"Chet is in the process of undergoing evaluation, and when we have an update, we will communicate," the spokesperson told ESPN.
Holmgren, the No. 2 overall pick in this year's NBA draft, suffered the injury early in the CrawsOver Pro-Am event while defending LeBron James on a fast break.
The game was canceled in the second quarter because of the condition of the court. The unusually humid day in Seattle combined with a full crowd caused repeated wet spots and condensation.
The 7-foot-1, 195-pound Holmgren averaged 14.0 points and 8.4 rebounds in five games for the Thunder earlier this year at the Las Vegas Summer League.