Becker's Spine Review

57 Executive Briefing: on the edge of the implant where there is significant endplate to implant contact. This is similar to what is seen on proximally-coated total hip implants in general ortho- pedics. KH: In my practice, on a daily basis, I see patients that I have fused using titanium cages with a subtractive surface technology, and the patients do better quicker. This is anecdotal in my practice, but many studies have now been completed, and many more underway, that confirm my clinical practice experience. Q: What benefits have your patients experienced? DD: Lower cost of care. Improved early postop outcomes and accelerated return to activity with higher fusion rates. DB: It's my impression that my patients experience higher fusion rates using this implant with earlier clinical results. It's been a win-win. They feel better sooner and heal more thoroughly with a lower risk of complications. These days you also have to look at the value proposition, and this is affordable technology for the type of procedure we're doing. RR: You can see the implant very conclusively during intraoperative X-rays and you can place the implant more accurately. You can have a better designed implant with more structural integrity so you're able to do more with it. I think in the future, there will be more sophisticated implants fabricated in more anatomically correct ways or extension capabilities for a natural interbody fit. The benefit would be to promote arthrodesis and promote it in a way that we have a higher percentage of success in the material use. Q: Why do you think there is a growing trend away from PEEK and toward titanium? KH: PEEK is an antiquated technology that was probably sufficient when we used large doses of BMP, although that combination had a high subsidence rate. As surgeons moved away from BMP, fusion rates decreased, and the choice of implant became a priority. Now, the surgical community is beginning to understand PEEK is suboptimal for bone growth and fusion. We were taught the modulus of elasticity was better in PEEK, which is a marketing ploy not based in science. The design of the implant, surgical technique, and place- ment of the implant on more structurally-sound areas of the endplate need more consideration from surgeons than the modulus of elasticity. AB: Many trends are driven by marketing and industry, but I think this is a case where science is driving the trend. PEEK was clearly driven by industry and was sold as a way to better match the stiffness and modulus of elasticity of bone to prevent stress shielding and subsidence. In reality, PEEK still showed subsidence and the subsidence rate of titanium was related to implant design, location of implant placement, and surgical technique. A side benefit of PEEK was the ability to see fusion through the cage and limit scatter seen in older MRI and CT scans. The growing scientific evidence showing the downsides of PEEK combined with the upregulation of osseous integration seen in titanium is driving the trends today. Q: But didn't the industry primarily move away from titanium implants in the late 1990's? How are the new titanium designs different? KH: Titanium implants have changed dramatically in the past 20 years. Earlier designs, such as threaded cages, were subject to subsidence because of their design limitations. They would violate the endplates, usually be placed centrally in the vertebral body on the weakest structural area, and had relatively small footprints. Imaging of the neural structures around these dense implants was difficult, with the design of the implant and the poor quality of MRI and CT technology at that time. Now, new designs, spearheaded by Titan, are very easy to image around. The comparison of earlier titanium implants to those manufactured by Titan is like apples to oranges. New cages have better designs, use far less titanium, so they are less dense and easier to image, spare the endplates, and are placed on better load bearing surfaces of the endplates. Also, Titan has the only true nanotechnology implant that has been proven to interact with osteoblasts and stimulate them to form bone. Again, MRI and CT scan technology has dramatically improved to allow better imaging with less scatter. Q: There also appears to be a trend to coat PEEK implants with titanium, which appears to combine the best of both materials: the osteogenic benefits of titanium with the radiolucency and modulus of elasticity of PEEK. How do you view these types of implants? DD: I think the new composite devices are an admission of the failure of PEEK. The high rates of fusion and low subsidence rates with new titanium implant designs clearly debunks the myths put forth regarding the modulus of elasticity and the fact that PEEK cages are now being coated with titanium is an admission of the value of implant surface. The reality is that the coated surfaces are creating more potential problems with delimitation of the surface and third body wear debris. The titanium coatings that are being applied have not even been studied in term of a cellular response. The data in the literature on roughened titanium surfaces and cellular responses to it are almost entirely based on a proprietary surface which is different than the surface coating being applied to PEEK. Touting that an unstudied surface application has the same osteogenic properties Executive Roundtable: Surface Technology

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