The Panthers announced the injury designation on Tuesday.
"Matt Kalil traveled to Florida on Monday to receive a second opinion on his right knee from Dr. James Andrews," Panthers head athletic trainer Ryan Vermillion said in a statement. "After consulting with Dr. Andrews, the decision was made to perform an arthroscopic procedure on Matt's knee. He will be evaluated on a weekly basis."
Kalil, 29, was the No. 4 overall pick by the Minnesota Vikings in the 2012 NFL Draft. He played with the Vikings through the 2016 season before signing with the Panthers in 2017.
The 6-foot-7, 315-pound offensive lineman started all 16 games last season for the Panthers. He started just twice in 2016 for the Vikings, but has started all 16 games in five of his six NFL seasons, including his Pro Bowl rookie campaign.
Taylor Moton is likely to start at left tackle for the Panthers in Kalil's absence, with Jeremiah Sirles filling in at right tackle. Starting right tackle Daryl Williams suffered a dislocated right patella and torn MCL in his right knee during training camp and is out indefinitely. Left guard Amini Silatolu is also out with a torn meniscus in his left knee.
The Panthers also lost starting guard Andrew Norwell in free agency to the Jacksonville Jaguars. Kalil's brother, Ryan Kalil, is listed as the Panthers' starting center on their unofficial depth chart. Blaine Clausell is listed as the second string left tackle, with Sirles in reserve at left guard and right guard.