I have intimate details about dislocated kneecaps (4-Time Sufferer)
-Freshman Year Soccer -- by far the worst pain I've ever felt -- excruciating pain -- kneecap was stuck behind the knee, stretching/straining the ligaments until doctors at the hospital were about to pop it back in after being loaded up on what seemed like every drug (with a little over a month of extensive rehab everyday I was ready for winter basketball season)
-Junior Year Soccer -- Summer Workouts (End of Aug) -- again stuck behind the knee -- made it back towards the end of the season (End of Oct) for it to only pop out (stuck) again. Good Times.
- Junior Year Baseball -- Inside pitch hit directly on the side of my knee and it popped out, but for the first time popped back in instantly (out for about a Week and a half)
Senior year and college baseball - along with the rest of my life - it's thankfully never happened again -- it is however always in the back of my mind.
Sucks for Mahomes -- if no ligament damage probably looking at about 3-4 Weeks (month).
Pray for no ligament damage.