Subtalar Arthrodesis for Post-Traumatic Subtalar Arthritis
Table of Contents
Subtalar arthrodesis is currently the mainstay treatment option for the management of recalcitrant subtalar arthrosis. Arthrosis is a degenerative joint condition that results in a painful, functionally-impaired joint. In the subtalar joint, this typically follows trauma to the hindfoot resulting in talus or calcaneus fractures in particular. Although anatomic reduction of these injuries reduces the chance of later complications, arthrosis is reported even following anatomical repairs. The goal of the fusion in this circumstance is to remove a painful joint. A broad range of both congenital and acquired foot conditions include subtalar arthrodesis as part of their management strategy.
This video article details the methods and techniques involved in subtalar arthrodesis. After an Ollier approach was used to expose the subtalar joint, the subchondral plates were prepared by inserting an autogenous bone graft. Finally, compression was achieved by two lag screws. The process of obtaining an autogenous bone graft from the proximal tibia using a bone harvesting device is also illustrated, and opinions and expectations on the future direction of the management of this arthritic joint condition are discussed.
Subtalar arthrodesis is a well-tolerated treatment for remedying some of the most common symptoms that stem from advanced post-traumatic subtalar arthritis. The primary goals of this surgical procedure are to mitigate pain, restore alignment, and confer improved stability of the hindfoot by eliminating painful motion, arthritis, and deformity at the subtalar joint through fusion.
Painful arthritis and deformity are common sequelae after calcaneal fractures, the majority of which involve the subtalar joint. This bone supports all of one’s weight, helps maintain alignment and function of the structures around it, and comprises a significant portion of the subtalar joint above it which functions as the primary inverter and everter of the foot to facilitate accommodation on uneven surfaces. Disturbance of these relationships as a result of trauma to the bone and joint can therefore have profound consequences—making anatomic reduction and realignment critical during surgical fixation of calcaneal fractures for delaying the deterioration of the subtalar joint. Unfortunately, even in the best of circumstances many patients still go on to develop post-traumatic arthritis after calcaneal fracture, and unfortunately, there has yet to be a successful way to replace this joint once it has been damaged.
Conservative treatment options for post-traumatic subtalar arthritis include activity modification, orthoses, and corticosteroid injections. Minimally invasive procedures including arthroscopic debridement may provide relief, but are usually only temporizing. Arthrodesis—or fusion—has historically been the most reliable and definitive form of treatment once conservative measures are no longer adequate—and generally results in improved clinical outcomes if successful.
Subtalar fusion has the ability to not only eliminate the painful motion from the arthritic joint but also restore more normal anatomic alignment when necessary. When only fusion is indicated for the calcaneus and subtalar articulation then an in-situ arthrodesis can be performed with a 90% chance of success. When hindfoot realignment is also required, in order to improve altered mechanics or shoe-ability, additional, more complex procedures must be concomitantly performed to correct distorted anatomy, such as bone block grafting, osteotomy, tendon relocation or release, and other intervention. This video demonstrates the technique used for in-situ subtalar arthrodesis in a patient who developed subtalar arthritis 14 years after a calcaneus fracture ORIF.
The subtalar joint is a complex diarthrodial joint formed by the articulating surfaces of the anterior, middle, and posterior facets of the talus bone above and the calcaneus bone below. Since the majority of calcaneal fractures are intra-articular and result in articular surface disruption, attempts at surgical correction and fixation of these injuries as best possible are common. Intra-articular fracture of the calcaneus predisposes to subtalar joint degeneration (known as arthritis) via trauma-induced chondrocyte death and abnormal loading (contact pressures) that result from residual joint incongruency or malalignment.1 As such, anatomic reduction of the subtalar joint and restoration of hindfoot alignment as much as is feasible following injury are critical to maximizing patient outcome after calcaneal trauma. Although subtalar arthritis is known to be the final common pathway of most intra-articular calcaneal fractures, surgical reduction and fixation have been shown to maximize joint longevity and significantly slow the need for early fusion surgery. 2–5 Nonetheless, by virtue of the fact that many of these patients are often young at the time of injury and by definition damage a bone and joint complex that is forced to do more work and bear more load than most other parts of the body, many still end up facing the need for a second fusion procedure in their lifetime.
