Posterior Tethering for Early Onset Scoliosis

Speaker 1Hi, I'm Ala Azmi Ahmed, pediatric orthopedic surgeon, and happy to share with you our experience of surgical management of Early onset scoliosis.

Speaker 1Cases through active Aic correction, what what we call it the APC technique.

Speaker 1Early onset scoliosis, as we know, is a complicated health problem due to heterogeneity, presence of associated morbidities, higher complications than idiopathic Spine deformity, the need of a multidisciplinary Approach besides the implant expenses, and most importantly is the repeated surgeries that the child and the family are having difficulty to cope with.

Speaker 1And the treatment is shifting now more and more to decrease the repeated surgeries because of the effect on the child and the family.

Speaker 1Unfortunately, none of the growth friendly techniques have shown real superiority and the rate of complications is still high.

Speaker 1The main aim of surgical correction, as we know, is through growth preservation technique.

Speaker 1That is to maintain the mobile growing Spine and preserve lung growth with minimal complications.

Speaker 1And most common surgical management falls under one of three philosophies.

Speaker 1Distraction-based system like the vector, conventional growing rods, and the magic magnetic growing rods.

Speaker 1And the guided growth system like the Luke and Sheila, Luke Trolley and Sheila, and the compression-based system like the vertebral staples and tethering.

Speaker 1So here we can share with you our experience about the APC again. What's the APC? It's a hybrid, simply a hybrid of guided growth and compression-based philosophies for management of the growing Spine deformity.

Speaker 1This technique consists of replacing the epical fusion that we can see in the traditional shiva.

Speaker 1With unilateral compression.

Speaker 1In the convex side via pedicular screws.

Speaker 1So we have here supposed to be the most wedged vertebra, and we'll compress the most wedged vertebra on the convex side. It's a kind of tethering technique by one screw above, one screw below. So accordingly, this compression is meant to hold the growth of the most wedged vertebra.

Speaker 1On the convex side and allow the ratio of the concave.

Speaker 1And convex side to increase over time. Thus it reduces the height of the vertebral, reduces the vertebral wedging on the concave side. So biomechanically it will allow the active compression based intervention at the apex in accordance with Hooter Wolkmann's law.

Speaker 1And that will also decrease the incidence of crankshaft phenomena since it's not a posterior fusion like in the sheela.

Speaker 1And it maintains the growth posteriorly, but it

Speaker 1do it through the tethering technique.

Speaker 1This technique also avoids the need for pedicular screw fixation on the concave side, which we know how sometimes in a 4 or 5 year old child is very hard and very risky, and the need of risky osteotomies to correct the apex of the curve with fusion like in the shield.

Speaker 1Here we can see uh.

Speaker 1Examples of the Sheila and the APC technique and the difference we can realize on the left there is a complete fusion with 6 screws at 3 levels in the sheila and the sliding of the rods approximately 2 centimeters, approximately and 2 centimeters 3 according to Dr. McCarthy's.

Speaker 1A protocol.

Speaker 1On the right we can see the APC of a 7 year old man. You can see the red lined vertebra, which is the most wedged vertebra that we know with preoperative planning with the X-ray and a 3D CT scan.

Speaker 1And we put one screw above in the vertebra above, one screw in the vertebra below on the convex side.

Speaker 1So we assume that this tethering will remodel the most wedged vertebra.

Speaker 1And with connecting the tethered rod with, and usually we use the 5.5 rod for tethering, and we connected proximity and disy with proximal anchors and distal anchors, and you can use 5.5 or 4.5 rods, whatever suits.

Speaker 1And we connect them with a domino or you connect them with a Shia system, Sheila screws, but we connect them now with a domino that will give a chance for sliding of the rods, as we can see proximity and distance without going through recurrent surgeries of distraction.

Speaker 1And also here on the most right one.

Speaker 1You can see that you use either hooks like on the left one of the APC approximately, or you can use screws, whatever you want.

Speaker 1As we can see,

Speaker 1This is an example of the APC in the OR, the yellow circled screws.

Speaker 1Are screws inserted in the convex side of the vertebras above and below the most wedged one.

Speaker 1Which will give the tethering effect that will decrease the growth of the convex part of the most wedged vertebra.

Speaker 1Unlike the concave part, which is not touched, and still the muscles are covering is the muscles are covering it.

Speaker 1Proximal

Speaker 1And distal anchors.

Speaker 1Here are connected.

Speaker 1To the tethered rod via dominoes that will permit sliding of the rods without the need of distraction.

