Subtalar Arthrodesis for Post-Traumatic Subtalar Arthritis
My name is Chris DiGiovanni, and I am the chief of the Foot and Ankle Service at Mass General Hospital, and I'm one of the vice chairmen at Harvard Medical School in the Department of Orthopedics. So my specialty is foot and ankle, and the patient we're going to take care of today, I've been taking care of for almost 15 years. He's a gentleman in his mid-forties and had a bad fall many years ago in which he sustained a very severe fracture of his heel bone, his calcaneus, so we put it back together back then. It was in many pieces, and over the years, eventually took his hardware out, but he healed everything well. And since he damaged this bone and joint, he developed significant arthritis, so he’s got post-traumatic arthritis. And today we're taking him to surgery to fuse his joint because he is no longer amenable to conservative management. We've exhausted all different means of trying to - to palliate his symptoms and he can't tolerate this anymore, so what you're going to see in the video today is we’re going to set him up in the operating room in a supine position, and we are going to then prep and drape his right leg. He's already been given some numbing medicine. There’s a - what we call a popliteal blockade to numb him up after surgery so he’s comfortable. And we’ll give him some antibiotics, and then we will under tourniquet control, make an incision that you'll see is sort of the initial step on the outside of his hind foot, so the subtalar joint is the - and the calcaneus are two anatomic areas below the ankle, basically the heel. He will, I think, appreciate what we're going to do today for him if he heals it properly because it's called a fusion, and that means we're going to eradicate his badly arthritic joint where all the symptoms are coming from. And hopefully, his cells will - will bridge that with bone so there won't be a painful joint there anymore. So, step one for us will be an exposure of the joint through a small, maybe 1-inch incision called an Ollier approach. We're going to make sure we stay away from all the arteries and all the nerves and the tendons that course very nearby. Once we get into the joint, step two will be to clean out all the arthritis in the joint with curettes and osteotomes and rongeurs. And once we scrape out all the arthritis, our goal is to get it down to completely raw, bleeding bone, so that we can maximize the healing response. So step three will then be to drill up the surface, what we call the subchondral plate, and we’ll do that with some drill bits. Sometimes we use an osteotome or a burr, but today, I think, we'll probably use drill bits. Then, once we've got all the surfaces rawly exposed and hopefully maximize his chances of healing it, step four will be to go and takes some bone graft to help him heal. So, we can take bone graft from all kinds of places: the hip, the knee, the leg, the ankle, the foot even. But today, we'll probably take it from his tibia, which is below his knee, because we need a fair amount of graft because of all the damage he did. So, I'm going to guess we'll take between 5 and 10 cc of bone graft from his tibia with a special device that is a bone graft harvester. And then we'll plug that area, close it up, and then step the five will be to put that graft into his subtalar joint that we want to heal and prepare it for hardware. And then the last step will be to fix the joint - stabilize it with a couple screws. You can use staples or plates - wires. Today, I think, his problem is amenable to screws, so we'll put a couple screws in, which is pretty traditional. And then finally, we will simply close his wounds in layered fashion as soon as we're happy with what things look like on his x-rays. So we'll check his x-rays with a fluoroscan just to make sure we're happy with the hardware and the position of his foot. And once we are, we’ll close him up. And then we'll put him in a splint, then anesthesia will wake him up. We’ll put his tourniquet down and we’ll bring him to recovery. The whole process probably takes about an hour, maybe an hour and 15 minutes, give or take. And that's pretty standard I think, but this - this problem will take three months to heal, minimum. And a year to be at his best. So it's a long healing process even though - you know, as operations go, this procedure works pretty well. It's a good symptom reliever, pain reliever, and it makes people a lot more functional in life.
So this is a fairly young gentleman, who about 14 years ago fell ten feet out of a window and shattered his heel, his calcaneus. (unintelligible). And we fixed his heel bone, his calcaneus, back then, with plates and screws through this big, long incision. Traditional flap that we lift up to piece all the pieces back together like a puzzle. We had plates and screws and everything, and he eventually healed that well. And then we later brought him back to the OR and took all this hardware back out. So he's gotten a lot out of this. He's gotten 14 years out of it, but over the course of time, because he damaged his heel bone and his subtalar joint, he's developed progressive arthritis. So now we're going to convert his subtalar joint to a fusion. So we're going to scrape out the arthritis and probably put a little bone graft in and put some new hardware in to try to get him to heal that joint because it's such a damaged joint it's become very arthritic over a decade and a half. And so that's what you're going to see us do today. We could use this big incision, but I don't want to because it's a much more extensile approach, and it's a lot more surgery, and I don't think we need to do it, so we're going to do it through a much more limited exposure and try to accomplish the same task.
