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Contemporary Surgical Management of Posterior Cruc ...
Contemporary Surgical Management of Posterior Cruciate Ligament Injuries - Why, When, and How? (1/5)
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Video Transcription
Thanks again for joining us. It's an honor to be with you today. My disclosures can be found online, none of which are relevant to the content of this specific talk. I will just acknowledge that a lot of this has been gleaned from the experts, many of which are in the room, as well as these kind of key opinion leaders on this topic. It's been said that it's unlikely that a single physician will personally care for more than a few needless locations, but I'd submit to you they probably haven't been to Dustin Richter's practice because he seems on, I think, like once or twice every clinic. And I would certainly say the Southwest was good to me in that sense, too. When I was stationed down in El Paso, I felt like this was an epicenter for high-energy extremity trauma. And we know the incidence is listed as quite rare, but unfortunately, the true incidence is probably underreported, and it's likely due to spontaneous reduction and variable definition. These are the types of patients you can see. This is a patient of mine who's a horse jockey, falls off his horse, dislocates his knees, zips open his pants, and then just goes ahead and takes a selfie of this for confirmation purposes. You can see he's in these very loud Easter shorts here on the right, and you can see the evident sag, and so this is a pretty evident PCL injury. But they're not always as glaringly obvious. They're listed as low and high-energy, and so you certainly have to take all these very seriously as there's a high rate of concomitant injuries, and these are both involved in the axial skeleton as well as other joints within the body. The findings, again, they can be quite subtle. You want to look for this dimple sign, which can indicate that you've buttonholed through that medial complex, and you also want to be aware of the neurovascular anatomy and the various different subtypes by which they present. Again, neurovascular anatomy is key. The incidence of these can be up to 40% of knee dislocations, and there's a high rate of transection, particularly in the posterior knee dislocations. You want to be aware of the hard and soft signs, and ultimately, we often use the ABIs as a screening tool in the emergency room to assess it. If there's an ABI greater than .9, you can probably serially observe in the hospital with bed evaluations. If there's somebody that has an ABI less than .9, I think an arterial-based study, either CT angiography, arterial ultrasound, or MR angiogram can be very beneficial, and we'll dig into the studies of choice. When you have a non-flow-limiting intimal injury, it's rarely likely to progress to occlusion, but it can, so you want to pick those up early. Serial observation can be beneficial in those cases. If there is a complete occlusion or disruption, you should consult your vascular colleagues immediately. Surgical exploration would be indicated, external fixation, a vein graft, and then obviously a prophylactic four-compartment fasciotomy to account for the reperfusion injury. Again, neurologic injuries can also occur, and these are common with those lateral-sided peel-offs, those en masse avulsions, and it's commonly involved in the perineal nerve. This can be present in up to 42%. It's important to try to document whether these are partial or complete. You can see the complete palsies come back only in about 40% of patients recover against gravity, versus a partial palsy when present, about 90% of those can recur and age as a predictive factor for neurologic recovery. How is this managed? It's definitely managed in a multidisciplinary fashion. You want to incorporate your foot and ankle in your microsurgery slash hand colleagues. Serial EMG neuroconductive studies is beneficial. There's two schools of thought. The early intervention for neurolysis of the perineal nerve, just to remove any investing scar tissue, and perform an end-to-end repair. Late treatments can include seral nerve grafting, direct transfer of the tibial nerve, a motor branch, and then a posterior tibial tendon transfer through the anterosseous membrane. Posterior drawer testing, to pivot to the clinical testing, is kind of your workhorse for assessing the station of the knee, as well as the degree of AP laxity. I think it's important to use the thumbs test to assess where you sit. The normal knee should sit about 5 to 10 millimeters anterior to these condyles. So if your IPs are still flexed when you're performing that posterior load, that indicates at best it's a grade 1. If you're flush with the condyles, that's a grade 2. And then hyperextension of your IPJs would indicate a grade 3. So good rule of thumb, literally. Quadriceps active test is good. If they're in a flexed position, you want to have them push their foot down into the bed. And what you'll see is that translates the tibia forward, and that's with the activation of the extensor mechanism. That SAG sign, which we saw previously. And then I also like to check the dial test as well. Obviously these PCL injuries don't occur in a vacuum, so you want to assess for other concomitant injuries. The greater toe recurvotum test is helpful for me. This can be indicative of combined rotatory instability constellation. And I measure this in heel heights, or centimeters, especially versus the uninjured, hopefully contralateral side. Plastic imaging is a workhorse for evaluation, but you must be aware that up to 50% of these can have spontaneous reduction. And a high subset of these do not present