The prognosis for Jason Smith: A postsurgery night in the hospital, then who knows how many nights before he resumes playing for the 76ers.

Smith, the second-year big man, had successful reconstructive surgery on his left knee yesterday. The procedure was performed by Dr. David Altcheck at the Hospital For Special Surgery in New York. Dr. Jack McPhilemy, the Sixers' orthopedic specialist, observed the procedure.

Smith suffered a torn anterior-cruciate ligament Aug. 6 at an NBA-sanctioned camp in Las Vegas directed by longtime coach Tim Grgurich.

The Sixers have not publicly set a timetable for Smith's return, but he will likely miss the coming season.

"We're not thinking that way," said Mark Bartelstein, Smith's agent. "That's not the plan. We just want whatever is in Jason's best interests.

"It would be good to have him ready for next summer, but that's too far down the road. No one's worrying about that now. What's important is to get him ready to come back."

Smith, from Colorado State, averaged 4.5 points and 3.5 rebounds in 14.5 minutes last season, then averaged 3.3 points and 2.5 rebounds in 13.7 minutes in six playoff appearances. By all accounts, he showed more aggression and better strength in five games in the Las Vegas Summer League. *