Dr. Chris Tucker:
Welcome to your Arthroscopy Journal Podcast. I'm Dr. Chris Tucker from TSAOG Orthopedics and Spine in San Antonio, Texas, and the podcast's founding editor. Today on the podcast, we're discussing hip joint preservation. I'm excited to welcome to the podcast Dr. Matthew Kraeutler, an assistant professor at Texas Tech University Health Sciences Center. Dr. Kraeutler was the lead author on the infographic titled The Principles of Hip Joint Preservation, which was recently published in the July, 2024, issue of the Arthroscopy Journal. Matthew, congrats on a great infographic and welcome to our podcast.
Dr. Matthew Kraeutler:
Thank you for having me, Dr. Tucker. I'm really excited to be on the Arthroscopy podcast and I look forward to our discussion on this really interesting topic.
Dr. Chris Tucker:
Yeah. Appreciate you taking the time, Matt. So as you highlighted in the abstract to your infographic, the primary three factors involved in hip joint preservation are femoral acetabular impingement, or FAI, hip dysplasia, and femoral torsion abnormalities. But before we get into discussing approaches to evaluation and management, I'd like to first review the anatomy of the hip and the pathology associated with each of these conditions, and then how they can affect the health of the acetabular labrum and the femoral acetabular cartilage. So could you just start by reviewing for us the normal anatomy of the hip and then defining for what the pathophysiology of the various types of femoral acetabular impingement are and how that negatively affects the joint?
Dr. Matthew Kraeutler:
Sure. So when we talk about the hip joint, we're referring to the articulation between the femoral head and the acetabulum. And when we talk about FAI, FAI can occur on both the femoral side and or the acetabular side. So on the femoral side, if there's insufficient offset between the femoral head and the femoral neck, that refers to cam type FAI. And on the other side, if there's acetabular over coverage of the femoral head, that refers to pincer type FAI. It can also have, of course, both types of FAI concomitantly, which would be known as mixed type FAI. And both of these types of FAI negatively affect the labrum and the femoral acetabular cartilage. So we know from a recent study that we published a few years ago that in patients with cam type FAI, this results in a break in the chondrolabral junction. Whereas patients with primarily pincer type FAI have a sort of universal damage to the labrum as the labrum gets crushed between the sockets and the femoral head or head-neck junction.
Dr. Chris Tucker:
So knowing that that's an abnormality, could you now review for us a related but different entity called hip dysplasia? How does that alter normal hip mechanics and then negatively affect the joint?
Dr. Matthew Kraeutler:
So hip dysplasia refers to insufficient acetabular coverage of the femoral head, and this could be insufficient coverage either laterally, anteriorly or even posteriorly. The issue with hip dysplasia is really that it creates instability in the hip joint, and so patients with hip joint instability, the femoral head wants to subluxate out of the socket, and when it does so it can create sheer forces between the femoral head and the socket, and that can result in chondral damage or damage to the labrum as well.
Dr. Chris Tucker:
Yeah. And I think as we'll get into in a moment, one of the aspects of hip dysplasia that the labrum can play a larger role in hip stability than the labrum does in a normal hip joint, and you can have labral hyperplasia, and so that can affect the treatment algorithm and evaluation of those patients, so a really important topic for us to discuss. So lastly, you also explained the concept of femoral torsion. Can you talk about how abnormal femoral version can lead to injury to the hip joint?
Dr. Matthew Kraeutler:
Sure. So femoral torsion is probably the most overlooked to these three primary factors of hip joint preservation. Femoral torsion refers to the angle at which the femoral head sits in the acetabulum in reference to the posterior condyles of the distal femur. So a normal or an average femoral torsion is about 20 degrees of anti torsion. So the femoral head sits approximately 20 degrees facing forward. In patients with excessive femoral anti torsion, so say for example, 40 degrees, this creates instability in the hip joint because as the femoral head points more and more forward, that femoral head wants to come out of the joint anteriorly. In contrast, in a patient with femoral retrotorsion, although that actually makes the joint more stable, it causes two issues. First, it restricts a patient's hip internal rotation, and also it creates a higher likelihood for hip impingement because the patient has less internal rotation and they'll impinge more quickly than a patient within normal femoral torsion.
Dr. Chris Tucker:
All right. Great. I think that's a nice high-level summary of each of those three entities that you outlined in your infographic. So now that we have a clear understanding of what the normal hip mechanics are and the various factors that can lead to hip joint pathology, tell us your approach to the patient who comes in with non-arthritic hip pain. And how are you evaluating them physically and radiographically?