in dislocated state. And they probably trickled through various different echelons of care. So you want to look for some of the subtle signs. Get orthogonal views. Look for any joint asymmetry. Look for avulsion of rim fractures, which can portend higher rates of instability. What we've seen consistently time and again with all the cruciate literature is that slope matters. As it relates to PCLs, a decreased tibial slope, or a flat slope, can lead to increased translation and increased stress, especially in a PCL deficient knee. This is just borne out in several of these studies, which I've listed for completeness sake. So alignment, both sagittal and coronal, does matter. When present in a chronic state, especially a varus knee, this can be addressed and possibly a candidate for a biplanar osteotomy. And Volker will address that in his talk. What about stress imaging? Obviously, we've talked a little bit about static imaging. But stress imaging, including the kneeling stress view, or using these proprietary instrumented tools can be very helpful for trying to tease out and lend objective data to an assessment of these tweener cases. You can see a partial injury can be present with a side-to-side difference of up to 7. If it's greater than 12, you should probably be looking at a PCL and a coroner. And that's certainly a good pearl that I've taken from the Vail group and others. You can see this is just a demonstration of what this looks like. It's very reproducible. You want to make sure you're getting those long tibial assessments so that you can have a better idea of the posterior cortical reference point. Additional imaging, again assessment of this side-to-side laxity with varus and valgus stress at 0 and 30 degrees. LaPrade's group has done an excellent job of lending us some numbers that we can take to the bank, both for the medial and lateral side to identify partial versus complete injury. And I would just mention standing hip to ankle alignment views would be very helpful. This is just what some of those look like. In terms of advanced imaging, it's ideal to obtain this post-reduction unless it's irreducible and you're trying to assess for what's the impeding structure. Magnetic resonance imaging can assess not only for ligamentous integrity but the high preponderance of articular and meniscal injury, whereas CTs are helpful, especially with 3D reconstructions when you do have a periarticular fracture post-reduction. And can also be a benefit to assess for nerve continuity and vascular status as shown here. An exam under anesthesia can be very, very valuable. You know, this is an excellent way and you should develop just a very rigorous process for assessing not only the injured but the uninjured knee. And this is a patient of mine that had a KD3 and you can see the positive dial test here. These are the injury patterns that you can see. Again, high preponderance of concomitant injuries. You can see this morel level A lesion right here in this individual. And you can see this is not only a limb-threatening injury but a life-threatening one as well. The skank classification, and my resident wasn't wearing shoe covers for that, so I think that's something he'll regret for the rest of his life. I don't think that made it to the next day. So the skank classification, we certainly borrowed this from New Mexico. And it's been excellent. We're continuing to try to innovate in this space to see how we can better communicate information, particularly with fracture and bony involvement. So it's important to know this. What about management? I'll just tease out some of these nuances and then the rest of our panelists will take it home. You know, my approach is just a brief period of immobilization, range of motion, and try to get it in this early window, especially when there's threatened soft tissue, distally based, post-traumatic coronary involvement, these avulsions where we can tack these down quite readily, any extruded menisci and extensor mechanism disruptions. A delayed definitive reconstruction can also be performed, but you want to be careful as you get towards that third week because that woody edema can really set in and it's really hard to tease out the native anatomy. I still like to do a bone-preserving, a single-bundle approach for the ACL and PCL. I'll use these all-inside graft constructs in order to reconstruct the central pivot and then an open RCRO technique in the audience and then marks with the medial side in general with a standard modification if posterior medial coronary is more involved. Order of fixation, this is something that I believe Dustin will dig into. Thank you and I look forward to your questions in the case panel. Thank you.
Video Summary
In this video, the speaker discusses knee dislocations, specifically focusing on posterior cruciate ligament (PCL) injuries. The speaker mentions that the true incidence of these injuries may be underreported due to spontaneous reduction and variable definitions. They highlight the importance of recognizing subtle signs such as the "dimple sign" and being aware of neurovascular anatomy. The speaker also discusses the management of these injuries, including the use of arterial-based studies, surgical exploration, external fixation, and neurolysis of the perineal nerve. They emphasize the importance of a multidisciplinary approach and various imaging techniques for evaluation. The speaker concludes by briefly mentioning their management approach and mentioning the Skaggs classification for bony involvement.
Asset Caption
Brian Waterman, MD
Keywords
knee dislocations
posterior cruciate ligament injuries
dimple sign
neurovascular anatomy
multidisciplinary approach
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