If he cannot, surgery is the next option.
"We're not terribly optimistic, but there is still the possibility he can come back and throw, and throw with a minimal amount of discomfort," Phillies general manager Ruben Amaro Jr. said Tuesday at Bright House Field. "It got worse the last time [he tried to pitch through it], so the probability of that happening again is probably pretty high, but we don't know that, and we probably won't know it until he starts to throw and goes through his progressions."
Lee has attempted to rehab twice from the injury. He tried unsuccessfully last summer and again in the winter.
"It's not a good sign, obviously," Lee said. "It's not good."
Lee pitched two innings Thursday against the Astros in Kissimmee, Fla., and said afterward he felt normal. But the following day, he felt a return of the discomfort he initially experienced last season.
Simply put, the discomfort has not gone away with rehab.
Recovery from surgery would take six to eight months, which Lee acknowledged could end his career. Lee is in the final year of his five-year, $120 million contract. He has a $12.5 million buyout on a $27.5 million club option for 2016, but Lee has hinted in the past that he might not pitch beyond this deal.
"I've got a family at home, and I've been away from them for a long time, so that is part of the equation," Lee said. "If I were to have the surgery, am I going to go through all that to try to pitch again, or am I going to shut it down? That's a decision that I'll have to make once that time comes, if that times comes."
It might not take long to see if Lee can minimize the pain.
"It may take a couple of days," Amaro said. "If he feels discomfort, then he might have to shut it down. He threw today and felt OK. Really didn't feel anything different. It's a very, very mild sensation he's got in there."
"There's no timeline," Lee said. "I'm just going to keep doing what I've been doing and do it as long as I can. I'm not going to go out there in pain to where something bad can potentially happen. That doesn't make sense to me. So I'm going to play as long as I comfortably can. When it's uncomfortable to play and it hurts to play, then it's not worth it."
Lee said he is comfortable with his baseball career if he cannot pitch again.
"It's not just results," he said. "I feel like I've done everything I could in my career to give myself the best chance. If it happens to be nearing the end, it is what it is. I don't have any regrets. So that's the main thing. Just as long as I can look back and comfortably say, 'I didn't cheat this or cheat that. I wish I would have done this or would have done that.' As long as I don't do that, I can live with anything."
The Phillies also announced that catcher John Hester, who is a non-roster invitee, had surgery to repair a complex tear of the medial meniscus in his left knee. He will take at least six weeks to recover from the surgery.
Third baseman Maikel Franco was also not at Tuesday's game because of a root canal.