It leaves the Panthers without a key cog on their offensive line starting with Sunday's season opener at the New York Giants, with Geoff Schwartz expected to start in Otah's place.
"I had a mini-setback," Otah said. "Things didn't go as planned."
The 6-foot-6, 335-pound Otah first had surgery in December to repair torn cartilage that knocked him out of the final three games. Otah had continued pain when players reported to training camp and was placed on the physically unable to perform list.
Otah had another arthroscopic procedure on the same knee on Aug. 4. He was recovering from that when the pain returned recently while he was running.
"I might have pushed myself a little too hard coming back. Then I had a setback," said Otah, who hasn't practiced since training camp began. "Little upset with that, but I've got to move on and try to get back out there."
Schwartz proved to be a capable backup as a rookie last year starting in Otah's place in the final three games, including in Carolina's 41-9 win over the Giants when Jonathan Stewart rushed for 206 yards.
But behind the starting line is uncertainty. The only other linemen on the roster are Garry Williams, who played in seven games mostly on special teams as an undrafted rookie last year, and Tim Duckworth, a journeyman who signed with Carolina on Aug. 30.
"Either way, most people are only going to be able to suit up seven or eight of them," coach John Fox said of the offensive line. "I feel comfortable with that."
Otah, who became an immediate starter after being a first-round pick in 2008, said he hasn't had swelling in the knee, just nagging pain.
"I didn't expect it to take this long. It's frustrating," Otah said. "All I can do is try to rehab as hard as I can and get back out there."
Copyright 2010 by The Associated Press
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