Barcelona confirmed on Tuesday that the 20-year-old Sweden international sustained the injury during training on Monday and will undergo surgery in the coming days. The club has not yet provided a recovery timeframe, although the nature of the injury is expected to keep him out for a lengthy period.
The setback is particularly cruel given Bardghji had been expected to find a new club before the September 1 transfer deadline.
Barcelona head coach Hansi Flick had told the youngster that he should seek a move because opportunities were likely to be limited during the upcoming campaign. Bardghji was subsequently omitted from the squad for recent friendlies against Nottingham Forest and Udinese as the club prepared for his departure.
Several European clubs had shown interest, with Premier League sides among those monitoring the winger. A loan or permanent transfer with a buy-back clause had been among the options being considered.
Instead, Bardghji now faces another lengthy rehabilitation after suffering the same injury in 2024 while playing for Copenhagen.
He joined Barcelona from the Danish club prior to the beginning of last season for around 2 million euros and made 28 appearances during his debut campaign, starting 10 matches. He scored twice and registered four assists as Barca won La Liga and the Spanish Super Cup.
Barcelona offered their support after confirming the diagnosis, posting a message to the winger on social media: "We are with you every step of the way, Roony. Stay strong."
Bardghji remains under contract at Camp Nou until 2029.