The Curacao-born midfielder has been in excellent form for the Midlanders, with boss Lee Bowyer admitting it is a real blow to be losing his services.
United confirmed on Wednesday morning: "Tahith has undergone surgery to repair a ruptured thigh tendon, the operation went well, and he will return to Manchester United to complete an expected four to five-month rehabilitation."
Chong was gaining plenty of experience in the Championship and had impressed in different roles for Bowyer's Blues.
The Birmingham manager told the club's official website: "Unfortunately, he had to have an operation today, 16 weeks he's now out for.