The Brazil international potentially faces a six-week spell on the sidelines after picking up a muscular problem against Monaco.
The Brazil international featured from the start in the Ligue 1 clash but was forced to leave the pitch after just 15 minutes of play after struggling with the problem, with reports in France suggesting the player could be out of action for a month and a half.
"He will have to undergo examinations on Monday or the day after," PSG coach Laurent Blanc told reporters when asked about Thiago Silva's fitness on Sunday.
"It's obviously a muscular problem so I think we have lost him for a little while."
The 29-year-old could miss the Ligue 1 games against Valenciennes, Toulouse and Olympique de Marseille, while he is also likely to have to watch the Champions League game against Benfica from the stands.
Radamel Falcao equalized Zlatan Ibrahimovic's early goal to keep Monaco two points clear of PSG at the top of the table on Sunday.