So we're going to start with our exposure, and - we're going to be very careful because there are extensors and nerves here, and there's a small sensory nerve in the peroneal tendons and the sural nerve here, so the apex of this incision is defined by the - by that anatomy, so that's where we're going to start. Starting. This is called an Ollier approach, or a sinus tarsi approach. It’s a good utility approach. It's not an extensile approach, but the nice part about it is that it heals well because it's in something called Langer's lines, which are like the skin lines. Two sharp Senns, please. Thank you. Yeah, I think you can buzz that. So what we're doing now is we're getting down through the subcutaneous tissues. We’re looking out for sensory nerves. We are cauterizing all the crossing vessels, and getting into this - what's called the sinus tarsi. I'll take a self-retainer, please. Hold on a second. So - sharp, please. So this is the base of the sinus right here that you can actually see quite nicely. And it's all the ligaments over the top of the subtalar joint. There are several of them.
Probably take a Bovie. And I would basically go in like this, okay? Yep. Very superficially and just be careful as you go inferiorly because you're going to have your peroneals nearby, and that's probably them right there. Yep, exactly. So he's staying above his peroneal tendons, which is very important. Once he knows where those are, this becomes a much easier procedure. And he's basically going into the subtalar joint. And now we're not quite there yet, going through a whole bunch of scar, but we're going to get there pretty soon. Okay, now come on out.
There you go. So you can see that this joint just barely moves. You can see it right here. Can I have a Freer elevator? There's the joint right here. Right there. There's not much left of it because it's quite arthritic, but you can see the movement. I'll take a right angle Hohmann, please. And then what we’re going to do is we’re going to sneak around this. It slides right around, just like that. And then, you can really start to see the joint. So he's going to - I'm just going to free this up a little bit. Right in here. There we go. There's the joint, or what's left of it. And then, what we're going to do is I'm going to switch places with Dr. Moon, and he's going to put a very small curette in here and - take down this joint.
So… Just - so anatomy wise, this is the talus. This is the calcaneus. He's going to be right between them in this joint, which goes in this plane, and he's going to sweep back and forth to take out the - the arthritic cartilage that remains, just like that. And… Thank you. Do you have a large neural tip? One of the - the 18, I guess. Stay in the plane of your joint. Keep going side to side. That’s it. Find your plane. Yep. The key with taking this joint down is not making a false track. You don't want to dig a hole. You want to stay in the joint, and it's - easy to dig a hole if you're not careful and paying attention. So the joint is almost like the joint of - the basilar thumb joint. It's sort of like tri-planar. It’s what we call a saddle joint. It goes up and over, but it also contours the other way too. It's not just a straight, flat joint. It's got several planes. And you have to know where you are and you have to know your anatomy. Pituitary, please. So you don't end up somewhere you don't want to be. So you can see, even though this joint's arthritic, you still do have a little cartilage left in it, which is typically the case. Just because a joint is arthritic doesn't mean there's no cartilage left. It just means that there's a lot less cartilage left and - and what's left isn't normal. So it's like - it's like being on the surface of the moon where you have little craters, you know, peaks and valleys - that's what arthritic joints look like. There are areas where they're, you know, in pretty good shape, and areas where they’re in horrible shape. But the problem is that the parts that are in horrible shape are the ones that make the joint painful. So even though part of the joint might be okay, the part that's not okay is what the patient has problems with. And we don't have a good way yet in life to put all the cartilage back. We're working on that. A lot of labs are working on how to put cartilage back, but we don't have that technology yet to any significant level. The other complexity for this joint is that you can't replace this joint. This joint is not - be careful with your structures down here. So unlike an ankle joint or a knee or a hip or a shoulder, you can't just replace this joint. This joint is not replaceable yet, we don't have the technology to do that. We've tried. I've actually designed a subtalar joint replacement years ago, but it did not work well. And others have tried, and it hasn't worked well for them either. So, this joint is biomechanically complex, and it's also - it's subject to tremendous forces. You can imagine, the whole body has to - has to put weight on this little joint, so it's asking a lot of a tiny little area, which is why joint replacement of this does not do very well. So we