Kelce was carted off the field during the Eagle's win against the Baltimore Ravens at Lincoln Financial Field on Sunday.
During a news conference on Monday, Eagles trainer Rick Burkholder said Kelce suffered a partial ACL tear and a full MCL tear.
Burkholder went on to say that there is no a consensus among sports medical professionals across the country about how to handle this situation.
The first thing that needs to happen, Burkholder said, is for MCL heal before anything can be done with the ACL. That takes 4-6 weeks.
Then, they will need to decide whether to fix the ACL, putting Kelce out for the season, or see if it will heal on its own. If that happens, Kelce may return this season.
Kelce will have another knee examination on Tuesday.
The Eagles won 24-23 over the Ravens.
Dallas Reynolds replaced Kelce, taking his first NFL snap after spending three seasons on the practice squad.