Surgeons confirmed on Wednesday that he had ruptured his medial ligament threrefore bringing a premature end to his season.
Vaesen will have an operation once the swelling in the knee has gone down and he is expected to be out for about six months.
“I am very, very hopeful of being back and ready to play for the start of next season. I am disappointed about getting injured because it was a freak accident," the Blues keeper told the Birmingham Post
“I felt my knee go back and knew it was something serious, but I was really pleased with the result the lads got and believe we just need a couple more wins to stay in the Premiership now.”