Corey Hart was scheduled to undergo a debridement of the right knee joint surface and repair a meniscal tear on Friday. Hart was originally scheduled to go under the knife on Tuesday, but he decided to get a second opinion first. The Brewers are waiting for a post-op report before they reveal how long Hart will be sidelined, but it's expected to be 3-4 months. Milwaukee will use Mat Gamel at first base until Hart is ready to return.