Wall suffered the injury when he crashed to the floor after driving to the basket in the second quarter of the Wizards' 104-98 victory over the Atlanta Hawks in Game 1 of the Eastern Conference semi-finals.
Wall failed to recover in time for Game 2, which the Hawks won 106-90, and could miss the rest of the post-season after the fractures were confirmed.
The 24-year-old is now consulting with physicians and specialists to determine what his best course of action would be.
"Honestly have no idea if John will play," Wall's team-mate Bradley Beal told ESPN. "Praying for the best but prepared for the worst. We still feel like we have the tools and gameplan to win."
Should Wall be ruled out for the rest of the post-season, it would be a big blow for the Wizards since he has been averaging 17.4 points, 12.6 assists and 4.6 rebounds during the playoffs.