The 32-year-old French rider crashed on the Route de Marquette cobbled sector, 155km into the 198km race, and apparently briefly lost consciousness. He was treated at the scene before being transported to Lille University Hospital by helicopter.
On Sunday evening, a press release from Wanty-Groupe Gobert said that Offredo was in a stable condition at the hospital.
"Yoann was never in a life-threatening situation," the statement read. "He will undergo additional examinations over the upcoming night in observation. A medical report should be made up on Monday."
Initial reports from both his team and local newspaper La Voix du Nord described Offredo as conscious but suffering from injuries to his neck and back. Later on in the afternoon, the same newspaper reported that a CT scan had returned positive news, with no broken bones and no threat to Offredo's life.
After the Nokere Koerse fours days previously, the GP de Denain was Offredo's second race back in the peloton after what had been almost a month out following severe fatigue due to a virus he had been suffering since the start of the year.
He's currently in the midst of his third season with Wanty, having spent the first 10 years of his career at Groupama-FDJ.