Braithwaite could now be sidelined through injury until 2022.
Former Leganes attacker netted twice in La Blaugrana’s season opening 4-2 win over Real Sociedad before being forced off injured against Getafe two weeks later.
Braithwaite has not featured for Ronald Koeman’s side since then but initial estimates hinted at a minor knee injury for the 30-year-old.
However, he was permitted to join up with the Danish national team this month, but failed to prove his fitness to Kasper Hjulmand.
According to reports from Marca, Braithwaite has undergone further tests on the problem upon his return to Catalonia and he could now miss four months of action.
A final decision on the next step will be taken in the next 24 hours with Barcelona’s medical team expected to give a firm recommendation tomorrow, with surgery a remaining possibility.
Braithwaite’s expected absence will provide a immediate first team chance for deadline day signing Luuk de Jong following his loan switch from rivals Sevilla.