Jared Allen underwent knee surgery on Jan. 31, the same day he had the shoulder repaired, two NFL sources said.
Allen categorized the knee surgery as a "minor" cleanup job.
Allen said he hadn't had surgery since getting his tonsils out at the age of five.
Allen is coming off two surgeries as he enters the last season of a contract that includes a team-high base salary of $14,280,612 and cap number of $17,063,956.