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Board Review Surgery

Use of the Sidekick External Fixator for Triple Arthrodesis

Harold Schoenhaus, DPM

Harold Schoenhaus, DPM discusses the indications and goals for triple arthrodesis and the advantages and possible complications of using the sidekick external fixator for triple arthrodesis procedures. Dr Schoenhaus supports his discussion with case examples.

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Goals and Objectives
  1. List the indications for triple arthrodesis
  2. Review the goals of triple arthrodesis
  3. Recognize the limitations of triple arthrodesis
  4. Describe the procedure for triple arthrodesis with application of the sidekick fixator
  5. Recognize the advantages and disadvantages of the sidekick device
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  • CPME (Credits: 0.5)

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    Release Date: 03/16/2018 Expiration Date: 12/31/2018

  • Author
  • Harold Schoenhaus, DPM

    Surgical Editor for PRESENT e-Learning
    Penn-Presbyterian Medical Center
    Philadelphia, PA

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  • Lecture Transcript
  • All right. This is an interesting section, because what we're going to do is talk a little bit about triple arthrodesis, and there's been certainly different approaches, surgical approaches, methods of fixation, and I'm not sure anything is, has been identified as THE best in dealing with triple arthrodesis. But what I'm going to do is start off by going over a few important factors and points about triple, where it's indicated, and Dr Kalish is going to have a few comments, and Dr LaPorta, and obviously anybody who has any questions or comments, please feel free to engage us in any type of controversial component to that.
    Indications for triple: painful joint secondary to arthrosis, post-traumatic arthritis, DJD, rheumatoid arthritis, tarsal coalition, chronic instability, secondary CMT, ankle instability, posterior tibial dysfunction, collapsing pes planus, peroneal spastic flat foot, other neuromuscular diseases, and deformities such as uncorrected congenital clubfoot, Charcot neuroarthropathy, talipes equinovarus.
    Limitations: triple arthrodesis is a technically demanding procedure. You need to have a spatial component of thought as to what you're going to try to do to reorientate the foot into a position that's going to be plantigrade, acceptable, and hopefully diminishing significant pain from the foot with the patient. There is a slow recovery to it. It takes a certain period of time for joints to fuse, and after that we've got to deal with extensive physical therapy to rehabilitate the leg and allow this patient begin ambulation.
    It's considered for salvage only � not to be used when soft tissue procedure or lesser types of arthrodesis will correct the problem.
    Goals � correct cavus, correct planus. Resist muscular imbalance. Relieve pain of the arthritic joints and create a stable neutral plantigrade foot. Those are the goals.
    Now, I'm not going to bore you with historical perspective. Methods of resecting the joints are important. The method that you're going to use as to which joints you're going to resect first and how you're going to stabilize them before you ultimately fuse them, is also going to be important.
    Anatomic dissection. Obtain adequate exposure, use hemostasis, using atraumatic techniques. As I stated earlier, this is a technically demanding procedure. If you use a double incision approach, medially and laterally, you're going to connect, you're going to be actually looking through the foot, so many structures are going to be in position to be adversely affected by what you're doing. So over the years, I've attempted to go in one direction, one incision, to avoid multiple complications.
    Obviously you need to be aware of the skin incision you're going to use. I stated earlier � big surgeons make big incisions. Adequate exposure � I hate pulling on tissues which creates, which leads to post-operative soft tissue complications in healing. We see the same thing happening when you're doing ankle joint surgery and ankle joint replacement. The care has to be taken of the soft tissue window. The soft tissue we

    neglect and ignore, and you take these big retractors, army navies, and you're pulling on tissue � it's traumatic.
    The sections through the tissue layers and planes are important. You want to be sure obviously to avoid any of the important structures, neurovascularly, tendons, etc. Incisional approaches � that depends upon who you read and where you train, and I just like to consider my incisional approaches based upon the anatomy that's present. Avoiding the major structures that can create problems.
    Fixation techniques � everything has been used to fix bone. It's no different than any other arthrodesis site, whether you're going to use screws, staples, pins. The device that I've been using lately is what you're looking at there, this is an external fixation device, it's called the sidekick. I find this to be extremely effective. I like this method of fixation because it allows for complete stabilization and compression of the joints, and does not require a cast. So the patient wearing this device is able to dorsiflex and plantar flex their foot. They can even shower after a couple of weeks. It's not a weight-bearing device. I do not allow my triple arthrodesis to bear weight.
    So let's take a look. Here's a case of a patient who has had other surgery done. You can see this foot is an absolute disaster in itself. Even the forefoot reconstruction is not effective. Significant degenerative disease in the mid-tarsal and subtalar complex � it's painful. This is the typical incision approach that I make at this point in time. I come from below the lateral malleolus, over the sinus tarsi, over to the base of the fourth and fifth mets, even extending maybe a little toward the third. That approach is going to allow me complete exposure to both the subtalar joint, calcaneal cuboid joint, and talonavicular articulation.
    So we just start reflecting down and before once we expose the extensor brevis and take it away from the sinus tarsi and reflect it distally, you're looking at this PCC joint, and right posterior to the sinus tarsi is your subtalar joint.
    Now, to remove or resect the joint surfaces, I do start with the subtalar complex first. You can use osteotome and mallet. I take the lateral portion of that talus that hangs down right off so that I can see directly into the joint. An impact osteotome is what I like to use. It's a shovel that just goes front and back. MicroAire makes it. And you can actually follow the contour of the subtalar joint and the calcaneal cuboid joint if you want to attempt to do what we refer to as an in site two type of fusion. You've got to get down past the subchondral bone. If you're going to leave the subchondral plate within the joint complexes, drill the living daylights out of it so that you will allow for angiogenesis and ultimately osteogenesis to take place to lead to the fusion.
    Right. Here we are, just exposing the subtalar joint. You can see it's a rather large joint. I usually put a smooth toothed laminar spreader into the sinus tarsi. You've got to cut through the interosseous talocalcaneal ligament, put your laminar spreader in and open up the subtalar joint posteriorly. And then the use of the osteotome or the MicroAire processor that shovel away the abnormal tissue.


