Re: 25 year old needing l4/l5 disc replacement
I'm a little older than you, had an annular tear with an extruded disc causing mild/moderate central canal stenosis and bilateral foraminal stenosis (no known injury, just woke up that way), at L4-L5. I talked to my very expensive, very congenial orthopedic spinal surgeon who has a flock of fellows following him around, and he advised against an artificial disc replacement for my situation. The short-term results for a one-level ADR have been promising but statistically, he thought not much better than fusion and he indicated there are no long-term studies (at least in the US) for the outcome of artificial discs. You might also consider the risk of needing corrective surgery in the future to fix a failed ADR, but not having the means to pay for it, if your future health insurance does not cover it as a pre-existing condition.
You shared some of your treatments, but you did not mention what your back injury is, except that it is at L4-L5. I realize that your choice of doctor is limited, but did the doctor discuss any other options? Make sure you have a good advocate in your corner, because it sounds like you need one, especially with the insurance company sending you denials.