Speaking out for the first time since learning he needed further knee surgery, Antonio McDyess told The Post yesterday he was “devastated” by the news and admitted to being “worried” about his future. However, McDyess said he won’t think about retirement – unless he can’t play the 2003-2004 season.

Yesterday morning, McDyess’ mood brightened. At the Mayo Clinic in Rochester, Minn., he was shown X-ray images of his left patella bone in the wake of Tuesday’s two-hour bone-graft operation.

“The X-rays were unbelievable,” McDyess said in a phone conversation from his hospital bed before he was discharged in the late afternoon. “You couldn’t see no line in the bone. All I could do was smile. I was definitely satisfied. I was able to put a smile on my face.”

Knicks fans haven’t been smiling since last week’s revelation that he would need a third operation in 18 months because the patella (kneecap) hadn’t fully healed.

“All I can say is I’m more disappointed than them,” McDyess said. “It was devastating. I can’t explain how I felt – shocking more than anything. I thought I was getting ready to play.”

The Knicks have set no timetable for his return, which means he could miss the start of next season if the healing isn’t swift. Rehab begins in two weeks, and he’ll be on crutches for an indefinite period.

“Of course I’m going to be worried,” McDyess said when asked if he’s concerned if he’ll ever make it back for a full season. “As a player, after a third surgery, you wonder if things will be the same, wonder how my knees are going to respond when I get back on the court.”

Asked if he’s certain he’ll make it back next season, McDyess said, “That’s what they tell me. I can only go by what the doctors tell me. I’ve got my fingers crossed. Hopefully I’ll be back and be as strong as I was.”

McDyess said he’s still groggy from pain medication, but agreed to talk, despite being asked if he would rather speak another day.

Full healing from a bone-graft procedure could take anywhere from three to six months, putting October training camp in jeopardy.

“That’s my goal,” McDyess said. “Will it happen? I don’t know. They didn’t give me a timetable, but they said I will play next year.”

Retirement thoughts floated in McDyess’ head last October after he fractured his kneecap – his second major knee injury in a 12-month span. But now he’s not thinking about quitting, with one year left on his contract worth $13.5 million.

“If I was unable to play next year, I would think of [retiring],” said McDyess, who turns 29 on Sept. 7.