De Laet was carried off on a stretcher towards the end of the Foxes 1-0 home defeat on Saturday following a challenge from Owls midfielder Jeremy Helan, and his right leg was placed in a splint.
Leicester boss Nigel Pearson said: "I don't think there was any malice in the challenge.
"I have seen it again. Ritchie went to make contact with the ball and we are talking about a contact where players are moving in different directions.
"It is his right leg. It is the fibula or ankle area. It is a contact of his lower limb and the extent is unclear at the moment. We hope it isn't too serious."
Pearson may have to dip into the loan market for a right-back to cover for De Laet if the injury proves to be a long-term problem, and the manager added: "I don't know at the moment if we have to go into the loan market. It is something we might need to consider."
- Sports & Recreation
- Nigel Pearson