Brian Giles Undergoes Microfracture Surgery

The San Diego Union-Tribune reports Padres right fielder underwent microfracture knee surgery on Thursday to repair an ailing knee that had been affecting him for the majority of the season. In 1991, Tony Gwynn tried microfracture surgery in an attempt to restore cartilage in his balky left knee.

According to Wikipedia:

Microfracture surgery is an orthopedic surgical technique that can help restore knee cartilage by creating tiny fractures in the adjacent bones, causing new cartilage to develop. It can be used to treat both degenerative knee problems as well as cartilage injuries, and has gained a high profile in the sports world in recent years; numerous professional athletes including members of the NBA, NFL and NHL (most notably Steve Yzerman and Amare Stoudemire) have undergone the procedure.
The surgery is quick (taking around 30 minutes), minimally invasive, and has significantly shorter recovery times than an arthroplasty (knee replacement). Combined with a high rate of success, these factors have caused orthopedic surgeons to use the procedure with increasing frequency.