Mumford injured his ankle on Sunday afternoon against Collingwood, with scans revealing that he will require a full reconstruction to repair a torn deltoid ligament in his left ankle.
The 28-year-old will undergo reconstructive surgery later in the week.
“He’s an important part of our footy club and everyone’s aware of what he’s done so far in his short time here,” Coach Leon Cameron told the club website.
“It’s obviously disappointing to lose him, but the welfare of the player has to come first and the recommendation came pretty strongly to have a major operation on his ankle.”
Davis will miss six to eight weeks, after he sprained ligaments in his right ankle on the weekend, while Congilio is likely to only miss two games due to a grade two AC joint shoulder injury.
Read more at GWSGiants.com.au