Speaker 1On the concave side, we connect the rods of the proximal and distal anchors with dominoes that also will permit sliding of the rod that is usually having 4 centimeters length to slide.

Speaker 1This is an example of rod sliding with a patient that we did, but without dominoes with Sheila screws disy as we can see, and on the left side is the case immediate postoperative with the rod distilly about 4 centimeters in both sides.

Speaker 1And after 2 years we can see the difference of the rod length distal to the sheila screws. That means that the growth of the Spine was so good.

Speaker 1That the sliding of the rod within two years on the concave side, it decreased from 4 centimeters to 1.5 centimeters, and on the convex side it decreased from 4 centimeters to 2.2 centimeters.

Speaker 1This is how we evaluate precisely the wedging of the most wedged vertebrae.

Speaker 1Always we do a 3D CT scan preoperatively.

Speaker 1And in the last follow up, we do a 3D CT scan to be sure about the modulation of the vertebrae. Here we can see that from the CT scan.

Speaker 1The first one on the left side.

Speaker 1is that we take the height of the concave part of the most vertebra.

Speaker 1And we take the height of the convicts.

Speaker 1And it was

Speaker 174%

Speaker 1And after 18 months we can realize there is a modulation.

Speaker 1And the concave side.

Speaker 1Growth was

Speaker 1Much more than the convict side growth during that time.

Speaker 1Which gave the person the same ratio became 81%.

Speaker 1The posterior Approach is the most popular Approach for most Spine surgeons, and when we use the tethering through posterior, not Anterior approach, it will be more comfortable for most Spine surgeons. Also, the distance of the rod to the apex of the Spine deformity is minimal because we use particular screws on the convex side which will give more control to our correction.

Speaker 1No direct compression on the intervertebral disc, as we can see, we didn't touch actually the discs of the most wedged vertebra proximity or distally, and we just put screws on the vertebras proximal and distal to the most edged vertebra, unlike the staples which have some degeneration of the discs when you use it.

Speaker 1You can adjust also the rod to the Spine geometry, and this is one of the main advantages is that you are, you are just using regular implants.

Speaker 1You are using regular rods. You are using regular screws. You are using regular hooks. You are using regular dominoes which give an advantage that you can do it with without being stuck to a specific company or an expensive implant that you need to do this process with.

Speaker 1The APC has the same concept of the sheila. Because of that, we first called it a modification of the sheila, the same concept of that when you do Surgery, you need to control the apex of the curve, unlike the distraction methods. But there are some benefits over the sheila. We don't do osteotomies because we are not fusing the posterior part.

Speaker 1And 2 screws at the apex instead of 6, which is financially is a privilege, but also it is less risky when of course we know that using screws on the convex side is much, much safer than putting screws on the concave side.

Speaker 1And the possibility of the crankshaft is less with our APC technique since we are controlling the epics through growth, not fusion. And in the literature, Dr. McCarthy with his last study in 2017, about 5 years follow up of his cases, he had 62% of the cases that had crankshaft phenomena. Since you are doing a fusion.

Speaker 1Posteriorly, so you are stopping the height but not stopping the growth anteriorly, which will increase the chance of crankshaft in the sheela, unlike preserving the growth posteriorly and anteriorly, and you'll go through modulation which will decrease this incidence, which is very important.

Speaker 1The first paper published about our APC technique.

Speaker 1was in 2017 and since then,

Speaker 1We published 6 papers in peer-reviewed journals about our experiences and our data and our results of the APC technique.

Speaker 1One of the papers was comparing the APC with the traditional growing rod that the same surgeon have done.

Speaker 1It was published in the Spine Surgery and Related Research.

Speaker 1We can see here from the parameters that there is no statistical significance.

Speaker 1In all parameters except for the follow-up time, which is 5 years in the transition growing rods and 2.5 years in the APC technique, which is understandable.

Speaker 1But Other parameters, there is no statistical significance, acknowledging that there's a major difference that the APC, you don't need to get the child every 6 months to do distraction like the traditional growing roots.

Speaker 1Also for the complication, we can realize that the APC had less complication, 5 in comparison to 13 of the traditional growing rods, but we must acknowledge that the follow up time is nearly doubled in the tradition growing rods.

Speaker 1We are doing a

Speaker 1In the Spine lab of the biomedical engineering department in the University of Toledo.

Speaker 1A virtual computational spinal study about the APC technique.

Speaker 1And we had the Primary data, which is very encouraging and goes with the clinical data that we have.