The primary function of the subtalar joint is to invert and evert the hindfoot and effectively transmit the load from ankle to foot. The subtalar joint, therefore, facilitates ambulation and shock absorption during gait and on uneven ground surfaces but also plays an important role in foot and ankle proprioception and propulsion during the gait cycle. As a result, advanced subtalar joint arthritis may be associated with significant limitation in performing both recreational and work-related activities. Subtalar joint arthrodesis alleviates pain and improves function by removing the injured articular surfaces, eliminating painful motion through the diseased joint, and restoring stable alignment. Patients usually benefit from deformity correction and restoration of stability to the hindfoot, with generally well-tolerated losses in subtalar motion.
The patient is a 45-year-old, otherwise, healthy male who developed post-traumatic arthritis of the subtalar joint 14 years following a work-related injury in which he sustained a comminuted, joint-depression type calcaneal fracture after a 10-foot fall from a ladder. He underwent acute open reduction and internal fixation (ORIF) of his calcaneus via a standard extensile lateral exposure following appropriate soft-tissue settling. He went on to routine fracture healing 12 weeks post-injury and eventually returned to work as a glazier 11 months after surgery. He later underwent implant removal and lateral calcaneal wall exostectomy for treatment of fibular impingement symptoms and hardware irritation approximately 8 months after his index procedure.
Seven years after the initial injury, the patient began to experience progressive hindfoot pain, primarily during weight-bearing or following activity. Imaging at this time revealed progressive degeneration of the subtalar joint, for which he was treated with orthoses, corticosteroid injections, and arthroscopic debridement. After exhausting both conservative and minimally invasive treatment measures at 14 years post-injury, he finally elected to undergo elective subtalar arthrodesis. At the time of this procedure, the patient’s medical and surgical histories were otherwise unremarkable. Plain radiographs of the hindfoot demonstrated complete healing of the calcaneal fracture and reasonable anatomic alignment, but end-stage degeneration of the subtalar joint.
Patients presenting with fractures of the calcaneus often exhibit moderate to severe swelling and ecchymosis about the hindfoot. Overt or subtle deformity may also be evident. Classically, this involves shortening and widening of the heel in conjunction with varus hindfoot alignment. Peroneal tendon instability secondary to rupture of the peroneal retinaculum may also occur in up to 30% of fractures.6, 7 Due to the high-energy nature of these injuries, injury to other anatomic sites is not uncommon. Injury to the lumbar spine, in particular, has been classically associated with calcaneal trauma. Those who present with arthritis and/or deformity symptoms of a more chronic nature typically present with complaints of pain during gait or on uneven surfaces, difficulty wearing shoewear, ankle or hindfoot impingement, difficulty with push-off, and/or chronic swelling.
Pre-op X-ray Image Post-op X-ray Images
Figure 1: Pre-op lateral ankle X-ray. Figure 2: Post-op lateral ankle X-ray. Figure 3: Post-op ankle X-ray.
As with most arthritic processes involving the musculoskeletal system, the natural history of post-traumatic arthritis of the subtalar joint involves progressive joint degeneration and worsening symptoms of pain and stiffness. Clinically, patients experience progressive start-up and activity-related pain, increased joint immobility, and loss of function. While symptoms may be mitigated by conservative measures and activity modification, fusion surgery has stood the test of time as the most reliable and definitive form of treatment for this joint once symptoms have failed conservative measures—to date, no effective, durable joint replacement has ever been discovered akin to that for other major joints developing arthritis such as the hip, knee, and shoulder.
Subtalar arthrodesis is currently the most predictable means of permanently alleviating much of the pain from an arthritic subtalar joint. This is achieved by removing the diseased joint and creating an environment whereby the patient’s cells can hopefully fuse talus and calcaneus together.
