I am currently using an external bone growth stimulator by Orthofix, via the recommendation from my surgeon. Given my genetically bad spine, coupled with 35 years of RA, I opted to try it. I have a much higher risk of fusion failure (4 level ACDF) and will try anything to keep failure from happening! My PEMF collar is worn 4 hrs/day for at least 6 mos post surgery. They do make a brace for the back, as well. I can’t comment on it’s effectiveness, but it comes with good success stats.