George, 19, made her England debut in both ODI and IT20 cricket in 2018 and impressed with her pace and ability to swing the ball.
She was continuing to work with England Academy coaches at Loughborough when the problem was discovered.
England coach Mark Robinson said: "We are all really gutted for Katie who showed so much promise last summer."
"Unfortunately though she hasn't really been fit since our summer internationals against New Zealand.
"She is obviously young and although it is a blow, she should - with a lot of hard work - hopefully be back to compete for a place again next summer."
© Cricket World 2018