Wiktionary
dead leg
n. (sport) an injury caused when a player receives a hard knock on the upper thigh, crushing the muscle against the bone.
Usage examples of "dead leg".
The parasail streamers must have caught firmly in the upper branches, and some of the shroud lines bore my weight as I scrabbled with my left foot on slick fiberglass to pull my dead leg from the wreckage.
I've tried promiscuity and I've tried true love, and they're like my dead leg: they don't work.
The rest had restored the feeling in his dead leg, and he knew the seriousness of the wound.