don't have the luxury of just taking an arthritic subtalar joint, after a bad heel injury like this gentleman had, and just putting in a new joint, so we have to fuse it. It's the only option we have that works very well. And it's a very good operation. It limits the motion because the - the joint no longer moves, but it's a very effective pain reliever. So as long as the patient heals this, it usually will last them the rest of their - it'll last the patient the rest of his or her life. And what usually brings them to the operating room is not stiffness. Even though they don't like to be stiff, what brings them to the operating room is pain. So it's the pain that you want to relieve. Now he's getting all the way to the side of the joint. You want to make sure you get the whole - all the residual cartilage out, any arthritic areas, you want to have basically two raw bony surfaces. That's the goal here because that will maximize the chance of this healing - fusing. No. So this joint is a very big joint too, so it's not only anatomically complicated - it's also fairly large, so just when you thought you'd gotten it all, usually you haven't. And it gets way in the back here, so you have to take the time with this joint because it'll fool you. Suction, please. So here are the peroneal tendons, right here. The sural nerve is probably right in here. And, we're going to get - reflect those out of the way, so just so you guys can see well in here. There's the joint, right there. You can see - see the space? And… Yep. Freer, please. So to show you what we're working on here, this is the joint, right here. Right in there. Now, you can see how far back it goes. You just put this back there, it's pretty deep, and we're not even all the way to the back, so - but we're close. This is a great lamina spreader - best one they make. Don't leave home without it. It's - you can't do foot and ankle surgery without this instrument. So we put this between the lateral process of the talus, which is right here, and the anterior process of the calcaneus, which is - right here. So, it goes between here and here. And we're going to try to open this joint up a little bit. And that opens it up somewhat. And - I'm going to let him come back in here. So when arthritic joints typically get tight because they get stiff, they scar. So, sometimes you have to use little lamina spreaders just to first get in there. So, self-retainer back, please. Now you can see the joint even better. Okay? I'm going to switch places and let Dr. Moon go at it. So one of the keys of surgery is being efficient, so once you have an exposure, you want to take advantage of it because you don't want to pull too hard on the skin or the soft tissues, so once you give somebody exposure, they need to quickly do their job - and that way you're not irritating the soft tissues of the skin too much, which is important. Now we're going to irrigate this joint up a little bit, just to flush everything out of here. Sometimes as you're working, all the stuff gets caught up in there, so he's going to put that in there and just flush it all out. More? Sure, one more. It also irrigates the tissue so the tissue doesn't desiccate, which you don't want to have happen, right? The only common denominator to all living things is water. Thank you. Now can I see my larger lamina spreader, please? Now maybe we can get the larger one in there.
How's that? Once we're done with this, he's going to take a 2.5-mm drill bit. Okay. From my set with a guide. You don't have to give me the same guide - give me a guide that's pretty long, not necessarily the guide that fits the 2.5 drill bit, so it protects the soft tissues. And then we're going to drill this up. So I think that Dr. Moon pretty much got this joint. It's looking pretty good here. And now what we're going to do is we're going to prepare this for fusion. Okay, now, I'm going to switch places with him, and he's going to drill this up.
He's going to carefully protect this tissue down here with his drill. That's what the drill guide is for. I call it a soft tissue protection sleeve. And he's going to drill multiple holes across the joint to perforate the subchondral bone, the subchondral plate. And what this does is it improves the blood flow to the area to maximize the chance of this fusing. It brings blood to the area. So it just makes a whole bunch of little holes all across the joint. So if you look in there, you can see all the little pieces of bone graft, and that's the goal here - is to perforate those holes. Now we're going to try the other side of the joint. You don't have to use a drill bit this big. Sometimes you can use a smaller one. This is a 3.2 drill bit. Sometimes I'll use a 2.0 or a 2.5. I basically will base the size of my drill bit on the size of the hole. You want to be careful when you're going this direction because the neurovascular bundle is over here. So you don't want to plunge because that's where the arteries and nerves are. So you want to be very cautious over here. We really mucked this up, and - it looks good, but now what we're going to do is we're going to take a little bone graft to fill that.
