I fractured my sesamoid as well–into 3 pieces in fact. I wore a walking boot for 8 weeks and then spent another 2-4 weeks doing marches, medball throws, and lower body weights. In combination with a bone stimulator, I made a full recovery and ran PRs just a couple months removed from taking the boot off. It still got some irritation in the next year after the boot coming off and I occasionally get it now, but overall, it recovered surprisingly well.