decompression of Baker's cysts and a little bit on some of my outcomes so far. I have nothing that contradicts what I'm saying today or has any interference with it. So Baker's cysts or popliteal cysts are probably better described as a popliteal bursa. They're located posterior medially between the medial head of the gastroc and the semimembranosus tendon consistently. It's really the coalition of the two bursas in these areas that cause the Baker's cysts. The incidence of Baker's cysts is about anywhere from 5% to 58% of patients who have knee pain. In a cadaver study, it was shown to be about 30% of patients have Baker's cysts. So symptoms of Baker's cysts, as you all know, posterior medial mass plus minus pain, usually just below the joint line. Those that are greater than 5 centimeters in the studies have seemed to be the ones that are most symptomatic. Pediatric Baker's cysts usually leave them alone. They will go away. The symptoms also associated with them, if you get tibial nerve compression, numbness, vein compression can cause swelling. And popliteal artery compression is actually fairly rare. And as you've all seen is pseudothrombophlebitis from the rupture of a Baker's cyst, commonly mistaken for DVTs, easily distinguished on an ultrasound. So again, consistently this is between the semimembranosus and the medial head of the gastroc. Here's the location of the cyst. And the cool thing is when you go distally to the joint, the neurovascular bundle is over here. And so in distal Baker's cyst where most of them are, you're completely protected from the neurovascular bundle by the medial head of the gastroc. However, be cautious when you go more proximal because here's your Baker's cyst, and here is your artery and your vein and your nerve all sitting right next to the Baker's cyst. So if you're going in a Baker's cyst more proximal, just be aware you don't have the medial head of the gastroc there to protect you anymore. So non-operative treatment of Baker's cyst frequently performed, non-steroidal anti-inflammatory is always a mainstay. Cyst aspiration and an injection can be done. Studies previously have shown that aspirating the cyst is actually equal to aspirating the joint and injecting the joint. However, I think now with the onset of ultrasound guidance and the ability to kind of lyse some of the septations that are present in most of the cysts is probably going to make direct ultrasound aspiration and injection superior to the intra-articular aspiration and injection. So more to come on that. Operative treatment obviously, open or arthroscopic. Open treatment has been fought with multiple problems such as flexion contractures, fistulas, recurrence and nerve injury. So arthroscopic treatment, if you only address the arthroscopic problems within the knee and just expect the Baker's cyst to go away, it does sometimes. But if you have grade 3 or 4 outer bridge changes along with a Baker's cyst, things are much likely less to improve if you don't also address the Baker's cyst if it's symptomatic. The studies, they only address the intra-articular pathology. And 11 of 16 patients still had symptomatic cysts by only addressing the intra-articular pathology. And again, patients with grade 3 and 4 chondromalacia were much more likely to have persistent symptoms. The technique that I used was originally described by Takahashi, and he's the first one to really describe the posterior anatomy of the knee and the anatomy of the Baker's cyst. The real procedure to do this was further refined by Ahn and Sansone. And first one to really realize there's kind of a one-way valve or a cyst. He identified the one-way valve, took care of it through the scope, and also thought about using a second portal here when you want to do work inside the cyst. So he would view through one portal and then also work through the other portal, which I've modified a little bit and found a little bit easier because it gets really crowded back here on the post-remedial side if you're trying to do everything through the post-remedial side. MRI follow-up back from Ahn had in one- to three-year follow-up 31 patients, and all of them had resolution of their cysts, or the cysts were present at less than 1 centimeter. So how I do this, routinely scope the knee. I address all intra-articular pathology. When I make my portals I have them hug the patellar tendon because it's a lot easier to get back into the posterior aspect of the knee if you're close to the tendon. I move my scope from the anterolateral portal to the anteromedial portal. I localize what I call the trifurcation, which is between the medial femoral condyle, medial tibial plateau, and the PCL. And this is where your scope is going to go. I pass my arthroscopic sheath into this spot under direct visualization. And then my scope is now in the anterolateral portal looking into the post-remedial compartment. This is the view you're going to get. If you can't get back there, then switch to your anteromedial portal. Or I have used longitudinal transpatellar tendon portals if I need to get around osteophytes and it's another way to get back there. To localize the posterior medial portal, I call this the POTC, the posterior transverse synovial enfold, which is present in every Baker's, almost every Baker's cyst I have taken care of. So identify the POTC. It is consistently there overlying the medial aspect of the medial head of the gas rock. And so looking posteriorly, I will then pass, first need to localize your posterior medial portal, pass something, a blunt cannula into the posterior medial compartment. Make sure you're going bluntly, saphenous nerve is variable on this side when you're going posterior medially, so just a nick in the skin. And then this is taking down the POTC lesion with a basket and shavers, leaving a fairly significant hole into the Baker's cyst. So I switch my scope into the posterior medial portal to look into the Baker's cyst. This is all the fun stuff I have found in Baker's cyst. This is actually some debris from when I did the debridement. It fell into the cyst, loose bodies, all sorts of fun things back there. If you want to remove the cyst itself, or you need to get into the cyst, I have found the easiest way to do this is transcystic. So I'll look at my MRI ahead of time, see where