There are a number of considerations that must be taken into account by both patient and surgeon when choosing a surgical approach. Each has respective advantages and disadvantages. Options for approaching the subtalar joint in order to fuse it include using one of the following: 1) all or part of a pre-existent extensile lateral incision, 2) making new arthroscopy portals from posteriorly or anterolaterally, and 3) the sinus tarsi (so-called Ollier) approach. The use of a prior incision may be advantageous in cases of planned hardware removal or if a bone distraction arthrodesis is to be performed which requires a large volume of exposure for graft introduction/fixation. It may also be helpful in cases whereby the surgeon also plans to address the peroneal tendons, is considering lateral wall decompression for impingement symptoms, or must simultaneously manage a sural neuropathy—since this exposure is typically located directly laterally over these anatomic regions. The alternative use of minimally invasive posterior arthroscopic incisions, on the other hand, can be advantageous when the joint remains easily manipulated and overall reasonably well aligned. This approach carries less surgical risk of wound complications, nerve injury, or infection/healing issues given its minimally invasive nature, but that advantage must be counterbalanced by the more limited exposure offered by these portals—so it must be selected in the right patients for whom all goals are still achievable through this exposure. Although a more technically demanding approach, arthroscopic exposure also has the advantage of being introduced through native (not previously scarred) tissue. Finally, a sinus tarsi approach or Ollier incision can be considered when none of the more involved adjunct procedures mentioned above (lateral wall decompression, distraction/fusion, etc.) are necessary to be accomplished in addition to the fusion procedure itself. This smaller, open approach provides the surgeon the ease of a fresh exposure with the advantages of lower surgical morbidity by virtue of this being a smaller exposure than using the former “L” shaped lateral incision that was previously used for fixing the broken calcaneus. Furthermore, a sinus tarsi approach affords better direct access to the subtalar joint than any single limb of an old extensile approach as it is placed directly over the joint, and it allows easier mobilization of a very stiff, scarred post-injury and post-surgical joint than an arthroscopic approach when this becomes necessary.
In summary, the case presented is a 45-year-old male who underwent in-situ subtalar arthrodesis 14 years following surgical treatment for an intra-articular calcaneus fracture. Calcaneal trauma is one of several causes of subtalar arthritis that may ultimately benefit from subtalar arthrodesis. Subtalar arthritis may also occur secondary to talar fracture, subtalar dislocation, abnormal hindfoot alignment, or other disease states causing systemic arthropathy. Several studies have reviewed outcomes after calcaneus fracture management, and over 5 times the number of patients who sustain a calcaneal fracture will need to undergo subtalar fusion after initial conservative management as opposed to initial surgical realignment and fixation.3, 5, 7
The biomechanics of the hindfoot are complex. The normal anatomy of the subtalar joint allows for 30 degrees of inversion and 15 degrees of eversion. 8 The subtalar joint plays a critical role in transverse tarsal joint flexibility allowing for energy dissipation during heel strike. This is permitted by rapid eversion of the subtalar joint. In contrast, inversion of the subtalar joint locks the transverse tarsal joint to maximize power during toe-off. Prior biomechanical studies have found that talonavicular motion is reduced by 75% after subtalar arthrodesis by affecting this coupled locking and unlocking mechanism in the hindfoot.8
Surgical techniques for subtalar fusion are determined by surgical indication and anatomic considerations. In patients with preserved Bohler’s and talar declination angles, in-situ fusion is generally recommended. Prior studies have suggested improved outcomes in patients undergoing subtalar fusion after surgical treatment for a displaced intra-articular calcaneus fracture when compared to those managed non-operatively. Radnay et al retrospectively reviewed 69 patients with 75 fractures who underwent subtalar fusion for post-traumatic arthritis after calcaneal fracture. Improved Maryland Foot and American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scores were observed in those undergoing fusion after surgical fixation of their calcaneus fractures than those initially managed non-operatively. They concluded that initial open reduction and internal fixation lead to better outcomes by restoring calcaneal shape, alignment, and height, thus making in-situ fusion possible without necessitating extensive reconstructive adjuncts.2
Outcomes following in-situ subtalar fusion have, however, not been uniform, and these procedures are neither a guarantee of clinical improvement nor risk-free—and in no case do these patients end up with a “normal” foot post-treatment as if they had never sustained a calcaneal injury in the first place.10, 11, 12 Hollman and colleagues reported on 40 patients treated with subtalar arthrodesis for posttraumatic arthritis at a mean follow-up of 6.8 years. 9 The majority of patients reported less pain with a median Maryland Foot Score of 61. Quality of life remained significantly lower than reference populations, nonetheless, 90% of included patients indicated they would recommend the procedure to others suggesting high levels of satisfaction. 9 Hungerer and colleagues studied outcomes of primary and secondary (revision) subtalar arthrodesis in a large cohort of primarily worker’s compensation patients. Outcomes were relatively poor with a mean AOFAS hindfoot score of 47 and only 30% of patients returning to work following primary fusion.10 It should also be noted that reported fusion rates in primary subtalar arthrodesis vary considerably, with one study reporting a rate of pseudoarthrosis as high as 23.8%.11