So, we're underneath the knee joint, this is the kneecap, patellar tendon. My thumb is right on the knee joint. This is called Gerdy's tubercle. This is the insertion, the tibial tubercle. Gerdy's tubercle is right here. We're going to go right over this to take a bone graft from there. The fibular head is over here, so I cheat a little bit anteriorly and below the knee joint because you don't want to be in the knee joint. I'll take two sharp Senns, please - probably one of the bigger ones. What's that? Yeah, medium or large. Yeah, now put your finger right in there. Probably going to use this one, on power. So we're trying now to get right down to the periosteum, below the knee joint. So there's - the knee is right here. We're going to come down. There's the - where the tibia begins to flare out, and this is the Gerdy's tubercle, right here. So we're going to go pretty much right here. I'll go straight to bone. And again, I always check my knee. I think I'm fine. And then we're going to take a little bit of this. We're just going to free this up just a little bit, so we can get in here. There we go. Okay, that's pretty good. Yeah, my knee joint - again, I'll check that to make sure I'm okay.
And this is something we designed to take bone graft. So we're going to put this right here. And we're going to aim it away from the knee joint. Just like that. We run a few centimeters like that, and then we basically break it up. Then we turn it back on. And you can see, it takes a whole wedge of bone graft very quickly. Then you take this off. You don't even have to take your hands off, you put it right in here, and you go like that, and you got a graft. So we designed this. It's a neat little technique for a dowel. Takes two seconds. Okay, there you go.
We'll take some irrigation. So here's the hole. You see we're outside the knee joint completely. And that's our hole. We're going to take a little irrigation. And then we're going to pack this. Because we take a fair amount of graft, I like to pack this. So that there's no stress riser here. So we're just going to irrigate this. We could obviously take a lot more graft if we wanted to. You don't have to. So there's our hole. That's how deep our hole is. It's right inside. You can actually look right in there. And, it's just a neat little technique. So I usually put a little saline on here because it - it makes the bone stick together. So we pack this in, and we just back-fill it so it's no stress - doesn't become a stress riser. So basically we're filing this with allograft, which is cadaver bone. Cadaver bone is good bone. It's human bone, but it doesn't have cell - it doesn't have the cellular or proteinaceous contributors to healing, and his graft does, right? His graft is still alive so it's got cells, in it. It's got all the growth factor proteins and everything, so we're taking that and putting it where we need him to heal, and this just acts like a filler. This is a great place to get bone from. It's safe, it's quick, and you can get a lot of bone. I could get 3-4 times as much bone as I took out of here if I wanted to, but I don't think we need it, but if we did, I could get it out of this hole. So now he's just gently going to tamp that down. so that it's almost as if we weren't here. Yeah, maybe a little bit more, just a hair more there, and then I think you're good. So we took out about probably 8 cc of bone graft. We're putting in probably 8 to 10. So you took out his own, the autologous, and you're putting in some… we took out autologous because that has the protein and the cells and all the things that are good for healing, and we're putting in cadaver bone, which is just structural. There's no cellular, there's minimal - there's no cellular, and there's minimal proteinaceous support with this. It's all been treated, right? It's all treated bone, but we don't need this to heal necessarily, we just need this as a filler. We do need his subtalar joint to heal, so… You don't have to use bone graft. We've written some studies actually and published them recently with level one evidence showing that you can also use other types of things like - Augment, which is recombinant platelet-derived growth factor - PDGF - and trical - and beta - tricalcium phosphate, which works as well as - as autograft does. Now use your tamp. I would tamp that in before you… Right? Otherwise, you get it all on the soft tissues, which you don't want to do. There you go. 6 5's. All right, now hold that buddy. I'll take my Freer, please. So I don't like to get any bone in the soft tissue. Bone is not designed for the soft tissue. Bone is designed for bone. So, I'll try to clean all of that up. That looks pretty good. And then we're going to take that Gelfoam, please. Now this is Gelfoam. This is like a hemostatic agent, but it's a great filler. So I put this right over the top, and it form-fills to this defect. And it literally sits right over the top, just like that. It's a neat little trick. And then we'll close that with some Vicryl.
Thank you. Sure. Two Senns, please. Let's see if I can show you that better. Yep. So now he's closing the fascia, right over this. Pickup, please. One more right there, yep. See that? Yep, there, yep. Good. So, that's all closed up now, and we'll deal with the rest of that later. Now let's go back down to where the action is.
So while my fellow's doing that, I'm going to make a little incision here for him so that we can put the screws in. So this goes right to the base of the heel. Right to bone. There we go. That's where we're going to put our hardware. All right, so he rongeured up the bone graft, and now I'll take my Weity, please. And we're going to - I'm going to have them put all this in here now. Yep, so now he's going to put all that in. I'll take a Freer. And all this graft gets shoved in here. Pack it into this space. This space is going to get compressed by the hardware, but we're going to shove this graft in as a way to enhance the healing response. Can I see that - the rest of that morselized allograft as well? We'll use that too. You got it. Might as well use it. Yeah, exactly. Exactly. You want the cancellous. All right. So he's got lots of graft in there. All right.
