The 28-year-old sustained the injury while playing for the Casey Scorpions in a VFL practice match against Port Melbourne on Sunday.
General manager of football operations Josh Mahoney said Garland would miss the entire season after scans confirmed the worst.
“Unfortunately, scans have confirmed that Col has ruptured his ACL,” he told melbournefc.com.au.
“He will meet with a surgeon to discuss his options today (Monday) with the most likely option being that he will miss the year.
“After a disappointing season, last year, Col had completed a very good pre-season and set himself up for a good season.
Garland, who has played 141 games for Melbourne, only managed six games last season, after falling behind Oscar McDonald in the pecking order in defence at the Dees.