Dr. Robert Thompson performed the procedure in St. Louis, manager Terry Collins said.
Thompson had planned to remove Harvey's top rib, with the goal of relaxing muscles that were constricting a nerve bridging the neck and shoulder. The nerve compression caused weakness in Harvey's pitching arm and a loss of feeling in his fingers.
Agent Scott Boras has estimated a six-month recovery time for Harvey, which would leave him ample time to be ready for the 2017 season.
Harvey went 4-10 with a 4.86 ERA in 17 starts before getting shut down.