So now what we do is we hold this up, and we basically - I just go in a hair, and then I'm looking at my joint. All right, so kind of like that maybe, 45 degrees. So I wrap this. This is just something I like to do because if the metal ever hits it, it automatically puts a hole in the drape. Unfortunately, this Coban is not long enough. Can I get you another one? I'll take one more Coban, please. The metal won't usually poke through that, but if it hits the plastic, it'll poke through almost immediately. So this is just an adaptation I like to do. called insurance. Okay. Okay, we're going to image, guys. All right, that looks about perfect. That is in the calcaneus. It's about to go across the subtalar joint. So now we're going to go across the joint. Now I go into there. There. Now I take a feel of my ankle to make sure my ankle feels good - it does. Now let's check it. Okay, now we're going to get a AP ankle. And that looks perfect too. So you can see that in the ankle - not going through anything. It's in a perfect spot, and now I'm going to have my fellow, Dr. Moon, put in the next one. And he's going to start about a centimeter away, which is why - some people like cannulated screws with guidewires. I just use screws - drill bits rather. So he's going to start a centimeter away, and then he's going to sort of stay parallel but angle a little bit further distally - yeah, no, a little less. Yeah, that looks pretty good, right there. Now he should feel it go in. Once it crosses the joint, now he's in the talus, right? So he can go a little further. If it felt good, go little further. If you're in talus - you in talus? Okay. All right, let's take a look. That's going to be perfect as well. I like - that's perfect. Okay? So now, same thing. He's right at the subtalar joint. Now he's going to advance into the talus. Yep, now he's in talus - goes about 2 cm, yep. I think you can go further. Now we're using the 654 - the regular from the large frag. Okay, let's check that. That's ideal placement. Now let's get a AP. Try that. That looks good too. Save that. Those are both very well placed. The talus is a medial structure, so you want these a little on the medial side. So I'm going to put the first one in, and he's going to put the second one in.
Thank you. These are nice pliers because they're easy to use. So basically, I grab this. I keep my eye on what I'm doing. I pull that right out. Then I run my depth gauge in. Like that. These are usually 75s. And this measures 76, so that's good. So we're going to take a 75, please. 75 mm.
Okay, and then what I do - again, you can use guidewires if you want, but I'm not a big guidewire fan. I think if you know the anatomy - go ahead - this is actually faster. So you jiggle it, find the hole, and then just turn it. Don't angle it - just turn it. Once you get to the skin, you got about a centimeter to go. So we'll go right there. And then we're going to stop, and then I'm going to let him do his.
He keeps an eye on what he's doing. Yep, he's got a big hole there. This should be slightly longer - probably like 85 to 90. Yeah, it's about an 80 I'm measuring right now. You're measuring 8-0? Yeah. Let me take a feel of that. That what you got? Yep. 8-0, huh? That's probably going to be okay. There's his angle. He just touches it. He doesn't aim it. He just turns it. He's only got one hole. The screw will find the hole. And he's going to go right to where mine is, and then we're going to check the x-ray. If the x-ray looks good, then we'll just send him home. All right, let's take a peek.
Looks good. I like it. Okay. Once you get underneath, you want to be careful not to over advance this. Once you feel resistance, you stop - like right about there. Otherwise, you'll drive it right through the calcaneus. It's a subtle feel. It's a feel you have to get used to, but there's some subtle resistance. And that's all you need. All right, let's take a peek. Yeah. Ready? That looks great. Let's print that. I like it. You can see how the - where we put all the bone, you see the joint's gone. Now let's get an AP ankle. That looks good too. All right. That's all she wrote. Okay, so you can see those two screws are nicely in the ankle.
