Arizona general manager Josh Byrnes said doctors performed a lateral release on the knee as well as microfracture procedure. A lateral release involves cutting tight structures to the outside of the kneecap that are causing the kneecap to tilt abnormally. Microfracture surgery is used to restore knee cartilage by creating tiny fractures in the adjacent bones, which causes new cartilage to develop.
Estimates on how long it could take Tracy to return are anywhere from four to eight months, according to manager Bob Melvin.
Byrnes seemed more confident that Tracy would be able to participate in Spring Training next year.
"There's some healing that needs to occur," Byrnes said. "It's kind of hard to pinpoint a timeline, but our best guess is in the five-month range."
Tracy had been bothered by pain in the knee throughout the season. He was on the disabled list most recently from Aug. 15 to Sept. 16, when he was activated and delivered a key pinch-hit single. The knee flared up while running the bases, and he was forced to have surgery.
The uncertainty as to when Tracy will return could hamper Arizona's offseason plan of alleviating its logjam at the corner infield positions.
Speaking of injuries: Second baseman Orlando Hudson, who underwent surgery to repair ligaments in his left thumb Sept. 10, had the stitches from the surgery removed Friday and had his cast changed.
Hudson said he was told the thumb was healing nicely and that he could have the pin removed from it Oct. 1.
Just another day: With the days in the season dwindling and the playoff race tightening, the D-backs' clubhouse still hasn't shown any signs of tension or nerves.
"For the guys in here, it's always just another game," veteran infielder Jeff Cirillo said. "I mean, everyone inside probably knows what these games mean, but outwardly, it's almost a robotic approach. It's another game on the schedule, and we play it."
And that's just the way Melvin wants them looking at things. Though he has been criticized at times for his stoic nature during games, it's a trait that has proved to be valuable with his young team in the midst of a tense pennant race.
When he was a player and then as an advance scout for the Brewers, Melvin formed his philosophy that players will panic and play tense if they sense their manager going through the same emotions.
"I think it kind of gives the players a sense of security that the guys that are running the show in here aren't falling off because of the scores or how the games are going. There's a little more sense of security and calmness and just playing the game out," he said.
It's a lesson even the team's youngest player, 20-year-old Justin Upton, has taken to heart.
"At the end of the night, if we drop one, we know that we're going to come back and play just as hard the next night," Upton said. "We don't worry about the outcome. We're more focused on just playing hard, and however it ends up, we deal with it."
Speaking of the pennant race: Melvin admitted that he checked out the Padres and Phillies games during Thursday's off-day.
"I looked at a few of them, but it wasn't a priority for me," Melvin said. "I just saw where things were during the day. If you're a baseball fan, I don't know how you can not love this time of year and what's going on. Baseball is a great sport, and right now, with the division races the way they are, it's a great time to be a baseball fan."
According to plan: When the D-backs signed reliever Bob Wickman in early September, the idea was to have him spell setup men Tony Pena and Brandon Lyon if needed, or pitch the sixth inning with Pena and Lyon combining for the seventh and eighth and Jose Valverde closing things out in the ninth.
The first time they had a chance to use the latter plan came in Wednesday night's win over the Giants.
"It worked nicely," Melvin said.
Up next: The D-backs and Dodgers continue their series Saturday night at Chase Field with D-backs ace Brandon Webb (16-10, 3.03 ERA) facing off against David Wells (8-8, 5.40) at 6:40 MT.
Wells will be pitching on just three days' rest.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.