Pods don't do knees anywhere. Knee is a surgical gold mine and ortho would never allow that (I certainly don't blame them). Also, knees would increase pod residency length, cause all kinds of unecessary conflict, and pretty much defeat the purpose of being a pod in the first place. We're foot and ankle experts... not entire leg. You certainly want to know the knee anatomy well since the joints all work like a chain biomechanical reaction, but a pod doing knees would be like having a hand surgeon do a rotator cuff... makes no sense when there are other guys who did different fellowships for that already.
Overall, 85% of foot surgery is done by pods. Pods do forefoot surgery virtually anywhere, and in some (well, actually most) states they do ankles if they have done the residency training for those certifications, it's in their state's scope, and they get hospital privelages for it. In the end, the rearfoot stuff is all fine and good, but pod started out as foot gurus and the best medical experts for those pathologies. If someone has a bad broken ankle, they just want it to work again. If they have a bunion, they want it perfect when it's done, and if they have a diabetic foot, they want you to save their foot as long as possible. The crazy trauma, pilon fractures, intermedullary nails, frames, etc generally hold a lot more interest for students and residents than they do for most practicing pods. It's good to know how to do all of that stuff and to have ex-fix, etc in your bag of tricks, but it's not really stuff the most pods do a whole lot of (there are cetainly exceptions such as residency directors, etc).