You can't fight biology. In this clip from Thursday's all-new Grey's Anatomy, a patient begs for a chance to save his leg ... or a prosthetic that can do what his leg can.

After Alex helpfully tries to tell a dancer he can get by without his leg, the potential amputee responds with a stirring bit of showmanship to emphasize his own point.

He certainly makes a compelling case ... but will it help him? See below:

[video url="http://www.tvfanatic.com/videos/cant-fight-biology-sneak-preview/" title="Can't Fight Biology Sneak Preview"] [/video]

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.