The paragraph between those two clarifies that "prosthetic devices" can include things like orthopaedic shoes. I'd assume that if someone does get, say, a leg amputated, then they're in a wheelchair for a while and maybe have a brace on their other leg to help it handle being used more heavily while the patient gets used to using a prosthetic leg. That's your three prosthetic devices there, even though there is only one limb amputated.

As for the 90% thing, though, I fully expect that that's Shoigu lying. It's Shoigu, after all