This is just a terrible, terrible injury. Texans right tackle Derek Newton went down without contact while attempting a block Von Miller against the Broncos, and had to be carted off the field after his legs were placed in air casts.
The extent of his injury was later revealed by NFL.com reporter Ian Rappaport:
This is awful. #Texans RT Derek Newton has torn both patella tendons, @MikeGarafolo & I report, and there is more damage. As bad as can be.
— Ian Rapoport (@RapSheet) October 25, 2016
Needless to say, an injury this severe is career threatening especially for a player of that size. Jimmy Graham and Victor Cruz have each torn patella tendons in a single knee, and have not been dominant since they have returned. This is why some doctors consider a patella tendon rupture to be worse than a torn ACL.