[The interspinous U implant (now Coflex): long-term outcome, study overview and differential indication].

The safety and effectiveness of the Coflex implant has been confirmed in a large retrospective data analysis. Further studies investigated the long-term clinical outcome up to 12 years and evaluated all associated complications showing a strong safety record. Prospective studies oversee only a small patient population at this point and exhibit scientific shortcomings. A large prospective, randomized, concurrently controlled multicenter trial is underway collecting data in seven spine centers in Germany. A similar study is being performed in the USA with a different control group regulated by the Food and Drug Administration (FDA). A differential indication is the stabilization of an adjacent segment next (above) to a fusion. Stabilization of a functional spinal unit after nucleotomy is not promoted by the author.