There's still no official word on how long Britney Spears will be sidelined because of the knee injury she suffered Tuesday, but an expert on knee surgery said Spears would do well to give her joint a rest for several weeks.

According to Dr. Eli Bryk, chairman of orthopedic surgery at St. Vincent's Hospital in New York, the best-case scenario is that Spears would only need two to three weeks after surgery -- which took place late Tuesday night -- before she can dance again. In the worst-case scenario she'd need six weeks.

Spears is scheduled to resume her North American tour on June 22 (see [article id="1488285"]"Britney Busts Knee, Complicating Video Shoot And Tour"[/article]).

"It's highly unlikely that in 11 or 12 days she'd be able to resume dancing," Bryk said. "At least, not the kind of athletic dancing she does."

Click for photos of Britney's fall

The procedure is usually performed as elective surgery on an outpatient basis and is rarely considered a major operation. There are a number of different types of arthroscopic surgeries to correct floating cartilage, depending on whether doctors decide to remove or repair the problem, Bryk said.

"In her case, it was an acute onset and obviously very painful," Bryk said, "so she probably has swelling and pain and may have had locking in the knee joint. She probably couldn't extend her knee, probably couldn't walk."

Bryk said that her doctors should advise her to keep weight off the knee, even if she's able to walk. Prescription painkillers and physical therapy would also be in order. If Spears tries to dance, he would recommend that she ice her knee before and after -- just like athletes who've been injured.

"The muscles become very weak after this surgery," he said. "The knee joint becomes very stiff. She might need a brace or some extra support. She can't return to full activity, so she may have to revise [her stage show] accordingly. This is not going to go away rapidly."