It is possible for people to develop a stress fracture in the metatarsal bones with no specific injury. This is often due to increased activity such as training for a long run. It can also be due to other issues such as foot shape. The important thing here is to diagnose the problem
Treatment usually consists of rest, ice and elevation of the foot. It is very uncommon that surgery is needed for this problem. See here for further info: http://orthoinfo.aaos.org/topic.cfm?topic=a00379
All surgical procedures carry some risk. These risks are usually rare, but can include infection, bleeding, damage to surrounding structures such as tendons or nerves, numbness, dysfunction of foot, ongoing pain, unsightly scar, painful scar, wound healing problems, swelling. There is also a risk that the procedure does not work fully and that the patient is left with some ongoing symptoms.
There are also some medical risks to surgery such as a clot in the leg (DVT), clot in the lung (pulmonary embolus or PE). The general anaesthetic has rare risks of problems such as heart attack, stroke, chest infection and in extremely rare circumstances, death.