Jackson fell awkwardly Saturday after getting tangled up with cornerback Asante Samuel during a full-squad drill.
The second-year pro walked the length of the field with head trainer Rick Burkholder before being carted to the locker room. Jackson was able to put weight on his leg after practice, but the knee was heavily wrapped.
A second-round draft pick in 2008, Jackson set the Eagles' single-season rookie record with 912 receiving yards. He also set the team's single-season rookie record for a wide receiver with 62 receptions.