Agreed. There is lots of incentive to do just that , why pay a doctor 500 bucks to do it? A sawsall works great but you have to have the right blunt ended blade with some duck tape on the end and insert it under the cast with the cutting teeth up, and operate it on low sweep. Once you get the first inch or so the rest is easy as long as the entire limb is solidly imobilized.
Or you can use a 10” circular saw and zip through it in 2 or seconds.
Or you can use a 10” circular saw and zip through it in 2 or 3 seconds.