The game was held up for six minutes as a motionless Wrack was carried from the field.
Boss Paul Merson said: "I didn't have any serious injuries in my playing career but I feel really sorry for the lad.
"It was one of those things, it was a pure accident."
The tackle resulted in a penalty, which England Under-19 striker Matty Fryatt converted to give the Saddlers the lead.
But Yeovil fought back to win thanks to strikes from Phil Jevons and Kevin Gall.