the femoral head-neck junction, applies a shearing force, which is what causes early cartilage damage, and also anterior superior labral tears. Once again, the CAM lesion can cause early cartilage damage as shown in this sequence, both from the labrum as well as the outer surface of the cartilage. We know that most cartilage lesions occur in the anterior superior aspect of the acetabulum, which further supports the pathomechanics that were outlined by Professor Gans and other authors up until this point. The cousin of CAM-dominant impingement is pincer-dominant impingement, and that's where you have a little bit of extra bone on the rim of the hip socket or the acetabulum. And what happens is as you flex the hip, there's a contrecoup levering effect in which the femoral head-neck junction actually functions as a fulcrum, and there's a wear pattern in the posterior aspect of the acetabulum. So we know that FAI can lead to labral tears, and most frequently, these are in the anterior superior quadrant of the acetabulum. Labral tears rarely occur without some type of bony abnormality as been shown in various works. So from a diagnostic standpoint, how do we arrive at the right patient that we want to operate on? That's gonna be the focus on today's talk. There are many causes of hip and groin pain, and one of the keys to your job in the clinic is to identify which patients have intraarticular pathology as these are going to be the most likely to benefit from your intervention surgically. So the keys to this are knowing your anatomy, doing a thorough history, doing a good physical exam, and focusing on imaging. So Brian Calley gave us a very good idea of a layered understanding of the hip joint, and that's depicted in this slide. And really, there's the ossochondral layer, the inner layer, and the dynamic layer, and then the neural layer. And really, we want to focus on the intraarticular pathology. The hip is a ball and socket joint that has a very significant femoral head cartilaginous structure, including, and on the socket side, there's a lunate surface that is very characteristic, and this is where the majority of the weight-bearing cartilage lies. Up close, the acetabulum has a stellate crease, which is typically at the 1230 position. There's a psoas U, which is typically at the anterior-most position, and then there's a caudaloid fossa. The labrum deepens the socket and provides a fluid seal. I really didn't believe in the suction seal of the hip. Mark Philippon would often talk about it during our fellowship, and I really didn't believe it until I dissected the hip, as shown in this video, and I saw it up close and personal for myself. So there really is a very powerful suction seal, and when you take out the labrum, that goes away and it can be partially restored with the labor reconstruction. So from a diagnostic approach, we really wanna focus our imaging on getting a three-dimensional visualization of the hip joint and understanding how that three-dimensional visualization interacts as we do our physical exam. So the imaging is very, very important. The Warwick Agreement recommends an AP pelvis, as well as a lateral femoral neck view. It recommends that we quickly be able to assess the joint space, identify CAM or pincer morphologies, and then utilize advanced imaging for understanding the cartilage, the labral quality, as well as other bone pathologies. Here's an overview of some of the types of pathologies and morphologies that you may visualize on standard AP imaging. So on the left-hand side, you can have overcoverage. In the middle, this is a more normal-appearing hip with a small crossover sign. And on the right-hand image, you have dysplasia. And it's really critical that we assess all of our radiographs very precisely and do it in a very systematic way so that we can exclude out bad actors for hip arthroscopy. Overcoverage of the hip often takes the form of pincer lesions, as well as coxa profunda and protrusioacetabuli. Ways to assess acetabular retroversion involve the crossover sign, which is essentially a sign of acetabular retroversion. And that's essentially when you have a crossover between the anterior wall of the socket of the acetabulum, as well as the posterior wall. Similarly, the femoral head and the floor of the acetabular fossa should be lateral to the ilio-ischial line. This also indicates a more normal-appearing morphology. If it's medial, that's when you have a global deformity of the pincer. Here's an excellent animation that my good friend Jorge Chala has put together, essentially kind of showing how we measure the lateral center of jangle, the tonus angle, as well as other measurements. Essentially, a lateral center of jangle by less than 20 degrees is considered to be dysplastic. You have to use a very significant amount of caution when indicating those patients for isolated hip arthroscopy. Similarly, a tonus angle greater than 10 is considered to be dysplastic. With regards to dysplasia, we know from a variety of studies that a lateral center of jangle of less than 20, anterior center of jangle less than 15, a break in Shenton's line, or a lateralized femur, all of these are poor predictors for isolated hip arthroscopy. In many cases, these are contraindications to isolated hip arthroscopy because we cannot add bone. Many of these patients we should indicate for concomitant PAO with hip arthroscopy procedures versus a total hip replacement if chondral degeneration is already present. On the CAM side, standard AP x-rays of the hip, which are commonly done by primary care physicians or non-hip preservation orthopedic surgeons, typically will miss the CAM lesion. A done lateral x-ray, which is typically with the hip in a slight amount of abduction, flexion, as well as external rotation, is necessary in order to get a good view of the femoral head-neck junction at the location with which the impingement actually occurs. So the alpha angle is calculated by essentially taking a spheric measurement of the, or assessing the sphericity of the femoral head. The normal