This was after the 25-year-old saw the surface of his left kneecap after splitting open the skin below the joint when he crashed into Patrick Dangerfield's boot in round four.
There's not much about the injury that isn't stomach churning - from the exposed patella that was immediately stitched, leaving Armitage play to out the game with bits of soil and grass inside his knee, to the infection that developed and the two procedures needed to kill the germs.
So it wasn't surprising the Saints who saw Armitage during his nine-night stay in The Avenue Hospital in Windsor had to avert their eyes.
Armitage recalls the incident in the loss to the Crows on April 13 but was more concerned about the suspected concussion he suffered when teammate James Gwilt crashed into him.
"I went to lunge to tackle Dangerfield and I remember Jimmy coming the other way and he sort of clipped my head and at the time, I didn't think too much about my knee, I was more worried about my head," Armitage told AFL.com.au after he was released from hospital on Wednesday.
"I hopped up off the ground and the docs were there at that stage and asked if I was OK, I said 'Yes, but I've had a head knock and my knee is starting to hurt.'
"I looked down and the doc saw my reaction to what I'd just looked at.
"I could see a big open wound; it wasn't bleeding or anything but it was right down to the flashing of the kneecap and it was pretty gruesome."
Armitage was patched up with 10 stitches, cleared of concussion, given a painkiller and played out the game.
He slept well that night before heading into the club the next morning.
By Monday night, he could barely walk and rang the club doctor for help.
The next thing he knew, he was in hospital on an antibiotic drip.
On Tuesday, Armitage thought he was on the mend. The pain had subsided and he was feeling better.
But when he took the dressing off the next morning after having a shower, there were swollen red patches on each side of the cut.
He went into surgery that night to have the wound cleaned and swabbed for bacteria, and came out with the cavity packed with foam dressing and attached to a vacuum pump machine.
The wound had to stay open to dry out naturally, with the pump creating a seal around it and sucking out any infection.
"It was just a big hole all the way across my knee," Armitage said.
"They had to cut away at the dead bacteria … so it was pretty gruesome."
After four days of watching the machine suck out unwanted matter, Armitage was taken back into surgery to see if the process had been successful.
He was told beforehand there was a 90 per cent chance they would be able to remove the pump, close the wound and let him go home within days.
Luckily, that happened and he was released on Wednesday morning with his leg bandaged and in a brace that stops the knee from bending.
Tests on the bacteria in his knee showed he picked up the germ from the soil at Etihad Stadium. Armitage was told the possibility for infections from sporting surfaces was always high and said he was just unlucky.
While resting at home ahead of the removal of his brace on Monday, he had already noticed deterioration in his left quad and calf from inactivity.
So he's realistic that while he'll be at the club next week in a less cumbersome brace, he'll probably need all of the next four weeks to get himself ready to play again.
This means it's likely he won't return to the field until after the Saints' round 10 bye.
"Personally, I'm going to try and get back as quick as I can … I'll try and persuade the doctors and physios as well," he said.
"But they know what they're talking about … I'm hopeful but it's probably not looking like [being before that]. It could be a lot quicker than that so let's hope so."