Paul Slosar, MD - Orthopedic Surgeon - Daly City, CA
Dr. Slosar is a board-certified, fellowship-trained orthopaedic spine surgeon. He has been in practice for almost 20 years and is President of SpineCare Medical Group, Medical Director of the Spine Care Institute of San Francisco, and Co-Director and Director of Surgical Research for San Francisco Spine Institute.
Dr. Slosar has published and presented on numerous spine topics, instructs other surgeons on new technologies and techniques, is an editorial board member for several medical journals, and serves as oral board examiner for two surgery boards. He serves on the Board of Directors of The American Board of Spinal Surgery and The Spinal Research Foundation. The Medical Board of California has selected Dr. Slosar as an expert reviewer in spinal surgery. He also works in collaboration with companies to develop new technologies and improve spinal surgery techniques. He is the Medical Director at Titan Spine.
Q1: Why did you start using the Endoskeleton in the first place?
In 2009, the options available on a practical level included 3 common materials. First, smooth titanium; second, cadaveric bone; and the third, plastic (PEEK). The benefits these materials offered surgeons were limited because each had their own weakness. To be honest, I was somewhat skeptical in the beginning thinking there wasn’t anything different about the Titan Spine’s titanium versus the others that we had used.
First and foremost, as an orthopedic surgeon, plastic really never made any sense to me as a good material to place in between two bones if your desire was to get those two bones to grow together. We usually use plastic in orthopedics to keep things moving, so I never really adopted PEEK as a material that I would use commonly for fusion.
The second option was cadaveric or allograft bone. I have a long history of using allograft bone in the spine, as do many surgeons. A benefit it offered was that it was easy to find and reasonably plentiful. One downside is that it is cadaver bone and a number of patients have concerns about utilizing cadaver bone if there are other options available. Their concerns include the risk of a disease transmission or they really don’t want another person’s tissue in them. Another issue on a mechanical basis is that cadaver bone has a limited number of shapes and forms. However, a material, such as titanium, can be manufactured into more anatomic sizes. The bone that we used in the lumbar spine for fusions were femoral rings and they didn’t always fit well. Implants often collapsed or subsided inside the vertebrae, but it was a popular option at the time.
The third option - smooth titanium - was used commonly in the 1990’s but less so in the past ten years. This is primarily because titanium was manufactured into threaded cages that were shaped like shotgun shells. Those cages were problematic because you had to violate the vertebral endplate to insert them, which often led to subsidence. They also had a bad reputation for being difficult to assess for fusion on CT scans. They made it hard to see the bone because there was basically too much metal cage and not enough bone graft area. Due to these problems, surgeons moved away from smooth titanium and were using PEEK and cadaveric bone.
Once I became aware that:
- The surface technology being proposed as an adjunct to the titanium would be treated in a way that stimulates bone growth factors,
- Titan would manufacture implants that were more anatomic to sit on the apophyseal ring with large openings for bone graft and easy to assess fusion on CT, and
- This type of surface technology is essentially the standard in the dental industry, where arguably the mechanical forces are even higher than the spine and with less bone to work with.
Q2: What results have you seen from using the Endoskeleton?
As spine surgeons, we now have the benefit of two parallel bodies of scientific data that are emerging on this technology. First, we have the in-vitro science at the cellular level. The in-vitro science shows the cells necessary to form bone are stimulated and encouraged by the surface technology on the Titan Spine implants. Second, we have the clinical literature, which trails slightly behind the basic science, which is equally compelling. So what we were anticipating seeing based on the basic science, we are seeing on a clinical basis.
In my experience, patients’ outcomes with this device are outstanding. We have presented papers and posters of our scientific analysis of our clinical outcomes at several major spine meetings and the clinical data is very compelling. We are seeing excellent outcomes in the majority of the cases that we’ve treated. The patients have a range of clinical improvements anywhere from 50-70% reduction in their pre-operative pain, and we’re seeing these outcomes early, at six months after surgery. The reason I point that out is that not too long ago we told patients that it would take 12-24 months to heal their fusion. Advising them that it might take that long to feel better creates a profoundly difficult challenge for a patient who has undergone a back surgery thinking, “I have to wait 12-24 months to see if this worked.” Now we are telling patients to expect meaningful clinical improvements by six months, and those improvements are maintaining at 12 and 24 months based on the data we’ve reviewed.
