Maholm, who was injured trying to cover first base, had an MRI on the knee on Saturday. The 32-year-old, who is a 10-year veteran of the Pirates, Cubs, Braves and Dodgers, was 1-5 with a 4.84 ERA in 30 appearances (eight starts) this season. He is 77-100 with a 4.30 ERA in 273 career appearances (250 starts).
"He was walking pretty good and then he hit the step and it collapsed," said Dodgers manager Don Mattingly. "I think he's had about four surgeries on the other one. This was the good one."
Maholm, who collapsed after the play but walked off the field without assistance, was an option to return to L.A.'s rotation with Dan Haren struggling.
The Dodgers (62-48) enter Saturday leading the NL West by 2.5 games over the Giants.
- Chris Mascaro