We're going to close him up. I'll take some Gelfoam, please. And some irrigation. So first we irrigate this out. And then we're going to put some Gelfoam in here. So I take a piece of Gelfoam, which I really like to hold graft in place, and I'm just going to shove this in here to keep all my graft where I want it. And it just sort of keeps it all in place - nice, nice and clean. So we're going to close this in layers. He's going to grab a deep layer there of fascia - yep - and he's got it. Yep. Those are - that's his deep layer of fascia over the sinus. He doesn't want to grab too much. He's got a perfect amount, so he doesn't get into the peroneal tendons. I'll take a suture scissor, please. So this closes nicely and seals it up well, so you get a nice tight seal. This patient will take about three months to heal. Good. And he'll go home today. So, there's our closure. Can I have a 3-0 as well? One of the nice things about this exposure - when I was talking about Langer's lines before - is that, as you dorsiflex the foot and evert, it relaxes the skin, you see? So it makes for a nice - nice, non-tensioned closure. The heel is in a neutral position, which is about 5 to 7 degrees of valgus, and about 10 degrees of external rotation, roughly. So it's very important to keep the heel in a neutral position. Because you line up what's called your mechanical axis for weight-bearing. Now fortunately, we fixed his heel years ago - 14 years ago - when he broke it and then later took his hardware out so that made this better because he didn't present to us with a terrible malunion, which is what happens if you don't fix these. So then you've got to not only fuse the subtalar joint - you also have to revise the entire heel, and those can be even trickier. We just close this with a little running stitch. So I usually like to make sure these are not too tight. I like loose - loose stitches. All right, so, that's it. So we're going to splint him, and let him go home today, okay?
We just finished my patient's procedure, and I think the game plan was as anticipated for the most part. We ended up putting two screws in and about 10 cc - 8 to 10 cc - of autogenous bone graft, which is bone from him. And he's on his way to recovery. It was very uneventful. His joint was quite stiff, which is not unsurprising because when you have post-traumatic problems like his, things tend to scar in a fair amount, so we had to remove some scar to get in there, and his joint was also pretty arthritic, so I think this was a good choice for him. It was not a very functional joint, and I'm sure it was pretty painful, so - we've got high hopes. I'm anticipating that he will heal this in 3 or 4 months. So we're going to start him in a splint. We'll then put him in a cast probably for 4 to 6 weeks, and then we'll transition to a removable boot, and then hopefully by 3 or 4 months, if things go well, I'll have him in a sneaker and back to regular activities and hopefully some exercise, and - and I'll continue to follow him along. Subtalar fusion is a time-tested operation. There are a lot of joints in the body that we can replace with joints like knees and things like - hips, things like that. You cannot do that to the subtalar joint. It's a very important joint. It's one of the essential joints in the foot, and it is responsible for side-to-side motion like walking on cobblestones or beaches or uneven surfaces - unlike the ankle, which is up and down motion. So, it is part of a very important joint complex, so we don't like to fuse these joints. We'd rather replace them. It's just that we don't have replacements that work well. We've tried them over the last hundred years. They don't work well. They still don't work well, and I don't envision a time - at least in my lifetime - whereby we will have a successful joint replacement. So for now, fusion is the gold standard. It does work very well. It makes them - these patients a little stiffer, but they're also much more comfortable for standing and walking and doing things - routine activities. The indications for subtalar fusion are many. Patients can have congenital abnormalities. They're born with deformities. They can be born with what's called tarsal coalition, which is when two joints are - two bones are stuck together when they're not supposed to be. Patients can have bad injuries, like this gentleman, with fractures around the ankle or the foot for that matter and end up with debilitating problems and significant dysfunction. And the subtalar fusion is a nice way - if the joint's really damaged - to alleviate a lot of the symptoms that come from the damaged joint. We have done this operation for people with infection. We've done it in patients who have had prior surgery that did not work well to salvage the joint and mitigate their symptoms. We've done it to realign bones or foot deformity like excessively like flat feet or conversely, extremely high-arched feet. So this operation really bridges many different pathologies in the foot and ankle and is a very effective operation. Contraindications are not many. If a patient has an active infection or a significant soft tissue compromise, whereby we're worried that we will not be able to do the operation and have the patient effectively heal from it without problem, then we will not do the operation, or if they're - a patient is sometimes a very unhealthy host and wouldn't tolerate surgery in general, that's another contraindication to doing this, but by and large, there aren't very many contraindications for this in patients who really require it. The most important two things about this operation - three really - is one is getting in safely and getting out safely to make sure you don't do any iatrogenic damage to the patient. Secondly would be making sure that you maximize the chances of them fusing the bone. So we published multiple papers on how important it is to get a fusion and what it requires to get a fusion. And obviously, if it doesn't fuse, then you have to start