Implantes iFuse: Imágenes a los 3/4/5 Años

Leonard Rudolf, MD

El Dr. Leonard Rudolf, de Lebanon New Hampshire comparte imágenes de 3, 4 y 5 años de aquellos de sus pacientes que se sometieron a la intervención quirúrgica de la articulación sacroilíaca con iFuse Implant System.

Divulgaciones: El Dr. Rudolf es un consultor remunerado, con participación accionaria y realiza investigaciones clínicas para SI-BONE Inc.

Todos los datos de pacientes presentados fueron de pacientes tratados por trastornos de la articulación sacroilíaca o sacroileítis degenerativa.

El iFuse Implant System está previsto para la fusión sacroilíaca en afecciones como la disfunción de la articulación sacroilíaca, que es resultado directo de la desalineación de la articulación sacroilíaca y de la sacroileítis degenerativa. Se incluyen afecciones cuyos síntomas comenzaron durante el embarazo o en el periodo periparto y han persistido después del parto durante más de 6 meses. Existen riesgos potenciales asociados con el iFuse Implant System. Es posible que no sea adecuado para todos los pacientes y es posible que no todos los pacientes se beneficien. Para obtener información sobre los riesgos, visite:

El Dr. Reckling es un empleado de SI-BONE Inc.

"I'm Leonard Rudolf, a practicing orthopedic surgeon doing lumbar spine surgery in Lebanon, New Hampshire, and I'd like to share with you some of my experiences using the iFuse implant to treat patients with sacroiliac joint problems. The purpose of my talk is to review with you some of my experience with patient outcomes at 3, 4, and 5 years.

The iFuse implant has been used for several years now and we're now starting to see some outcome studies. Dr. Cummings has prepared a series of patients with one year follow-up and he documented high patient satisfaction with a low complication rate. Dr. Sachs, also a one year follow-up showing the outcomes of 40 patients with excellent patient satisfaction and a low complication rate.

Miller reviewed complaints and found that there was a low revision rate of 1.8% and an overall complaint rate of only 3.8% for over 5,000 patients treated. I presented my first 50 patients with a minimum of 24 months follow-up, documented the surgical procedure. The outcomes documented significant pain improvement and most patients were satisfied with the results of surgery.

As an orthopedic surgeon, I also do lower extremity surgery as well as lumbar spine. And very frequently, when patients are anticipating a procedure with an implant, very appropriately they'll ask me, "How long will this last?" This 67-year old patient presented to me with right SI joint degenerative joint disease with pain that we confirmed as pain generator with an image-guided injection. After he had had an extensive amount of non-operative management with physical therapy and medications, he elected to undergo the iFuse procedure.

And here is an example of somebody that may not just have one pain generator. I'd like to point out that he does have some L5-S1 facet sclerosis in addition to a degenerative joint, which we also see on the opposite side. So here's an individual that fits the category of the lumbar SI hip joint axis. He's had problems with degenerative arthritis in the hip. He has facet arthropathy and he also had SI joint problems.

I like to share with you a series of images of a CT scan that I got immediately post-operatively. This slide represents the axial view of the uppermost implant crossing the SI joint ilium into the upper part of the sacrum. This same implant just a little bit lower showing its penetration into the sacral alar area. This picture is a sagittal image of the four implants that are on the iliac side, and over here, these implants are on the sacral side.

Now, I like to point out a couple of important points here because we're gonna see this consistently through the remaining part of my presentation. And that is that the triangular titanium implants generate a artifact on imaging that does not represent loss of bone or should be interpreted to suggest loosening. We have consistently seen on all of the CT scans of the patients that we did iFuse that there is this area of radial lucency at the points of the implant. 

And notice that this corner is not quite yet all the way in bone yet we see the little area of radial lucency or this artifact. Obviously, this cannot represent bone loss because it's not even in bone. This is an artifact and we've reviewed with other people that are very familiar with the physics of radiology that these triangular implants, whether they're stainless steel or titanium, can generate these areas of radial artifact.

These CT scan images are representative of a similar location that we saw at the immediate post-op. So here we are looking at the upper implant as it first presents across the ilium and then farther within the ala of the sacrum. I like to point out that we are seeing in several areas points of increased bone density that we hope will then provide for biologic integration.

We really see this much better on the sagittal views and I'm gonna suggest that to truly visualize the areas of increased bone density along the walls of our implant, we see this on the sagittal views. This is the image on the iliac side and here we come over to the sacral side. On both sides of the SI joint, meaning both sacrum and ilium, we have areas along the walls of the implants of increased bone that would represent biologic fixation.

This patient had x-rays at 1 year, and notice there is that radial artifact on the edge. And I can understand how some might interpret this to be loosening, but this is now the 5-year image. Notice the areas of increased bone that we see here. Other than this one little spot here, that radial lucent area is truly non-progressive, and the patient clinically has done very well.

This 36-year old female presented to me having 7 years of back and sciatic pain that was treated presumably for sciatica. She really did not respond to any of the non-operative measures that were offered. When I evaluated her, I thought that she might indeed have SI joint problems and she had an unstable joint secondary to post-partum laxity. And the SI joint as pain generator was confirmed on this CT-guided injection.

This is a radiograph of this 36-year old immediately post-op documenting the three iFuse implants. This CT scan, axial view, shows the upper implant and then a second implant. The coronal view shows the presence of the upper and the lower implant. But I would like to point out to you that there was this area that looked like a hypertrophic pseudarthrosis. This ligamentous unstable joint was crying desperately to stabilize itself.

