Ryan Howard requires a surgical procedure on his left knee and will be lost to the Phillies from six to eight weeks, general manager Ruben Amaro Jr. said Monday.

Howard was placed on the disabled list Saturday, and an MRI and an x-ray Monday revealed that he had a torn medial meniscus, according to Amaro.

“It is not that dissimilar from what Erik Kratz had, and Erik is actually playing now,” Amaro said before the Phillies played the Washington Nationals. “He moved pretty quickly. Hopefully, we will have the same time frame, but everybody's knee is different.”

In 286 at-bats, Howard was hitting .266 with 11 home runs and 95 strikeouts.

“We can only speculate the length of how long it is going to take him to rehab,” Amaro said. “But we will shoot for the conservative one and hope that it comes back faster.

“I'm encouraged,” Amaro added. “It could have been much more significant damage. Obviously we don't want any of our players to be on the D.L. For long. But we know what it is. We know it is treatable. And hopefully we can have him back in time to play in the course of this year.”