The 22-year-old left Pandy Park in the early stages of Keys' 36-12 success over their English opponents and was immediately taken to hospital.
He has since had an operation to correct the problem but now faces a lengthy spell on the sidelines and isn't likely to return to action until late October at the earliest.
An eight-week absence would rule Jones out of the first five RaboDirect PRO12 fixtures and the Amlin Challenge Cup tie against Rugby Mogliano, while a 12-week lay off would also see him sit out the European clash with Bath and the league matches against the Ospreys, Leinster and the Scarlets.
And while new boss Lyn Jones has plenty of strength in depth in the No10 shirt thanks to the arrival of Italian international Kris Burton and the return of Jason Tovey, losing his young namesake is still a worry he could have done without as the Dragons look to improve on last year's 11th place PRO12 finish.
Jones featured in 22 games for the region last term and bagged a record-breaking 27-point haul against London Welsh as he exerted his growing influence at Rodney Parade.
Unfortunately for the Dragons, Jones wasn't the only injury victim this weekend despite the fact that the region weren't involved in pre-season competition.
A number of Dragons players played for Premiership clubs on Saturday and wing Will Harries joined Jones in picking up an injury that could affect his early season availability.
The Wales international failed to last the opening quarter of Newport's 40-23 defeat to Moseley at Billesely Common after he strained his hamstring.
No timeline has yet been set for Harries' return, with the 26-year-old currently being assessed by the Dragons medical staff.