The post-op sagittal views, this is the sacral and the iliac side. This 1 year post-op film shows the three implants. We do see the area of radial artifact that can sometimes be misinterpreted to mean loosening. Clinically, she was doing very well. This 1 year post-op CT image shows the increased bone density. Now, clearly we know that not necessarily the entire length of the implant will have increased bone density. But if there is areas on both sides of the joint, and we can see a considerable amount of bone at the entry site inferiorly here as well on both sides of the joint, this would be strongly suggestive for an implant that is solidly in-bone with biologic fixation.

This sagittal view, again, represents the areas of increased bone density on all three sides of the walls. Yes, there is the radial artifact at the point. Maybe not all of the wall has bone that is enlarged along it, but certainly on all three sides, this is the iliac side and the sacral side. And again, clearly increased bone density. This same patient now at 4 and then 5 years. There's no apparent suggestion for progressive loosening or lucencies of these implants. The bony bridge inferiorly is complete. She has a very stable SI joint.

This 66-year old female presented with degenerative SI joint problems that we confirmed with an image-guided injection. Unfortunately, she was refractory to non-operative management and elected to undergo surgical treatment with the iFuse implant. This 1 year post-op film shows the three implants and when I first observed it, I was concerned when I saw that area of radial lucency at that implant level.

This 1 year post-op CT showing the coronal view documented clearly a lot of increased bone density. The sagittal views showed considerable increased bone on both the iliac and along the walls on the sacral side. At 4 years after surgery, the images really do not show any change in the overall appearance of that area that looked like radial lucency. Perhaps this was radial artifact.

On the occasion of her opposite side becoming symptomatic, the plain film for the CT again showed this non-progressive radial lucent area. We had confirmation of the opposite side being symptomatic. And I'm gonna share with you now the upper, middle, and lower implants on these axial view documenting very nice bone density with no apparent lucency or loosening of these implants, a 5 year CT documenting excellent fixation.

This 64-year old female presented with degenerative joint, confirmed with the injection. Refractory to non-operative management and she elected the procedure as well. Here we are at 3 years after surgery, and once again, we can see some bone density but we also can see that radial artifact. Unfortunately, she had some osteopenia that evolved to osteoporosis and three years after the surgery developed a vertebral body compression fracture that I treated with kyphoplasty. She had excellent response to her back pain.

When she developed some abdominal problems, I came across an abdominal CT that represented images 4 years after her iFuse surgery. This axial view of the upper implant shows no lucency and good evidence of increased bone density. We do see that at the lower implant as well. The sagittal view, a little bit blurry, but nonetheless documenting areas of increased bone density and consistently we see those little spots of radial artifact at the corners.

At 5 years after her iFuse implant, unfortunately she developed a subtrochanteric fracture due to Fosamax and despite the osteoporosis in this patient, the iFuse implant has preserved its position and we do not see loosening despite her condition of osteoporosis.

This 78-yead old female presented to me with adjacent segment disorder degenerative right SI joint problems. She had had a lumbar fusion for degenerative scoliosis. Notice also that she has some early degenerative arthritis of her hip. Again, a classic case of the axis of lumbar SI hip. Where is the pain generator? Clinical examinations suggested strongly it was the SI joint. Confirmation was determined with an image-guided injection.

These operative x-rays document the three implants to treat her SI joint. At 1 year post-op, AP and lateral views, this CT documents on this axial views the upper, the middle, and the lower implant crossing the SI joint. Please observe the areas of increased bone density along the walls. The sagittal view confirms the increased bone density on the walls and we still see consistently the areas of artifact at the points.     

Here she is 5 years post-op. Now she's 83. She actually came to see me because her hip arthritis has gotten worse. Her SI joint continue to be asymptomatic. No change in the appearance of these iFuse implants to suggest any kind of loosening.

This 64-year old had left SI joint degenerative joint disease that was treated with the iFuse implants. The plain film on the left of the screen shows the three implants and as you can tell, the lowest implant is situated in between the S1 and the S2 neural foramen. Now, sometimes the direction of the x-ray bin can lead one to think that perhaps one is actually a little too medial or in a neural foramen. Yet av-, as we look at the CT on the right side of the screen we can see that the end of the implant is well lateral to the actual path of the S2 neural foramen. We will see on further slides the sense that maybe this same client is in the S2 foramen, but it really isn't as we know.

This post-op CT represents the axial views of the left SI of the upper, middle, and lower implants. At 1 year post-op, we do see the radial artifact, but perhaps also this might represent some radial lucency. At 1year, she was asymptomatic. At 4 years, she came to see me. There is that area of lucency but no change in the position or the overall appearance of the other implants. This was not a progressive lucency and symptomatically she was doing very well. The 5 year x-ray, no progression of the lucency, clinically doing very well.    

I have two patients that did have excellent improvement at the initial post-op that developed 1 year later to novel pain. It seemed to be stemming from the SI joint and an injection confirmed the pain generator. This CT documents a posterior position of the lower implants with sacral side lucency. This CT scan showing the lowest implant with surrounding areas suggestive for lucency.

On the axial view, we can see that this implant is short, not penetrating into the sacrum, and therefore, not controlling the sacral side of the joint even though we do see some bone density on the iliac side. Because of the posteriorly positioned implants, it was possible to place two more implants more anteriorly. The patient did very well subsequent to the revision surgery.

So in conclusion, I'd like to suggest that if properly positioned, these implants have good predictability for long-term success as I've shown on radiographic and CT imaging. Thank you."