Lumbar Disc Replacements, the FDA , and A New Model of Lumbar Spine Motion
C Rosen, D Kiester
C Rosen, D Kiester. Lumbar Disc Replacements, the FDA , and A New Model of Lumbar Spine Motion. The Internet Journal of Minimally Invasive Spinal Technology. 2006 Volume 1 Number 1.
The Charité artificial disc replacement (ADR) was approved for use in the United States in October of 2004 by the FDA when Depuy Spine, the manufacturer, received their letter of conditional approval (1). Like all current models of lumbar disc replacements, the Charité was based on a faulty design that concluded the center of rotation of lumbar segmental motion was anterior to the spinal canal. As a result, numerous failures began quickly appearing and accumulating as time passed. The authors began seeing increasing numbers of patients who had both the Charité, as well as the Prodisc II, implanted with poor results and complications. These included not only various fractures and dislocations, but, most disturbingly, patients in severe pain without any obvious radiographic abnormalities.
The authors set out try to explain these events which had been either written off as surgeon error, "learning curve," or an unexplained event not related to device failure (2).
This lack of a logical solution was re-enforced with a financial disincentive to find one, given that the design had been accepted, applied, and marketed at great expense to both industry and investors. The authors compiled and analyzed complications presenting to their clinic. New understanding of unrecognized sources of pain from the replacements was validated both by diagnostic testing as well as direct surgical intervention. Ultimately, a new model of lumbar segmental motion was developed that not only explained the complications, but added insight into the mechanics of normal lumbar motion.