    Now, once I have done that, I am going to be prepared to go and resect the CC and the TN joint. Now, if we take a lateral X-ray or an oblique X-ray, what do we call that line that represents the mid-tarsal complex? It's the simoline. And very interestingly, with this surgical approach, you can see the entire subtalar complex posteriorly, and then the mid-tarsal joint, both talonavicular and CC joint. You reposition the foot in where you want it to ultimately be; you can pin it if you wish; and then I can resect across the entire midfoot from lateral to medial. And here it is with a rather large saw, just coming across the entire mid-tarsal complex, removing the head of the talus, which is that nice little cap, and you take this off in complete apposition � one side to another. I always marvel at watching somebody do a triple from both sides, medial and laterally, and then putting the surfaces together and everything was congruous. I'm probably a poor surgeon because I always was teeter-tottering. Take off a little more here, a little bit more here, until you finally get it together. And with this one incisional approach, I avoid that from happening. And there's that laminar spreader in there.
    Now, that's the resected portion of the new mid-tarsal joint which is going to be fused. And you can see you have complete visualization medially and laterally. And you use soft protectors up over the top of the foot so the neurovascular bundle on the dorsum is separated and held up with soft tissue types of retraction. And you just make your cut accordingly.
    I do like to use orthobiologics, whether I'm using sponge, whether I'm using any of the other orthobiologics to assist in any areas of incongruity or any cysts that might have been present, to fill the voids so that I get excellent apposition of the bone.
    I temporarily fix the subtalar joint with the Steinmann pin, coming directly under the heel, place the calcaneus and the talus in the exact position that you want that foot to be in, and then realign or align your mid-tarsal complex and hold it in position with pins.
    Once that temporary fixation is established, and you're satisfied with the position, you take two trans-osseous pins in preparation for your external fixator. One trans-osseous pin goes through the neck of the talus, from medial to lateral or lateral to medial; another trans-osseous pin is going to go through the calcaneus. And then you're going to place two additional pins, one in the navicular and one in the cuboid. And here we are putting those trans-osseous pins across the foot.
    I use a cannulated approach and technique to do it, so I take a small K-wire first. The pins have to be perpendicular to the direction of the foot, the long axis of the foot. And the trans-osseous pins of the calcaneus and the neck of the talus, they have to be parallel to each other and perpendicular to the foot. So I put a K-wire in first, I get an X-ray, and then it's a cannulated drill that goes directly over � this is the technique that I kind of developed with one of the companies. The drill itself, the bit that's going to go through the trans-osseous component, is cannulated half way through. So you just simply follow your guided pin right across the foot.


    All right? So now you can see on the bottom of this picture, where I have two parallel pins, one through the calcaneus, one through the neck of the talus. You then apply the frame. And here you can see the frame being applied. Once the frame is applied, both on the lateral and medial side, you then place your final two pins, one in the navicular and one in the cuboid. Now you're going to be able to get compression on both the medial and lateral sides of the foot. Once I'm satisfied that the pins are in excellent position, I take the frame off, suture the incision closed, and now you are ready to simply apply the compression across the three major joints. So with the one incision, has provided me with excellent exposure. And I've heard people say, well, how are you going to get on a severely pronated foot? You'll never get the medial side coming across by the navicular. It's not true. You get a majority of the navicular and the talus that are resected and realigned. You don't need to come medially.
    Here are the pins in place. The beauty of external fixation is, as bones start to absorb, certainly with some osteonecrosis that you create with resection of joint, you're going to get some absorption. The external fixator allows you to get additional compression while the patient is back in the office.
    So the sidekick is just another approach � I'm not going to go into subtalar fusion, but � the sidekick is just another method of external fixation to allow for triple arthrodesis to get an ultimate result.
    Complications � any time you do any type of reconstructive surgery, the typical complications that we see are there. Malalignment, malunion, non-union, pseudoarthrosis at the sites, pin track infections, which with this type of device are minimal � those are hefty pins. I like to use these biopatches over the pins to prevent it. Your dissection technique has to be careful that you don't involve any of the neurovascular structures. Because certainly you can create nerve related problems.
    I like to think that when I do a triple I put that foot neutral to slightly evert it in the rear foot, so that there is a little bit of a pronated position to that foot. A cavus foot is a disaster. That foot has to have a little bit of pronation left in it to enable a person to ambulate properly.
    So I'm going to stop at this point, and I'm going to call upon Dr Kalish to share with us some of his thoughts on triple arthrodesis. Thank you.