angle is about 42 degrees. Typically, CAM lesions will have greater than 50 to 55 degrees of the alpha angle. So x-rays and advanced imaging are taken in conjunction. In my office, we typically will use the x-ray to get a good sense of the joint space, as well as the radiographic measurements of CAM and pincer lesions. On the MRI and the MRA, the MRI is typically done to assess for labral tears, avascular necrosis, cartilage pathologies, loose bodies. And I use a CT scan in some cases to assess for locations of os acetabuli and global deformities, as well as to guide resection in cases of severe FAI. In my office, the MR arthrogram is typically the ideal study as it gives the best visualization of labral pathologies. In some situations, and some radiologists actually prefer an MRI instead of an MR arthrogram. That's a debate that continues to go on. There is always a benefit of not doing an arthrogram as it sometimes causes an irritant to the hip joint, but regardless, it's a very helpful tool. CT scans in my office are typically done to assess for preoperative planning purposes, especially in situations of severe FAI. It also gives a very good roadmap of the femoral version, if that's ever in question, and if we're considering a femoral osteotomy of some kind. So one pearl that I'd like to leave you all with is to get serial x-rays on some of your older patients, specifically patients over 45, as sometimes there's a biochemical component of osteoarthritis that is hard to pick up on a single static x-ray. As an example, this is a 59-year-old female who was referred to me from one of our physical therapists in the area for persistent pain of her hip six months after a hip arthroscopy that she had somewhere. And as you see on this x-ray, she does have some signs of dysplasia, but for the most part has good joint space throughout. On exam, she had quite a bit of severe hip pain. She wasn't responding well to physical therapy. And so one thing that we did was to get a set of serial x-rays. And a simple x-ray, a serial x-ray two months later showed complete loss of joint space. So essentially we were seeing her hip present to us as it was developing a severe degenerative pathology, both from biochemical and biomechanical means. Similarly, a lot of other physicians have also commented on the importance of indicating patients with good joint space. This is an article by Dr. Ben Dome that was recently published in which he looked at the first group of patients and the second group of patients, meaning the first 200 cases that he did as well as the last 200 cases that he did in his career. And he noted that part of his, the first group of patients had significantly more patients with tonic grade one degenerative joint disease. So in other words, he was having a higher arthritic population when he first started out and then this gradually kind of tailed off. And this is one of the things that he attributed to his improved clinical outcomes as his career progressed. So probably the biggest pearl is, you always want to assess joint space on a standing AP radiographs. And really this is critical to making sure that arthritis is not already advanced. Because if you intervene when the biochemical and the biomechanical cascade of degenerative joint disease or osteoarthritis is starting to take hold, no matter how perfect your surgery is, you're not going to have a good outcome. So in my practice, I ideally want to have greater than three millimeters of joint space with no subchondral cysts. This ensures that we're operating on no higher than a tonic grade one patient. And so the literature says you should aim for two millimeters and above. In my practice, it's three millimeters and above. So another really useful diagnostic tool are ultrasound guided intra-articular hip injections. And the pros to this is you get real time diagnostics. It's easy to learn. It's very efficient. It's very cheap to the healthcare system and the patient overall. And it really gives us a lot of insight early on in terms of what is coming from an intra-articular cause versus an extra-articular cause. The studies show that a response to a diagnostic injection in many cases has a higher diagnostic utility than even an MRI or an MR arthrogram for many patients with hip pain. This is a paper that recently we presented at the Academy that showed the tremendous cost benefit of doing an intra-articular injection in the office with ultrasound versus a hospital using a fluoroscopic guided system. So the pearls for ultrasound injections are you want to get comfortable with your anatomy and the ultrasound machine and know where your nerve aster structures are. You want to know that when doing these injections that the hip capsule is very thick, in many cases, one centimeter. And you also want to position your patient so that you can easily access their ASIS as well as the intra-articular aspect of their hip. So when I do this, I start out by doing a transverse view of the femoral head, and then we gradually place the ultrasound probe in line with the femoral neck to get a very nice profile view of the femoral head-neck junction. Avoiding the iliopsoas and being just lateral to it, a spinal needle can then be brought in and placed directly onto the femoral head-neck junction, at which point you'd know that you have quite a bit of space to inject into the capsule, or into the intra-articular space underneath the capsule. Once again, it functions very well, even in larger patients. So, in summary, a proper diagnosis and patient selection is key. Get serial radiographs on older patients with questionable early osteoarthritis. You want to differentiate intra-articular versus extra-articular pain. And then location, location, location. The hip pain that is intra-articular typically has some level of pain that's coming that radiates to the anterior aspect of the hip with the distribution of a C-sign. Thank you very much for this opportunity. Please contact me if any questions.

hip arthroscopy surgery

FAI

diagnosis

imaging studies

patient selection