[mmglobal]

I don't think you are being difficult, Rob. These are tough questions and unfortunately, when you decide what to do, you still won't have all the answers as they don't exist yet.

Yes, with the Bryan disc, there is much more milling and the process is complicated and difficult. They must mill a negative in the bone that provides a 'cup' that the prosthesis fits into. Imagine the jig that is used to mill into both the superior and inferior endplates. Too many steps... to easy to get it wrong. I don't have the Bryan data at my fingertips and am relying on memory and impressions made when I attended the sessions where Bryan experience was presented.

For me, this really highlights the problem with the data and with this whole process. There is no question in my mind that there is a huge disconnect between the data and the experience. Especially with an extra-difficult surgery, there will be a greater disparity between the more skilled and experienced surgeons and the ones that are less so. I know several top surgeons that have done many Bryan procedures, but all of them stopped using Bryan when newer designs became available. They all talk about HO rates and the difficulty of the surgery. However, when I see Bryan data presented at the conferences, it looks much the same as for the other cervical discs. (And for the lumbar discs, and for fusion, and for.....) Maybe they all use the same computer program and it's stuck... only outputting 85% success rate, regardless of the input.

Regarding avoiding HO... I believe that it comes along with doing excellent carpentry. It comes with experience. There is a trade-off at many places in the surgery. Unless you have totally regular shaped end plates, some remodeling will be in order. How much? Too much or inappropriate remodeling and you increase the risk of HO, subsidence, migration. Too little remodeling and you don't have a good platform for the prosthesis, increasing the risk of migration, toggling (motion of the prosthesis), or ??? Use of bone wax may reduce the risk of HO, but inappropriate use of bone wax will come along with an entirely new set of risks. Again... experience, care, skilled surgeon are paramount.

Regarding Sahauro's question about theoretical vs. numbers... I don't know. My impression is that they abandoned Bryan because there was something that was much better... not because of HO rates. If there was only a choice between Bryan and fusion, I suspect that they would still be doing Bryan procedures where ADR is indicated and that, as with other surgeries, better surgeons will have better success.

Mark