Dr. Matthew Kraeutler:
Well, sure. So whenever I see a hip preservation candidate, I want to evaluate them for all three of these primary factors for hip joint preservation because if there's an abnormality in any of these three and the patient has failed non-surgical treatment, then I want to make sure to fix that issue, whether it's one, two, or all three of the primary factors. So of course it all starts with a history and physical examination, but when we talk about imaging, I really think that plain X-rays, the most important, they give us the most information in terms of X-rays, CT, or MRI. When I get x-rays, I get an AP Pelvis X-ray in 45 degree Dunn views of both hips, and it's really important that that AP Pelvis X-ray is a perfect AP Pelvis X-ray. What I mean by that is it's not rotated one way or the other.
The coccyx is perfectly lined up with the pubic symphysis, and that allows us to accurately assess the acetabular coverage of the femoral heads, the balance between the anterior and posterior walls of the acetabulum, and really lets us accurately assess these patients. In addition to that, in patients who I think are going to move towards surgical treatment, I will also get MRI and CT. CT allows us to accurately measure femoral torsion, which of course is one of our three primary factors, and we want to have an accurate assessment of that. But I also get three day reconstruction of these CT scans, and that gives us a three day view of these patients' hips. You know, sometimes it's difficult to assess just based on plain X-rays, for example, how much anterior coverage there is of the anterior wall. And so having a three day view sometimes can be helpful to give us an overall picture of how stable that hip joint is or where the cam lesion is. And then MRI allows us to assess the status of the femoral acetabular cartilage as well as the status of the labrum.
Dr. Chris Tucker:
Yeah. I think it's a wonderful summary. I think important note, as you said, X-rays really is the starting point, and I think a lot of us who've done hip preservation surgery for a while do get those referrals where they see their primary care provider and they come with just an MRI. They don't quite understand why they need X-rays. I think that's part of the education process, and I think just having a command of those, you know, a commanding knowledge of those three conditions succinctly explaining to the patient, just like you have, I think really kind of lets them know the rationale for doing some extra studies and then what information you're going to gather from that.
Because I think for most people walking off the street, who may or may not have read about their condition before, they may not understand why they need, what seems to be a fairly intensive workup, but in reality, in my opinion, it's kind of just the baseline necessity to evaluate them thoroughly, like you said, to make sure we evaluate for all three of these conditions and don't treat one or two of them, and that's where we start seeing the rates of revisions for failures.
Dr. Matthew Kraeutler:
Yeah. Absolutely. This is definitely a thorough workup, but again, it's to make sure that we don't miss any of these important factors because if any of them is missed and there is an abnormality, that patient might not do well, and we don't want that to happen.
Dr. Chris Tucker:
So once you have a patient who's found to have FAI, talk us through the surgical approach to correcting this pathology and what are some reasonable expectations for the patient undergoing a hip arthroscopy for FAI?
Dr. Matthew Kraeutler:
Sure. Well, FAI is certainly the most common of these three factors that we see. And in a patient with isolated FAI, this can be treated with hip arthroscopy. We are going to perform femuroplasty for CAM lesions, acetabuloplasty when necessary for, pincer lesions, and of course, we are going to treat the labral pathology. Historically, labral pathology was treated with simple debridement. We know now that these patients will typically not do well with isolated debridement, and so our treatment nowadays is most often with labral repair. But in severe cases of labral pathology and particularly in patients undergoing revision hip arthroscopy, these patients sometimes necessitate the labral reconstruction.
Dr. Chris Tucker:
Yeah. We've had multiple podcast episodes discussing just those very things you've talked about, and there's a lot of nuances that go into the decision-making process, both preoperatively with factors like MRI measuring labral widths and heights, degrees of tears, but also intraoperatively, assessing stability of the labrum, the seal itself dynamically being assessed. So I think you are very nicely summarizing a fairly complicated thought process and a very technical procedure with a quite steep learning curve, but very nice discussion of the FAI. So moving on to acetabular dysplasia, could you speak to the surgical correction of that condition and just what is a patient expecting in terms of treatment and recovery?
Dr. Matthew Kraeutler:
Sure. So acetabular dysplasia is treated surgically with something known as a periacetabular osteotomy, or a PAO. This is a much more invasive surgery and simple hip arthroscopy. Patients should expect to be in a lot of pain, especially for that first week or two, and the rehab is much longer overall compared to isolated hip arthroscopy. But once patients have healed and once they've gone through the rehab process, these patients are very happy. They feel much better, and they can return to all activities without restrictions as opposed to, say for example, total hip arthroplasty where patients who have a hip replacement really should not be, for example, running marathons or skiing black diamonds. But if you have a PAO and you can preserve the native hip joint. Once that PAO is fully healed, there's really no restrictions.
