Conversation so far:
what did Charles Haley do with the cowboys?
moved to right defensive end.
was he succesful?
received the UPI NFC Defensive Player of the Year Award.
did they win the super bowl?
He started in Super Bowl XXX.
when dd=id he retire?
He retired after the season, because of his back injuries and his youngest daughter Brianna having been diagnosed with leukemia.

Question: what injures did he have?
Self-contained rewrite: What injuries did Charles Haley have?