Cardinals first baseman Lance Berkman will undergo surgery this week to address a right knee injury that, according to the club, might or might not require a season-ending replacement of the anterior cruciate ligament. An MRI Monday disclosed tearing of the meniscus and cartilage responsible for cushioning the knee. Berkman, a veteran of four knee operations, estimated he will be sidelined minimum of six weeks following the arthroscopic procedure while admitting that he might require a significantly more extensive procedure. "All the information I'm getting plus what I felt leads me to believe there is an issue with the ACL," he said. "I'm hoping that's not the case, but I'm not sure that's the case." Berkman consulted Monday with team medical supervisor Dr. George Paletta, who reviewed an MRI that found extensive cartilage damage to both sides of a knee that buckled as Berkman caught a routine throw from shortstop Rafael Furcal in the second inning Saturday at Dodger Stadium.