How does podiatry make a 3 year surgical residency work? Even optho is 4 without fellowship and ortho is 5. What exactly is the surgical scope?
"Surgical residency" is a commonly used, but misleading term. It's really a podiatric medicine and surgery residency (PMSR). And like any other doctor, podiatrists work well outside of their scope during residency. For all that, three years isn't too long at all, but it's probably just about right. A handful of programs have even started 4 year residency positions, but 3 year positions are still the overwhelming majority.
The residency includes rotations through anesthesiology, dermatology, emergency department, internal medicine, infectious disease, orthopedics, pathology/lab, pediatrics, radiology, rehabilitation, rheumatology, general surgery, trauma, vascular surgery. Of course the specifics of these rotations depends on the hospital, but most residencies include all but a few of these rotations and some include additional rotations (like psychiatry).
Then of course there are all of the foot and ankle cases done through podiatry, orthopedics, or whatever various other departments (surgical and nonsurgical).
In regards to surgical scope of practice, that depends on the state. There are still a few states in which podiatrists can only operate on the foot, below the ankle. In most states they can operate up to and around the ankle. Many states also include the leg (below the knee) in their surgical scope. And in a few states you can technically do some procedures on soft tissues of the thigh, but I think they mostly just use this for autografts or to treat varicose veins. The actual surgery could be on bone, on blood vessels, on nerves, on muscles, on tendons, on ligaments, etc. It's a regional specialty, not a system based specialty, so literally any piece of tissue below the knee (or ankle) is fair game—including amputations of toes or parts of the foot.
For medical scope it's mostly limited to treating local pathologies and local manifestations of systemic pathologies—a lot of conservative orthopedic stuff and a lot of lower extremity dermatology. Of course in many cases treatment may involve prescribing medications that have systemic effects (pain meds, gout medication, etc), but as long as the primary pathology is within the foot or leg then it's all good.