Patients who have anterior or fibular impingement symptoms or significantly distorted anatomy may be indicated for subtalar arthrodesis with bone block distraction or osteotomy techniques. Rammelt and colleagues examined outcomes of distraction bone-block arthrodesis for calcaneal fracture malunions in 31 patients. Mean AOFAS hindfoot scores improved from 23.5 preoperatively to 73.2 at a mean follow-up of 33 months. Talocalcaneal height was corrected by nearly 62% and the talar declination angle by a mean of 38.5 degrees. They reported four complications including one dislocation of the bone block and one persistent infection.12
A number of techniques for in-situ subtalar fusion have also been described.13, 14 In the last fifteen years, the prone posterior arthroscopic technique has emerged as an attractive alternative to open fusion. In perhaps the most comprehensive report to date on the technique, Rungprai and colleagues retrospectively compared outcomes of this technique with a standard open fusion. They observed no difference in union rates, time to union or standard outcome measures. However, their results suggested that return to work time may be decreased with the arthroscopic technique.15
Various screw fixation constructs for achieving fusion have also been examined. DeCarbo and colleagues retrospectively reviewed 113 cases of subtalar fusion, divided between one and two screw fixation depending on surgeon preference. Fusion rates did not differ significantly between the two groups. Prior biomechanical studies, however, have favored two screw constructs.16 Chuckpaiwong and colleagues performed a cadaveric biomechanical analysis of four fusion constructs: a single talar neck screw, single talar dome screw, double parallel screws, and double diverging screws. Overall, higher compressive force, torsional stiffness, and resistance to rotation were observed with the double diverging screw constructs. 17
Finally, many options exist for bone grafting. While bone grafting is not critical for successful union, the use of bone graft has been associated with increased fusion rates. Common sites for autograft include the iliac crest, fibula, and proximal tibia, as used in our case. 13, 14 Autograft harvesting, however, is not benign and does confer additional surgical risks and the potential for donor site morbidity. The use of structural allografts has been more critical in reconstructive fusions. In recent years, alternatives to autogenous bone graft, including recombinant human platelet-derived growth factor-BB (rhPDGF-BB), have yielded promising results. In some instances, the use of alternative agents in both hindfoot and ankle fusion procedures has been shown to demonstrate higher fusion rates without the need for additional surgical incisions to harvest autologous bone, thereby avoiding the potentially chronic pain and/or alternative donor site morbidities frequently associated with autograft harvest.18
In the case presented, in-situ subtalar arthrodesis was recommended given the patient’s relatively preserved calcaneal height and anatomy as well as the desire to minimize further surgical risk. This was achieved with two parallel partially threaded large-fragment screws. Post-operatively, he was initially made non-weight bearing in a short leg cast and gradually transitioned to a walking boot at 6 weeks. By 4 months, he was fully weight-bearing in sneakers. He did undergo screw removal 7.5 months after surgery for symptomatic hardware. At the time of the last follow-up visit, 8 months after his fusion surgery, he reported a 50% improvement in his overall symptoms and function. He was fully weight-bearing and enabled to return to full work duties without restriction.
Nothing to disclose.
The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.
- Rammelt S, Bartoníček J, Park K-H. Traumatic Injury to the Subtalar Joint. Foot Ankle Clin. 2018;23(3):353-374. https://doi.org/10.1016/j.fcl.2018.04.004
- Radnay CS, Clare MP, Sanders RW. Subtalar Fusion After Displaced Intra-Articular Calcaneal Fractures. J Bone Jt Surg. 2010;92:32-43. https://doi.org/10.2106/JBJS.I.01267
- Csizy M, Buckley R, Tough S, et al. Displaced Intra-articular Calcaneal Fractures. J Orthop Trauma. 2003;17(2):106-112. https://doi.org/10.1097/00005131-200302000-00005
- Buckley R, Leighton R, Sanders D, et al. Open Reduction and Internal Fixation Compared With ORIF and Primary Subtalar Arthrodesis for Treatment of Sanders Type IV Calcaneal Fractures. J Orthop Trauma. 2014;28(10):577-583. https://doi.org/10.1097/BOT.0000000000000191
- Potter MQ, Nunley JA. Long-Term Functional Outcomes After Operative Treatment for Intra-Articular Fractures of the Calcaneus. J Bone Jt Surg. 2009;91(8):1854-1860. https://doi.org/10.2106/JBJS.H.01475
- Mahmoud K, Mekhaimar M, Alhammoud A. Prevalence of Peroneal Tendon Instability in Calcaneus Fractures: A Systematic Review and Meta-Analysis. J Foot Ankle Surg. 2018;57(Radiographics 25 2005):572-578. https://doi.org/10.1053/j.jfas.2017.11.032
- Richter M, Kwon J, DiGiovanni C. Foot Injuries; in Skeletal Trauma: Basic Science, Management and Reconstruction. 5<sup>th</sup> Edition. Chapter 67 p. 2251-2387. Elsevier Inc. 2015.
