[annapurna]

The discussion about the M6 was on this site but it seems like the search function on the site rejects M6 as a search phrase so I don't know that it'll help you. Rich AKA Harrison might be able to assist if you contact him. Otherwise, there was some a lot of discussion along with anecdotal 2nd hand information from a patient who was operated on by Bertagnoli at ProSpine.

I have not kept up with the new ADR models. As I said, up to ten years ago, there never seemed to be convincing evidence that the different models actually gave different levels of performance. That said, the engineer in me says to go for simple, well tested, styles of design. The more complex designs may perform better in the lab but increase the number of failure points in the field. BTW, the M6L is a complex design due to the mesh, pair of adhesive bonds holding it together, and behavior of the elastomer material. Complexity here is defined by the number of parts which must all work correctly to achieve a functional device, not by the elegance of the design.