I have had Four opinions, Two of them are disabled by the FDA.
What I mean, is that the USA will not allow ADR, Yet, one surgeon, stated that they were seeing more artificial discs fail, I wonder what these types are?
People are having a lot of issues with the ball and socket type, they move 'too much' and not natural like the M6.
The movement puts too much motion on the facet joints.
My initial evaluation with Bierstedt, was the L45-L51, M6, but I have had a discectomy/Laminectomy/foramen at the L2-3 level. This looks good on the MRI, 10 months later, but can cause pain, and still get shooting pain, (that lateral femoral is gone/damaged severly) down the leg.
Not really crazy about getting cut open, and I would require two incisions, but you have think, if they go in the first time, you really want two things settled.
One, they take care of ALL issues the first time, and Two, you have the best outcome.
If the Dr can lift this L5-S1, then go for it, you will have the disc height and movement.
The M6 comes in different sizes, the endplates, and the plates have keels to grab the bone, to stabilize, they are coated, so ossification (bone growth on the endplates) takes place, also, the endplates have different (lorthotic) angles for aligning the ADR.
M6-L Artificial Lumbar Disc | Spinal Kinetics
Here are a few pictures at the L5-S1 level.
It is a hard decision, of this, there is NO confusion there.