Everyone is different so I'm told from my Dr. I had surgery to remove large bone spurs from my neck that prevented me from swallowing and eventually obstructing my airway. They grew back to the point of having issues again in 18 months. I have had vertebra fusing together also in this short amount of time. I have read about people who have had it for 25 years on this forum so i think there is a lot of difference in people's progression rates.