Powell has not played any football for Man United since being forced off before half-time in a game against Everton in February.
It was hoped that the youngster would be back quickly but reports from Ian Ladyman suggested it was worse than first thought and that Powell would be out of action for a number of weeks.
The player himself tweeted to indicate he is recovering from the injury and that he was confident about a return:
Road to Recovery starts now.
Powell was highly-rated when he arrived at United from Crewe Alexandra in the summer of 2012. However, injuries and a lack of form have contributed to a disappointing spell at Old Trafford so far.
The 20-year-old spent time on loan at Wigan Athletic and Leicester City but never really made a big impact despite impressing in patches.
He will be hoping to force his way into van Gaal’s future plans but it appears unlikely that he will be at United for much longer.