Hewitt – who has made 103 senior appearances for Dragons – sustained an ACL and MCL harm within the defeat at Rodney Parade.
The 26-year-old will now bear surgical procedure subsequent week earlier than beginning his rehabilitation and restoration course of.
Dean Ryan, Director of Dragons Rugby, mentioned: “It’s extremely disappointing information for Ashton who was enjoying some excellent rugby for us.
“He’ll now bear surgical procedure early subsequent week earlier than beginning his journey again from harm.
“All of us ship our greatest needs to Ashton and need him nicely together with his restoration.”