Wifey had similar modifications & she's still flexible (That didn't sound quite right but I'll leave it alone).

In theory, the fusion will cause increased wear on the ajacent disks over time but the few people I know that have had the procedure have not had any significant degeneration & the the benefits have been well worth the effort.

For me the biggest concern is toxidity or rejection of the foreign materials. Some small percentage of people do experience those problems. One of our own members has gone through that after a severe car accident.