Conversation so far:
Where was Mickey Mantle born?
Mantle was born on October 20, 1931, in Spavinaw, Oklahoma.
What did Mickey Mantle's parents do?
His father worked in lead and zinc mines.
Where did Mickey Mantle go to school?
Mantle was an all-around athlete at Commerce High School.
Did Mickey Mantle go to college?
Oklahoma offered him a football scholarship.
What was Mickey Mantle's major in college?
Are there any other interesting aspects about the Mickey Mantle article?
In his sophomore year, he was kicked on the left shin during a practice game, and he developed osteomyelitis.
Did osteomyelitis stop Mickey Mantle from playing ever?
He was treated at the children's hospital with the newly available penicillin, which reduced the infection and saved his leg from amputation.

Question: When did he decide to stop playing football?
Self-contained rewrite: When did Mickey Mantle decide to stop playing football?