Tommy John surgery possible for Adam Wainwright: What it is, and who's had it (PICTURES)

(CBS/AP) Will St. Louis Cardinals ace Adam Wainwright need Tommy John surgery? The team fears he will, but he's getting a second opinion.

SLIDESHOW: Tommy John surgery - who's had it? 

Team spokesman Brian Bartow said Wednesday night that results of MRIs and other tests were being evaluated. The team anticipated a news conference Thursday afternoon to disclose findings.

The surgery is named after left-handed pitcher Tommy John, who in 1974 became the first pro athlete to successfully undergo it. It uses tendons from elsewhere in the body to repair damage to the ulnar collateral (elbow) ligament. It can save careers but would be a season-ender for Wainwright.

Wainwright, 29, began feeling soreness Monday. Trainers examined him Tuesday and he flew back to St. Louis on Wednesday for tests and consultation with team physician George Paletta. Earlier in the day, general manager John Mozeliak said "things do not look encouraging" for the right-hander, who injured his elbow while throwing batting practice Monday.