The strong-bodied midfielder, who finished fifth in the 2013 best and fairest, has lacerated skin on his knee from Patrick Dangefield's boot.
RELATED: In the mix: Round 5
Club Physio Andrew Wallis told SAINTS.com.au on Tuesday that he expects Armitage to make a full recovery in time for St Kilda's Anzac Day match against Brisbane in Wellington.
"He had to have stitches in it [and] he is struggling to bend his knee so we’ve ruled him out for a week but he will be right the week after," Wallis said.
The left-footer has become an integral member of the Saints engine room in recent years, topping the club for tackles and running and close second for clearances last season.
Armitage has missed just three games since the end of 2010, highlighting his durability and importance to St Kilda's midfield group.
