Derek Rivers Reportedly Tears ACL; Patriots Fear Knee Injury Is Season-Ending

There is concern from the New England Patriots that rookie defensive end Derek Rivers suffered a season-ending knee injury during the team's joint practice with the Houston Texans on Wednesday. 

The initial MRI results revealed a torn ACL and sprained LCL, per Ian Rapoport of NFL Network.

ESPN's Field Yates and Mike Reiss reported the Patriots "fear" Rivers will miss the entire 2017 season after injuring his left leg. 

Reiss reported Thursday that Rivers was "walking with a noticeable limp" following a kickoff drill against the Texans, and he returned to Boston for more tests on his knee and leg. 

Comcast SportsNet's Phil Perry noted Rivers' "left leg seemed to buckle underneath him" as he tried to plant his foot and change direction. 

Rivers was New England's top draft pick in 2017, selected 83rd overall out of Youngstown State. The 23-year-old recorded 173 total tackles, 56.5 tackles for loss and 37.5 sacks in four college seasons.

The Patriots added Rivers to give them depth on the defensive line. The defending Super Bowl champions have already lost Rob Ninkovich, who announced his retirement on July 30. Rookie Deatrich Wise Jr. suffered a head injury in the preseason opener against Jacksonville on Aug. 10. 

With Rivers' injury, the Patriots are very thin on the defensive line right now. Trey Flowers and Kony Ealy are listed as the two starting defensive ends on the team's depth chart, and Rivers is Flowers' backup, with Caleb Kidder as third-stringer.