Tiger Woods is the host of the AT&T National this week. But he won't be there. Flying, he said during a teleconference Monday, causes his rebuilt left knee to swell too much.

Woods was cautious in his comments about when he might be able to start playing golf again following reconstructive knee surgery. Recovery times are different, he pointed out: could be six months, could be nine months, could be a year. Wait and see.

He did make a few comments about what specifically was done during the surgery to repair a ruptured ACL:

Woods underwent an anterior cruciate ligament (ACL) reconstruction of his left knee.

“They did take a graft, basically a tendon out of my right hamstring, and implemented it into my left knee and made it my new ACL and they fixed a little bit of cartilage damage I had in there, and that was about it,” he said.

He also talked about his attempt to rest and rehabilitate at the end of last year after rupturing the ACL following the British Open, and what happened throughout this season that finally required the drastic surgery:

“The reason why I took the long layoff is to develop my hamstring and my glute and my calf…to basically give my leg more stability,” said Woods, who tore his knee ligament after the 2007 British Open while running and took 10 weeks off at the end of the season.

“People have played without ACLs and have been very successful. Downhill skiers ski without ACL’s, but they’ve got extreme sized glutes and hamstrings, and that’s their checking mechanism. And I tried to do the same thing.

“I went through the rehab process and tried to get it ready for this year. It held up great,” said Woods, who won his first three events in 2008 and was Masters runner-up before claiming his 14th major at the U.S. Open.

“Unfortunately, as I kept playing on it, it became more unstable,” he said. “The natural rotation of the golf swing without the ACL made it a little bit unstable, and it caused some cartilage damage because of that. I had that rectified after the Masters.”