Jones fractures are located in an area of the bone that has relatively poor blood supply, and there are two major tendons (the peroneus tertius and peroneus brevis) that attach to the bone in that region.  With their constant pulling on the bone and the pressures on the bone caused from weight-bearing, these fractures are notorious for healing very slowly (a delayed union) or not at all (a non-union). 

Normal treatment includes non-weight bearing and immobilization with a cast, but often surgery is required to put in some sort of hardware to hold the bones together.  K-wires, screws, plates or external fixation are frequent forms of fixation.