Cook has been ruled out for between six and nine months after rupturing the anterior cruciate ligament in his right knee, as reported by BBC Sport.
The 21-year-old midfielder suffered the long-term injury during Bournemouth’s Premier League game against Huddersfield Town on Tuesday evening.
Leeds defender Cooper - who is himself on the sidelines at the moment with a knee injury that will keep him out for up six weeks, according to BBC Sport - has wished his former Leeds teammate Cook a speedy recovery on Twitter.
All the best mate! Wishing you a speedy recovery https://t.co/e9nBNmIPGH— Liam Cooper (@LiamCooper__) December 8, 2018
Cook started his professional club football career at Leeds and joined Bournemouth in the summer of 2016 for an initial transfer fee reported by The Guardian to be worth £6 million.
The 21-year-old midfielder - who earns £30,000 per week as salary, according to Spotrac.com - made 25 starts and four substitute appearances in the Premier League for Bournemouth last season, according to WhoScored.