Speaker 1With the experience that we gained through time, we try to improve the APC surgical technique that will decrease the fusion incidence to the minimum.

Speaker 1And involve minimal invasive Surgery also and this technique.

Speaker 1As we see here, this is a very young female who's having severe scoliosis.

Speaker 1And the vertebra, the most wedged vertebra, was selected in the preoperative preparation.

Speaker 1Which is lined in red.

Speaker 1Here we can see on the right side, the two small incisions which are encircled in blue. These are small incisions that we use to put the screws percutaneously and the convex side of the vertebras above and below the most twitched vertebra, which will decrease the incidence of fusion to the minimum because we didn't do disruption or minimal disruption of the tissues around the apex.

Speaker 1And of course we connect, as you can see from the middle slide, connecting the proximal ancestor anchors with dominoes that will give a chance for sliding of the rods.

Speaker 1Uh, in the convex and the concave side.

Speaker 2So, uh, we did put, now the tethering technique, we have put one screw at T12, the pedicle at T12, and one screw at the pedicle of L2. And here's L1, we didn't touch it on the convex side.

Speaker 2And we didn't touch anything on the concave side, so this is the tethering technique instead of a complete fusion of the apex of the Spine. So it will cause a tethering that will spontaneously remodel the Spine on the Other side, the wedged vertebra. Here you can see these are the proximal anchors.

Speaker 2And these are hooks, uh, that are in clawing fashion. Two going downwards, one going upward on the ribs, rib 567, and these are the distal anchors because the patient is non-ambulatory, and she's having severe scoliosis, uh, in the lower, uh, in the lumbar region, thocolumbar region. So, I usually put two iliac screws instead of one iliac screw.

Speaker 2Uh, for more fixation, and then here are the tethering part.

Speaker 2Which are on the convex side, which was 80 degrees, we can realize that it has improved a lot and I just put on T12 and L2.

Speaker 2And I've put a 4.5 rod here. The tethering one is 5.5 rod system with 5.5 rod and 5.5 screws, and proximately and proximately and this history, we have 4.5 rods which are connected to the tethering part, tethering rod with a domino. The domino is 5.5, 5.5, so as this rod will slide in this piece.

Speaker 2And also this rod will slide in this piece, and these are both fixed on the tethering part, so there will be no movement on the tethering part.

Speaker 2And we can realize that the concave side has nothing here. We didn't touch the soft tissue all over the area. We didn't touch the Spine, and we have just put a sliding elongation, 4.5 rod with 4.5 rod, but you have an option to use

Speaker 15.5 rods proximity and industry also,

Speaker 2and

Speaker 2we usually put the rods so as to be at least 4 centimeters, so it will give the patient at least 4 years of lengthening without going through.

Speaker 2A distraction every 6 months.

Speaker 1Post operatively we can realize from the X-ray on the right that the 80 degrees became 39 degrees.

Speaker 1And also sitting is much better.

Speaker 1for the child, and she's much, much better compensated during sitting.

Speaker 1We need to avoid now for the technical considerations, we need to avoid sharp transitions in the structural geometry of the system that might lead to stress rising.

Speaker 1And minimize the contact of dissimilar material to decrease potential for corrosion.

Speaker 1And the rod diameter in the posterior system should be large enough to have the structural rigidity. Actually now we don't use at all the 4.5 rod as a tethering rod. We use even in a 4 year old child, we use a 5.5 rod.

Speaker 1As a tethering rod, you might use the proximal or distal rods as a 4.5 or 5.5.

Speaker 1But for the tethering rod, always use the 5.5 rod. It would be much better for correction.

Speaker 1So take home message. What's the message now? This technique, the APC, is a hybrid technique using unique benefits of two philosophies.

Speaker 1Done through a very popular Approach which is the posterior Approach for most Spine surgeons.

Speaker 1Similar correction parameters as conventional growing roads as we can see from our studies.

Speaker 1The possibility of crankshaft distal migration adding on is decreasing.

Speaker 1You can use regular Spine implants from any company that is affordable and cost effective, and that is a real privilege in low middle income countries, but also financially speaking, it's much better even in developed countries.

Speaker 1No risky procedure requires is required at the apex. No need of osteotomies. No need of putting screws in the concave side.

Speaker 1Thank you very much for giving time to listen to this technique, new technique, and I'm looking forward to share your ideas about it and your suggestions, your comments to improve our management for Early onset scoliosis children. Thank you.