Most amputees died from infection. Of those who survived higher status pirates would mostly use crutch or cane like devices, but would occasionally receive primitive versions of what we would consider prosthetics. The most likely scenario was that the average unprivileged legless pirate would remain relatively immobile below decks and be used for sexual satisfaction of the rest of the crew.

-Botting, Douglas. The Pirates (The Seafarers; v. 1). Alexandria, Virginia: Time-Life Books, 1978.

-Seitz, Don Carlos, Howard F. Gospel and Stephen Wood. Under the Black Flag: Exploits of the Most Notorious Pirates. Mineola, New York: Courier Dover Publications, 2002