Hello, thanks for this opportunity to present this topic. We are going to talk about hip micro instability, and we're going to focus on technique tips, but also review a little bit identification of these types of patients. The literature to support it is somewhat too large at this point, and for purposes of a lab work to present today, but especially in the last five years, there's been significantly more data to support repairs and placations, but we don't have enough time to go over that today. So factors contributing to hip stability, we have the bony anatomy, obviously dysplasia, we'll review a little bit what borderline and true are, as well as increased femoral antiversion being two bony factors that contribute to it. Global coverage is a topic that's also been used to describe the bony anatomy and its relative contribution. The capsule itself, including tissues that are deficient, such as in connective tissue disorders, the labrum study showing that increases the service area by about 20%, so deficiencies in the labrum, hypoplasticity or tearing, or debridements can contribute to instability. The ligamentum teres, particularly with complete tears, but also partial tears are associated as a secondary sign of instability. And then, of course, the muscles and tendons provide a dynamic stability. And looking at this, really should look at all the factors, look at each of them and how it can contribute to overall stability. So in terms of the hip capsule structure and function, the iliofemoral has been the ligament that's been implicated the most. Instability, it resists extension and internal rotation demonstrated here, kind of draped across the front of the joint. Mark Safran's demonstrated that this ligament is the ligament that's cut in an interportal capsulotomy between the anterolateral portal and a modified mid-anterior portal for standard labor repair. And its treatment and repair at the end of surgery is important to consider. These are just some anatomical cadaveric descriptions of it. This is an anterolateral view showing this iliofemoral ligament being directly in the front. So hip instability, how does it occur? Traumatic is very rare, as well as iatrogenic. Iatrogenic is really, I think, a factor of resecting too much capsule or not closing it. So those are both factors that need to be considered. The resection of capsular tissue, particularly when trying to repair the labrum or perform a rim trimming, is something that requires being meticulous in terms of the dissection and preserving the tissues throughout a standard hip scope case. Atraumatic is not that uncommon, as I mentioned earlier, and we'll go through some of these associations in a little more detail. And then FAI-related with posterior subluxation in the setting of femoracetabular impingement. In these cases, we treat the CAM, and it's not a common cause. So micro-instability, it is extra-physiologic hip motion. It is difficult to diagnose and quantify. There's no specific definitive hip criteria. There's a lot of things to consider in making the diagnosis. It can be secondary to these connective tissue disorders, Ehrlich-Danlos Marfan's Down syndrome, and it's increased in repetitive microtrauma, such as in dancers. We see it more commonly in young females and patients who have bilateral hip complaints. These patients typically will have more severe impairment and pain, and they're also more likely to have posterior or lateral pain complaints. This is a diagram from Mark Safran showing that it is a circular problem. As patients decrease activities relative to pain, the weakness can increase, and the circular nature of the problem can continue to progress. On physical exam, looking at the Baton's criteria as demonstrated here, with a score of five or more being positive, a high total arc of range of motion, skin elasticity, this elbow skin scratch test. I also just feel the patient's skin as I bring their hips through the provocative testing and their examination. That gives you an idea. A positive dial test, as demonstrated here, with significantly increased external rotation in the supine position. Drawer testing, both anterior and posterior testing. It's important to learn what's normal in order to understand what is abnormal, so testing for this on a fairly regular basis, even in normal patients, can help to make the diagnosis. Specifically with posterior subluxation, you can feel a pop when the hip is hyperflexed and in a fader-like position. And then these patients will tend to have external snapping more commonly. An assessment of instability based on x-rays, all the standard testing that can be done to assess for dysplasia is important. MRI, I find rarely to be useful, but it can be used, especially in the post-operative setting to look for a capsular tearing or incomplete healing of the capsule and also in ligamentum teres tears, although I think the assessment in partial tearing can be limited on MRI. X-ray assessment, borderline dysplasia has been considered to be at between 20 and 25, with true dysplasia being less than 20. Again, I think it's important to look at all the factors and x-rays are one of them. Here's an example of a patchless capsule here on the left side. So a knife is penetrating the capsule. This is the sharpest beaver blade that I think is available on the market, and it really isn't able to penetrate the tissue. It just pushes it away. So a highly elastic capsule. Here on the bottom is the opposite, where we get, looking here from the anterolateral border, the same knife is trying to cut through the tissue, and it's very robust and a lot of resistance to actually being able to just cut through this. So how are we managing the capsule? Essentially, capsular management has not really been referred to in many studies. In this 2017 review, most studies did not even comment on whether there was any capsular treatment and about 50% performed a complete repair. So I think this likely doesn't reflect our understanding nowadays. So capsulotomies are several different types. Capsulectomy, removal of the tissue, is not recommended. The two most common are the inner portal and the T-capsulotomy, with some evidence suggesting that T-capsulotomy does increase visualization of the head-neck junction. Improved visualization, I think, should therefore be also associated with increased closure or attention to treating the capsule at the end of the case. This is what a capsule enclosure can look like. So here the instrument is being passed. The first pass is through the proximal leaflet. And this is a, there are several different instruments available on the market in order to pass this. This is one of those that I've used for many years. Here I'm demonstrating a lag suture technique that Mark Philippon taught me about 15 years ago and allows for doubling over of the suture within the capsule, which I think is also an added benefit to gain capsular stability. Capsular plication, as defined here by our MASH study group, was a volumetric reduction achieved by larger bites in the capsules, potentially more sutures, and an inferior shifting of the sutures. That's demonstrated in this diagram by Ben Dome in all three of those parts. So the way that the suture is passed, the depth of the suture passage, is important. It basically results in the imbrication and inferior shift, increasing a screw home mechanism, and it increases the tightening with extension as the hip is brought into extension on the operating room table, assessing the capsule to make sure that it stays intact. Here's a video of this. In my experience with the plication, I'm usually passing about four sutures instead of the customary two sutures for a standard repair. And depending on the extent of the laxity of the tissue, the number of sutures can certainly be adjusted. Here we're looking from the modified mid-anterior portal and passing the sutures through the anterolateral portal. This is done using a non-absorbable suture with each of these passes. The capsular repair in my hands is typically done with a vicryl suture, which is absorbable. Another option, which I think is generally underutilized, is if in some situations, if there's no good proximal leaflet to use in terms of the repair of the tissue, passing anchors into the acetabulum and then into the distal leaflet, or doing a combination of this with standard capsular leaflet repairs is an option. I think, especially earlier in the learning curve, if there's a relative absence of tissue, I think this is something that should be considered. When is it indicated? We've talked about a number of these factors, but I'd also like to include intraoperative joint distraction. So if distractibility is easy at the time of joint entry, that's another factor. And the last thing is ease of capsular entry with the cannulas. So if it's easy to penetrate with the cannulas, specifically a four or five cannula, or passing the needle even through the capsule, if it passes through very easily, then it's additional signs of laxity. So what's the verdict in 2021? I would say it's preserving capsular tissue when treating the joint, maintaining tissue throughout the case so that you have something to repair at the end. And then most, if not all, capsulotomies extending greater than about two centimeters are worthy of repairing or application. Thanks very much for your attention. If you have any questions, please reach out to me here or via email. Thanks a lot.

hip microinstability

capsular management

connective tissue disorders

physical exams

partial tearing