Joe Montana on Friday shrugged off his back surgeon's statement that the San Francisco 49ers' quarterback's advancing arthritis makes a career-ending injury increasingly possible.

Montana said he believes there's no more risk of being injured while playing than there was when doctors cleared him to return after removing a ruptured disk in September 1986.He said the surgeon, Arthur White, warned him after the operation that another one would be likely at some point in the future.

"But there's no specific date - it could be 20 years from now," Montana said at the team's training facility. "I'm pushing the future as far as I can."

Montana, 32, said he hopes to finish out his contract, which runs another four seasons.

In November, nearing the end of the fifth year of a six-year contract, he signed a three-year extension through 1992. He could earn nearly $10 million in the five years for which he's still under contract, making him one of the highest-paid athletes in sports.

White said Thursday that it's "amazing" that Montana is still playing 21/2 years after the operation. He said the quarterback is "eating up the years really fast."

"It would not surprise me, after he played another season or two, that he would need additional surgery and would have to finish playing," White told The Tribune of Oakland.

At a news conference Friday, White said he was not misquoted in the newspaper but said the tone of the article was wrong.

"I go along with (Montana) that his body will tell him when he should stop and he will tell me when he has symptoms," said White, who noted that CAT scans and X-rays can help experts predict Montana's condition.

"But the major thing is his pain," said White, adding that Montana should be able to play for several more years.

He said Thursday that the opening in Montana's spine in the small of his back where the disk was removed is closing because of the rigors of football.

"As the hole closes off, the likelihood increases more and more that any single blow could close it off, and that would be it," he said.

But White, who said two years ago that he thought Montana was "crazy" to continue playing, emphasized that Montana is in no more danger of paralysis or other catastrophic injury than any other football player.

"It's not as if he's throwing all caution to the wind," he said. "Besides, if a million dollars was on the line, I'd probably play the next game, too."

Montana said he has a CAT scan done every year to monitor his back and talks with White about every other month. The likelihood of another operation, according to Montana, "has always been a topic."

"One of the things he told me is that 70 percent of all back patients who have had operations usually require them again," he said.

Montana believes the doctors are overly skittish because they're dealing with a football player.

"I think that, because of the type of game it is, the physical part of it, they're not used to dealing with patients who are involved in this type of activity," he said. "I think they're sort of learning things as I go along."

Meanwhile, the 49ers went through their heaviest practice of the week Friday in full pads. They will have a light workout on Saturday and leave at noon Sunday on a charter flight for Miami.

"We had a good, sharp practice," said Coach Bill Walsh. "We're healthier every day. I don't see any real (injury) problems."

He said cornerback Eric Wright, recovering from a lingering groin injury, appears to be ready to play in the Super Bowl.

Walsh refused to comment on the issue involving Montana's surgeon.

Montana's frustrated backup, Steve Young, took some snaps but said he can't argue with his No. 2 role in light of Montana's "inspirational" performance in last Sunday's 28-3 NFC championship game victory over Chicago.

"I would be lying if I didn't tell you that backing up is basically driving me crazy, driving me nuts," Young said. "I don't think I can get too much better by watching.

"But I'm realistic," he said, "and I love being with the 49ers. We're in the Super Bowl and no one will be happier than me if we win. We'll work out the rest later."