all over again. So, you don't have full control over that as the surgeon, and the patient doesn't have full control over it as the patient, but it's a team effort, and we have to do a good job. The patient has to take good care of it, and of course their - their cells and growth factors that circulate naturally in their system have to do their job as well. Assuming those things can happen, it will usually be effective in between 80 and 100% of the time, so the non-union rate for this operation is about 10%. But those odds are still pretty good by orthopedic standards. There really is no alternative to this operation if you have a significant hind foot problem that involves this joint. There are different types of ways to do this with foam blocks, and realignment osteotomies, and things like that, but the act of fusing this joint in and of itself is really a gold standard for this - for this part of the foot anatomy. It's a very important part of the foot because you bear all your weight through it, so another important thing about this joint is getting the alignment correct. You must, you know, so - you want to do safely. You want to get them to heal, but you also want to correct their alignment or maintain good alignment if they start with good alignment. But to get them to heal in a bad position is no more better than having them not heal at all. So, all of these are things that we need to keep in mind over the course of the operation, so - there's a lot of art to this as much as there is a science to it. Sometimes we do this operation arthroscopically, so I think the last one I did, which was a month ago, we did arthroscopically, so we do tiny little peak-hole incisions, and we just go in and scrape it out with a little camera, and then you can do it that way too. Frequently we do. This patient was not amenable to that because he had bad trauma to his foot and was full of scar, so this would have taken a long, long time, and that's probably not the right choice as a technique to fuse him, so we did him through what's called an open approach with a standard incision and an open exposure. But these can be done arthroscopically. They work pretty well. The risks are low. The recovery is reasonably quick. It's just that you have to pick the proper patient for them. The only other thing that I do - and I don't think anything I do specifically is unique. There are a lot of tertiary foot and ankle specialists who do this operation in their - you know, in their office, but we often use bone graft. So I'm a believer in some type of graft. You can either use the patient's graft, you can use allograft, which is cadaver bone, or you can use something called Augment, which has recently been FDA-approved. Aside from what I have mentioned, there are no immediate, earth-shattering technologies on the horizon that I'm aware of for this particular joint. I think that it would be nice to develop a joint replacement for this joint, but we tried to do that already ourselves in our own labs, and it's just - this is a very, anatomically-complex joint, one of the more complex joints in the body, and it does so much work per unit area, right? It's a small joint, yet it bears all your weight, so the force per unit area, or the overall stress that goes through this area, is substantial, and so you have to be careful with it and respect it for what it is and what it does. So in the immediate future, I don't see any major changes in the - on the horizon though, I think that one of two things may evolve and that is either a - the ability to replace the joint with metal or plastic, or replacing the cartilage. So you take a gentleman like this, and instead of fusing his joint because he has bad cartilage, maybe there will be a way in the next 20, 30, 40 years where we can simply resurface his cartilage to give him new cartilage. Those are things that I would say will be on the horizon, hopefully. So I didn't use cannulated screws. A lot of people prefer them because you can put guidewires in and just follow the screw over the guide wires. I like - I feel like it's good for fellowship training to teach these guys how to really memorize their anatomy and learn it well, so I don't let them use cannulated screws usually. I let them use a drill bit, so you sort of have to think exactly about where you're going and get it right. But the advantage of that is that, once you get comfortable and familiar with that, it's actually faster more expeditious procedure. So we basically position the screws to go up through the heel bone, the calcaneus, and then right across the subtalar joint and up into the talus, which is the bone inside the ankle. And, you know, it can be tricky, but, you know, when - after you've done a thousand of them, you sort of get used to them, and - and you have to vary what you do a little bit with the anatomy, depending on what their anatomy is. His anatomy was not normal, so it made it a little trickier for us. But you have to make sure that your screws do not go into the ankle joint, for example, which is probably the biggest risk, or to exit the heel bone where you have all the arteries and nerves going into the foot. Those are the two danger zones that you have to be careful to avoid. In a place like this where we see patients from all over the world, we see lots of interesting and unusual pathology, and there are lots of things that are often unexpected that we're forced to deal with, but that's part of our job. For this particular patient, I've been following him for a decade and a half, so I did not have any surprises in the operating room today, but I wasn't expecting any either. We've treated hundreds and hundreds of patients with bad traumas like this who end up getting this joint fused in a similar fashion, so while at the same time we like challenges and we like interesting, unusual cases and complex things to do, it's also nice to have some relatively straightforward things as well - without surprises today, so it's nice to have a mixture.