my cyst is closest to the joint, and then where the cyst is closest to the skin, needle localize it from there, and then just take a transcystic portal through there to retrieve loose bodies or whatever else. So my surgical technique, can you guys make sure my volume is off? Because I sped this up and I'll sound like a chipmunk. So again, medial tibial plateau, trifurcation, pass into the posterior aspect of the knee. This is the medial femoral condyle, we're looking at a right knee. Medial femoral condyle here, POTC lesion. Like I said, they're almost all the time. So this is the exterior view, and I look really fast, but like I said, I sped this up. So I use my needle to look, get the backflow of water from it, small nick in the skin, blunt trocar, and cannula, and get the backflow of water. You know you're there. Slide my shaver in. I really like these metal cannulas that slide right onto the shavers. So shaver in, again, first the blunt cannula, shaver in, and then the shaver really helps you define this POTC. So I always go in first with the shaver, and as you kind of peel it off, this is the medial head of the gastroc. As you peel it off the medial head of the gastroc, it becomes much, much more apparent. And so again, I just use the shaver to define it, and then I take a biting basket. Again, medial head of the gastroc is right here, and the medial to the medial head of the gastroc will be the opening to the Baker's cyst. So you can see how all this little debris likes to fall down the Baker's cyst. So again, and then back in with the shaver, clean out all your debris, enlarge your hole here, which is gonna go into the Baker's cyst, again, medial head of the gastroc here, and just take down the capsule, take down the POTC lesion. And then this is kind of fun, because you squish on the Baker's cyst, and you see all this cool Baker's cyst fluid coming in through your hole that you've just created. I'll switch then and put my scope into the posterior medial portal, into the cyst itself, and this is the visualization you'll get when you go into the cyst. So this is a pretty typical cyst with some septations. And this is if I do a transcystic portal. I check on the EMR ahead of time, see where my cyst is closest to the skin. And then you can transilluminate also. And here's a little friend in here that I took out through my transcystic portal. All right. Let's advance that. It won't... Let's go down here. Let's get it to advance. Next. And next again. There we go. All right. And this happens to be a 24-year-old ACL. You say, you know, young people, why do I care? I would normally not do anything with this Baker's cyst in a 24-year-old. He's got a loose body in his Baker's cyst, so he's got a big chondroflake in there. So make sure you know how to get in there. So over the past 10 years, I've probably done, or I have done more than 200 popliteal cysts, either decompressions or excisions. Most of them are decompressions only. I have two patients that have come back to me with recurrent cysts after... Or actually, two of these patients had previously had open excisions, and then I went back and did them arthroscopically. Multiple times, I will find loose bodies in the cysts. Two of the 200 have come back to me with recurrences, so I can't tell you if they've gone somewhere else or had recurrences or... And two patients had DVTs out of the 200. So I said to my med students, okay, let's go look at these. And so these are my medical students that worked with me at Michigan State to kind of look at the patient-reported outcomes. So again, over the 200 patients over 10 years, they picked 37 from just a one-year series. The age here is the range 44 to 78. We looked at what the chondral injuries were in this patient, and you can see here the range of chondral injury. Three patients had had total knee replacements over the past four years. One patient had gone back to have another partial medial meniscectomy. I had only four patients with repeat MRIs. We're looking at getting these back and ultrasounding them now. But this is a very typical finding on these people. This is a pre-op evaluation on this patient. This is a post-op evaluation on this patient. So we looked at symptoms on these people in mostly questionnaire type of method. This was also a COVID study. And so we got what we could. And we're still ongoing and looking at these. But we just called and said, okay, what were your symptoms prior to surgery? Here are the patients that had pain and fullness in the back of their knee pre-surgery. Here's how they felt post-surgery. And these are all retrospective, so they're trying to recall how they felt before. Prior activity limitations, prior to surgery, this is only the portion that had none or some. And again, much improved with only a small number of patients going from significant here to significant here. So it definitely improved patient activity levels. We basically just asked, do you feel like your cysts came back? 68% of them said no, again without having the diagnostics on many of them, we just asked. And then Lysome scores, this is a post-op Lysome score. And you can see a significant number of patients in good and excellent. And then we decided to just sort out and add an extra question for knee pain, or posterior knee pain to see if that changed our results at all. And it really did not. So remember POTSI, posterior transverse synovial infill. This is a patient with a POTSI. I did a lot of looking in posterior knees to see if people had them who didn't have Baker's cysts. This is a patient without a POTSI. Remember where the cyst is. It's medial to the medial head of the gastroc. It lies between the medial head of the gastroc and the semimembranosus. And these are my criteria to decompress these popliteal cysts. If they're symptomatic, if they have grade 3 or 4 chondral changes and symptomatic, if they have a chance of recurrence in patients with recurrent effusions such as RA or CPPD, where they're going to continue to have recurrent effusions no matter what you do, I will consider decompressing the cysts. Cysts greater than 5 centimeters tend to be symptomatic in patients who have loose bodies within the cysts on the MRI. So I thank you for your attention.

Baker's cysts

fluid-filled sacs

back of the knee

symptoms

treatment options