- Aston D, Detland J, Otis J, Kennealy S. Motion of the Hindfoot after Simulated Arthrodesis. J Bone Jt Surg. 1997;79(2):241-246. https://doi.org/10.2106/00004623-199702000-00012
- Hollman EJ, van der Vliet Q, Alexandridis G, Hietbrink F, Leenen L. Functional outcomes and quality of life in patients with subtalar arthrodesis for posttraumatic arthritis. Injury. 2017;48(7):1696-1700. https://doi.org/10.1016/j.injury.2017.05.018
- Hungerer S, Trapp O, Augat P, Bühren V. Posttraumatic arthrodesis of the subtalar joint – outcome in workers compensation and rates of non-union. Foot Ankle Surg. 2011;17(4):277-283. https://doi.org/10.1016/j.fas.2010.10.003
- Ziegler P, Friederichs J, Hungerer S. Fusion of the subtalar joint for post-traumatic arthrosis: a study of functional outcomes and non-unions. Int Orthop. 2017;41(7):1387-1393. https://doi.org/10.1007/s00264-017-3493-3
- Rammelt S, Grass R, Zawadski T, Biewener A, Zwipp H. Foot function after subtalar distraction bone-block arthrodesis. Bone Joint J. 2004;86-B(5):659-668. https://doi.org/10.1302/0301-620x.86b5.14205
- Coetzee CJ. Treatment of Hindfoot and Midfoot Arthritis, in Mann’s Surgery of the Foot and Ankle. Chapter 20, pg. 1008-1036. Elsevier Inc. 2014.
- Thordarson DB. Fusion in Posttraumatic Foot and Ankle Reconstruction. J Am Acad Orthop Sur. 2004;12(5):322-333. https://doi.org/10.5435/00124635-200409000-00007
- Rungprai C, Phisitkul P, Femino JE, Martin KD, Saltzman CL, Amendola A. Outcomes and Complications After Open Versus Posterior Arthroscopic Subtalar Arthrodesis in 121 Patients. J Bone Jt Surg. 2016;98(8):636-646. https://doi.org/10.2106/jbjs.15.00702
- DeCarbo WT, Berlet GC, Hyer CF, Smith BW. Single-Screw Fixation for Subtalar Joint Fusion Does Not Increase Nonunion Rate. Foot Ankle Specialist. 2010;3(4):164-166. https://doi.org/10.1177/1938640010368992
- Chuckpaiwong B, Easley ME, Glisson RR. Screw Placement in Subtalar Arthrodesis: A Biomechanical Study. Foot Ankle Int. 2009;30(02):133-141. https://doi.org/10.3113/FAI-2009-0133
- DiGiovanni CW, Lin SS, Baumhauer JF, et al. Recombinant Human Platelet-Derived Growth Factor-BB and Beta-Tricalcium Phosphate (rhPDGF-BB/&bgr;-TCP). J Bone Jt Surg. 2013;95(13):1184-1192. https://doi.org/10.2106/jbjs.k.01422
Cite this article
Ingall EM, Ibrahim IO, Uzosike AC, DiGiovanni CW. Subtalar arthrodesis for post-traumatic subtalar arthritis. J Med Insight. 2021;2021(122). doi:10.24296/jomi/122.
Table of Contents
- Skin Marking
- Sinus Tarsi Approach
- Identify and Retract Peroneal Tendons
- Identify Subtalar Joint
- Scrape Arthritic Cartilage
- Open Joint Space
- Perforate Subchondral Plate
- Identify Gerdy's Tubercle
- Harvest Graft
- Pack with Allograft
- Add Autograft to Joint Space
- Drill Through Calcaneus
- Measure for Screw Length
- Insert Screw
- Repeat for 2nd Screw
- X-ray Confirmation
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.