As clinicians, we always look at the need to revise these fusion surgeries. Are we having to go back and do surgeries at the area that was previously fused, what we call a non-union or pseudoarthrosis? That’s when the bone doesn’t heal. In our practice as well as in our outcomes study, we’ve had no failed fusions with the Titan Spine implants. Now, I will offer that we have been using a strong biologic material at the beginning of the study called BMP. BMP is associated with very high fusion rates. As we’ve become comfortable with the Titan Spine technology, and proven it to be a safe and effective implant, we’ve throttled back on using this “nuclear powered” BMP biologic. Instead, we are using much less expensive and much less inflammatory biologics, and we’re maintaining good clinical results in these patients. We are using the surface technology of Titan Spine’s implant to encourage a patient’s own bone growth, independent of the biologic. I now believe we are much better able to bring meaningful cost savings to the market by reducing expenses associated with some of these bone growth factors and minimizing costly non-unions.
Q3: How many patients have you treated with the Endoskeleton at this point?
I can speak to our clinical outcome data. We followed 78 patients out to two-year follow-up. We’re also currently looking at all of our cervical data for the past 2.5 years, where we have 60-70 patients. I have transitioned away from cadaver bone almost entirely and utilize the Titan technology for almost all of my interbody fusions. Outside of the study, my interbody fusions are now almost 100% Titan surface technology implants.
Q4: How does the textured surface of the Endoskeleton impact the fusion process, in your experience?
If you look at how medical-device technological advances occur and should occur, we build on the successes of previous devices and move forward when it appears that there has been a meaningful technological advancement. If this technology is better, we should be able to demonstrate better patient outcomes or maintain good outcomes while saving money for the healthcare system.
I think the Titan device does both of those. It’s not just different for the sake of being different. Smooth titanium is not the same as Titan’s surface when viewed on a micron and sub-micron scale by the bone cells. The Titan technology is the only device that has a platform of cellular scientific data that shows robust bone formation in the cells and has a micron level and submicron-level technology. It’s not simply rough surface to the feel, but a roughened surface to the mesenchymal stem cell, 10-9 level. That’s where the cells see the Titan Spine technology.
I believe this technology is positioned to lead the way in spine surgery and to start thinking about the importance of surface technology. If I step back and give you a bit of landscape information: the dental industry has known about the importance of surface technology for quite some time. The dentists know that if they are going to put in a tooth implant they have to put a post in first and the bone has to grow into the post. They looked at biologics and BMP and they noted an uncontrolled lytic reaction in the jaw. They had a lot of bone resorption and they couldn’t control the reaction. So they turned to the implant surface, not BMP, to participate in the process of bone integration. They realized if they can get the implant to stimulate a physiologic response in the host bone, then it’s a controlled, natural response where the bone grows naturally into the titanium. This will result in a very stable construct.
Similarly, orthopedic total joint surgeons think this way. They want to know what the surface of their hip or their knee implant is going to do up against the host bone. They need bone in-growth. They’ve used things like cement in the past and had problems. They have used other biologics that they couldn’t control well. They’ve really spent a lot of scientific energy and a lot of thought on the surface technology of their implants.
Surface technology is a complete blind spot to most spine surgeons. It’s because spine surgeons have been brainwashed to think the implant doesn’t matter, or else we wouldn’t be putting plastic in between two bones and hoping it will fuse. But along with PEEK and plastic came BMP. And BMP is a very powerful, very strong bone-forming material. So you can use BMP with plastic and get a fusion. Unfortunately, the BMP also has potential for unpredictable bone reactions and it’s very expensive.
So, as spine surgeons are being weaned off BMP, we are becoming very concerned about the implant surface and implant materials. We now realize, like dentists and total joint surgeons, that we want the implant surface to be meaningfully engaged in the fusion process, and not interfere with it as PEEK may. Hence, the technological advances of a roughened titanium implant are starting to resonate with the spine surgeons as they start to become concerned about using PEEK without BMP.
Therefore, I believe the market is at a very important transition point where spine surgeons will start thinking more like total joint surgeons and dentists who already know they need to get the implant and the host bone engaged in a process that is predictable to form bone.
Q5: You mentioned the Endoskeleton device saves money; how does it achieve this?
If you look at cost savings on the front end, the retail cost of a large kit of BMP is roughly $5,000. With a Titan lumbar implant, I now use a biologic that goes for $1,900. That’s a huge savings which can be multiplied over hundreds of thousands of fusions across the country.
More significantly, on a macro-scale, if a spine surgeon has to revise a non-union, meaning a failed fusion, the estimated cost to the system, the insurance company, hospital, etc., is extraordinary. It’s probably over $100,000 for each non-union. That’s a huge hammer blow if you’re doing a bundled payment or an ACO model where they’re trying to control the cost of an episode of care. Revisions for failed fusions are extremely expensive and obviously have a negative impact on patients.
