Most of you would agree that key features in a disc design is the center of rotation, the stability of the product and the material used. We're just beginning to capture the retrospective data in a manner that provides surgeons with the clarity necessary to make these procedures successful. Over the years we have been introduced to metal-on-metal, ceramic-on-ceramic, metal-on-poly, poly-on-poly, and ceramic-on-poly. Legitimate arguments can be made as to the pro's and con's of each design.
So the question must be asked of our readers, what is the optimal design? In terms of motion, cervical discs can be classified as unconstrained, constrained, semi-constrained, and disc that mimic movement. Yet, questions still remain as to the effect this procedure has on disc height and facet joints. Time and retrospective data is providing the industry with a better understanding of how altering the natural biomechanics of the spine can result in success and or failures of these procedures. As much as we have learned in the 45 years since the first disc was created and implanted, there is still work to be done.
Unconstrained devices allow for translation which theoretically mimics normal motion, yet may increase shear and torsional loads on the facets. In addition, a greater emphasis is placed on surround soft tissues and the PLL for stability. Constrained devices are known to minimize loads through the facets but have a fixed axis and required accurate placement. How many of our bloggers marvel at the claims that many of the players in this arena have made regarding their devices. Some have called it first gen, some called it second gen, some claimed in was third gen, all without any long-term retrospective data. The industry was bombarded with marketing at its best, or its worst.
We have been told that some materials provide better wear resistance (ceramics), some have a higher wear rate but low stiffness (polymers), we've been exposed to keels, teeth, and coatings, yet, the critical feature is the device's axis of rotation and whether it matches the physiological center of rotation. The challenge is identifying the center of rotation on a level by level basis. So who has the optimal design?
Is it the Synthes ProDisc C, is it LDR's Mobi-C, is it Spinal Motion's Kineflex-C, is it Globus' Secure-C, is it Stykers metal-on-metal CerviCore-C, is it NuVa's CerPass, is it Medtronic's Prestige, these are just a few of the prominent players in the market, in addition how big will this market truly be? When one analyzes the analysts forecasts, one can only shake one's head in amazement. Some have estimated that this will be a $400-$500 million dollar, but those people are smoking something that many of us have never smoked, or at least you didn't inhale. Contrary to popular opinion, TSB sees this at max as a $200 million dollar marketplace, as long as the insurance industry and the government don't "fubar" this procedure. In addition, this is a young person's procedure, (sorry grandma), especially at these prices. So in the spirit of debate, who has the best design, how big will this market truly be, and is this a procedure for one or for all? TSB wants to know what our bloggers think?