Now, I should mention, when we are performing a PAO, we're not only trying to provide necessary lateral coverage of the acetabulum over the femoral head. It's also really important when performing this procedure to pay attention to the balance between the anterior and the posterior walls as well. If you give the patient too much anterior coverage, this is going to restrict their internal rotation postoperatively, and it may be enough where the patient's not happy because you sort of limited what they can do in their activities. Likewise, what we say, open them up too much, meaning there's insufficient anterior coverage, while they're still going to be unstable. So it's really important to pay attention to not only the lateral coverage, but also the balance of anterior and posterior coverage as well when performing a PAO.
Dr. Chris Tucker:
Yeah. I think that's a great point to make. And also I would add that there are cases where these two conditions can occur simultaneously. You can have dysplasia with intraarticular pathology, and so often these will be combo cases where cases a single hip preservation surgeon or two or a pair, you know, a team of surgeons could perform a concomitant PAO and hip arthroscopy to address labral pathology, intraarticular cartilage pathology, as well as realignment of the acetabulum.
Dr. Matthew Kraeutler:
Absolutely. This brings us back to the whole concept of this infographic, which is we need to assess for all three of these primary factors, and if there's an abnormality in two or three of them, all of the abnormalities should be treated if that patient has failed on non-surgical treatment.
Dr. Chris Tucker:
All right. So lastly, can you talk about probably the least commonly discussed factor, the femoral torsion. Talk to us about surgical correction options for that and maybe even touch on when it might be indicated and what are some expectations after that procedure?
Dr. Matthew Kraeutler:
Sure. So the surgical treatment for abnormal femoral torsion is with something called a derotational femoral osteotomy, or a DFO. This can be done either with a plate and screws or with an intramedullary nail. I prefer an intramedullary nail. It allows the patient to weight bear immediately postoperatively. There's less muscle stripping during the procedure and it's less invasive overall, I think. Now the question of when is it indicated is a tricky question because this is not a simple black and white answer. Now, I will say that if a patient has femoral anti torsion of say 40 degrees or more, I'm likely going to recommend a DFO in that patient. And on the other side, if a patient has femoral retrotorsion of negative five degrees or less, I'm likely going to recommend a DFO for that patient. But then in between, this is where it gets tricky. Say you have a patient with hip dysplasia and you're going to do a PAO on that patient, but upon your initial assessment, that patient only has internal rotation of five degrees.
If you if you do a PAO and you give that patient more acetabular coverage, that's going to reduce their internal rotation even more. And so in that case, I would also do a DFO to give that patient more anti torsion and maintain a physiologic internal rotation range of motion post-operatively. Okay? So this is when multiple of these factors come together, and we really need to think about how the interplay of these different factors plays a role in our treatment recommendations for these patients. Now, in terms of expectations from this procedure, I would say this is the longest rehab of all three of these procedures because when you perform a derotational femoral osteotomy, all of the muscles in the proximal and the distal femur sort of need to learn their new alignment post-operatively, and that takes a long time. It seems these patients take the longest time to come off their crutches. The overall rehab is just the longest, but again, once these patients have healed, they really do well and they can return to all activities.
Dr. Chris Tucker:
Yeah. That's a great summary of that. I think your infographic does a really nice job of outlining the major factors involved in hip joint preservation, which as we all know is a really exciting and expanding field where it seems like year to year the more questions we answer, we really only generate more questions that we don't know the answers to, and I think that's the impetus for the development of the field. You talked about the primary surgical approaches to correcting each of these three factors. Did you have any other closing remarks before we close out our podcast?
Dr. Matthew Kraeutler:
Well, Dr. Tucker, I just wanted to emphasize the importance of assessing for all three of these primary factors when you're evaluating a hip preservation candidate. If you're a surgeon who's trained in hip arthroscopy, but you have not been trained in the osteotomy procedures that we've discussed, I think it's really important to work closely with a colleague or with another surgeon in a neighboring practice who has been trained and does perform these osteotomy procedures. And whenever you're evaluating a patient who you think might need a PAO or a DFO, you have your colleague do an independent assessment of this patient and together come up with a final surgical plan based on both of your expertise so that you can come up with an optimal treatment for each of these patients.
Dr. Chris Tucker:
Yeah. I think that's wonderful thoughts and tips for putting the patient first and really coming up with a comprehensive treatment plan. Matt, congrats again on your work, and thanks again for taking the time to share your thoughts with us tonight.
Dr. Matthew Kraeutler:
Well, thank you for having me, Dr. Tucker. I really enjoyed our discussion on this very important topic.
Dr. Chris Tucker:
Dr. Kraeutler's infographic titled The Principles of Hip Joint Preservation is currently available in the July, 2024, issue of The Arthroscopy Journal, which is available online at www.ArthroscopyJournal.org. This concludes this edition of The Arthroscopy Journal Podcast. The views expressed in this podcast do not necessarily represent the views of The Arthroscopy Association or The Arthroscopy Journal. Thank you for listening. Please join us again next time.
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