In January, she walked into the CEO job at Yahoo , unfazed by the company’s demoralized workforce, fractured management, and angry investors.

Seven month later, she’s taking flak for Yahoo’s new search partnership with Microsoft .

And did you hear that when she announced that deal–to secure a fighting chance in the lucrative search business against mighty Google –Bartz was recovering from knee-replacement surgery?

Well, you don’t know the half of it.

Bartz had the surgery with local anesthesia–an epidural to numb her lower body.

She watched the entire operation.

And she savored every gory minute of it.

Do normal people do this? “Normal people don’t do it,” Bartz admitted yesterday as she offered color commentary on the 47 minutes of cutting, hammering, and retrofitting an artificial left knee where her 60-year-old real one used to be.

Bartz, bear in mind, has never been normal when it comes to her own health issues. At 43, when she joined Autodesk as CEO, she was diagnosed with breast cancer that very week. She worked through months of chemotherapy, taking off one month to have surgery.

“I watched them saw my leg in half,” Bartz said about this latest medical adventure, enthusiastically detailing the skin, fat, cartilage and bone that she viewed on a video monitor perched beside her head on the operating table. “I asked, ‘Where’s the blood?'” To her surprise, there was hardly any. Thanks goes to a hefty tourniquet that her surgeon, Dr. John Dearborn at Washington Hospital in Fremont, California, used to keep the operation not too messy.

Bartz is spending this week in Hawaii, on vacation and recovering from the July 8 surgery, as well as from the eviscerating reaction to the Microsoft partnership, which was announced July 29. (Yahoo stock has dropped from $17 to below $15 since then.)

“You have to go back to the center–why it was important,” she says about the deal and Wall Street’s displeasure. “It’s important for the long-term health of Yahoo. It’s important to grow audience.” Essentially, she’s slicing off a piece of Yahoo, search technology and engineering, and giving it to Microsoft so that Yahoo can focus on selling on-line advertising and developing on-line content.

As for her own surgical procedure, Bartz says that Dr. Dearborn did six other knees the same day he did hers. She was his only patient, she boasts, who went straight from bed to walking with a cane–no walker. “And I was off the cane in a day and a half,” she adds.

The pain is not getting better each day. “It swells up like a balloon,” Yahoo’s boss says about her new joint. That’s when it really hurts. But she’s bearing it. Now, she notes, she has one fake left knee and one fake “left boob. That’s the bionic side of me.”

Bartz, by the way, did not grant an interview, per se, to talk about her surgical ordeal. I was speaking with her about this year’s Fortune Most Powerful Women issue (which will be out in mid-September) and simply asked how she was feeling. The conversation proceeded. At the end when I asked if I could share details of her surgery, Bartz said, “Sure, as long as you pass on two pieces of advice.”

“Stop jogging,” she said. “And stop playing singles tennis.”

Yahoo’s never-say-die chief executive pushed herself too far for too long, with bad body parts. Once she recovers from this, will she go back to running or tennis? “No, I’m down to one sport,” Bartz says. “Golf.”