If you want perspective on the past, as it might relate to a future without easy access to BMP, ask surgeons how many non-unions they typically had to revise before BMP? Most would have a 25-30% non-union/ revision rate. Now, with BMP, non-unions have dropped substantially (to less than 10%) but no one wants to pay for BMP and/or they’re worried about the side effects. So if there is less utilization of BMP, the chance of failed fusions starts increasing unless you harness the implant to be part of the fusion stimulus. If the implant is engaged in the fusion formation, we can maintain good fusion rates and keep the non-union rates low. So far only the Titan Spine implants have the science that demonstrates this cellular bone healing engagement.
Q6: What is the typical learning curve for Titan’s Endoskeleton?
I think that’s one of the beauties of these implants: with all of Titan’s implants, there is essentially no learning curve for an experienced and trained spine surgeon. Hopefully we’ve all been trained to do a good job of preparing a disc space for a fusion.
The only caveat that I would offer is that many of us have been previously trained to aggressively remove the vertebral body endplates, shaving off bone in order to get to bleeding bone. That is not what we want to do when using the Titan implants. We want them to use good techniques, specifically clean all of the cartilage off the end plates, but preserve the bone. It’s called endplate-sparing preparation. That allows the implant to sit on strong bone. It just needs to be raw, exposed bone, and the implant can work directly on the bone. I think it’s somewhat confusing to the doctors – they think they need bleeding in order to get a fusion. Really what we need is good bone contact with the implant. If you nestle the implant up against the bone and remove the cartilage, the cellular process created by Titan’s Endoskeleton implant surface technology will take over.
Q7: Is there any reason that a doctor would not want to adopt something new like the Endoskeleton?
There are two main misconceptions that tend to be perpetuated about titanium that might make a spine surgeon initially hesitant. One myth is that it’s too stiff and it causes subsidence, and that PEEK is closer to the modulus of elasticity of the vertebral body. Some doctors will think they need to use PEEK in certain cases and titanium in other cases, but that has never made sense to me. Titan is currently conducting some mechanical testing that will hopefully dispel this myth.
The second misconception is that you can’t image around titanium meaning you can’t assess fusion on CT scanning because of scatter. One of the research projects we undertook here at the San Francisco Spine Institute was to look at the ability of radiologists to review fusions with the Titan Spine implant. We sent 38 CT scans to 2 independent radiologists that were not told about the other’s interpretations. We gave them a list of criteria, and they reviewed the scans and sent the data back to us. We had an independent person process the data.
The radiologists reported that there was minimal artifact from the titanium implant, meaning they could see around and within those implants clearly enough to determine if there was a fusion or not. Equally important, they agreed with each other on the majority of the variables. The inter-observer agreement was 88% across the whole study. They found very high fusion rates, minimal artifact, and they independently agreed on 88% of the over 300 data points they reviewed. We’ve submitted that for publication and I’ve also presented the data at a few major spine meetings. It’s been very well received because it has been a concern of doctors and surgeons to know if they can image around the Titan implant and determine if the fusion has actually occurred.
Speaking specifically to MRI compatibility, titanium is MRI compatible. Years ago there was a major shift in most orthopedic disciplines towards titanium for a couple of reasons: 1) it’s the most bio-compatible material. There are very few concerns as it pertains to patients’ bodies rejecting it versus stainless steel which was the previously popular material. And 2), titanium is MRI compatible and stainless steel causes tremendous artifact and obliterates some of the MRI capacity to visualize around it. All of us who have been using these implants for years have had to go back and do MRIs for one reason or another. The Endoskeleton is absolutely compatible with visualizing the neurologic structures immediately adjacent to the implant and above and below it as well. So, MRI compatibility is good and that is not a reason to worry about the implant in that environment.
Q8: What percentage of patients could benefit from the Endoskeleton?
Nearly all patients that need an interbody fusion could be implanted with the Endoskeleton.
Q9: Would you recommend the Endoskeleton to other surgeons?
Absolutely. It’s a workhorse in terms of its reliability and I’ve seen very predictable and reliable clinical outcomes. I have a very high comfort rate now on throttling back on my use of BMP. I was a very big BMP user at one time. It’s been maligned a bit, and somewhat unfairly in the press recently, but it has provided us a significantly increased fusion rate across the board. But it is expensive and there are concerns, both by physicians and patients, about the long-term effects of using something so powerful. So ideally we can step back a bit and use BMP on higher-risk patients, the ones that would present a very unusual or very challenging physiologic barrier to fusion, such as smokers, diabetics, and multi-levels. In the day-to-day surgeries in the cervical and lumbar spine that spine surgeons perform 70% of the time, I really don’t use BMP anymore.Download an Endoskeleton Fact Sheet and Discussion Guide (PDF)