Ridgers was injured in a first-half collision with a Belgian forward as he slid in to take the ball at East End Park.
The Tynecastle number two immediately looked in some distress and was carried off on a stretcher. The initial diagnosis from the Scotland medical staff was a knee injury but a scan will be needed in the coming days to determine the severity.
Tottenham goalkeeper Jordan Archer came on for Ridgers in the 42nd minute and was beaten by a clinical strike from Ziggy Badibanga.
With St Mirren's Grant Adam out with a leg fracture, Archer could be called on for the team's final two qualifiers for the UEFA U21 Championship against Luxembourg and Austria early next month as Billy Stark's side look to stay in the top two places and seal a play-off spot.
Meanwhile, the Republic of Ireland's U21s hopes of qualifying for the European Championship look doomed after they were beaten 1-0 at home by Turkey.
Oguzhan Ozyakup scored the only goal for the Turks in Sligo despite Ireland having a man advantage for the final 18 minutes after Muhammet Demir was sent-off.
Ireland now need to win their final two matches – away against Hungary and Italy – to have any chance of making the play-offs.