The midfielder said he first felt the injury during the World Cup, when doctors assured him it would not worsen even if he continued playing. Those assurances ultimately proved incorrect, with the issue getting worse rather than staying stable.
De Jong addressed the situation directly in a statement posted to Instagram, saying he wanted to set the record straight amid speculation about his relationship with the club.
The full statement read: "Normally, I don't pay much attention to what's written about me, but recently there has been a lot of speculation about my injury and my situation at Barcelona.
"It is difficult for me to see people questioning my relationship and my commitment to the club with fake news. Football is everything to me and I have always given everything for Barcelona and for my country, and that is why I want to share what has happened.
"During the World Cup I injured my knee. After the initial examinations, the doctors told me it was a minor injury and that it would not get worse if I continued playing. The only challenge was playing with a bit of pain, but throughout my career I have done everything necessary to help the team, my club and my country.
"During the holidays I returned to Barcelona for further tests. These showed that the injury was more serious than initially determined. Fortunately, in this condition surgery is not necessary and I am fully focused on my recovery and on returning to the pitch as soon as possible. Every day I work to be in the best possible shape. I take my profession, my body and my responsibility to the team very seriously. But sometimes there are things you cannot control, and this injury is one of them.
"Playing for Barcelona and for the national team makes me feel incredibly proud and my commitment to both will never change. I will continue to give everything for the badge, my team-mates and the supporters.
"There are still many moments to create and challenges I want us to achieve together. Thank you all for the support. I cannot wait to be back.
"Visca el Barca, sempre.
"Frenkie"