Prosthetic leg
From Tardis Wiki, the free Doctor Who reference
A prosthetic leg was a type of artificial robot type device that were used in place of real limbs. After Ram Singh had one of his legs severed by Corakinus, he was given a prosthetic one by the Twelfth Doctor (TV: For Tonight We Might Die). Ram struggled to walk on it as first, but was soon able to teach the leg to act like his own and was even able to play football again. (TV: The Coach with the Dragon Tattoo, Nightvisiting)