MELBOURNE defender Meg Downie will miss the remainder of the AFL Women's season due to a ruptured hamstring rather than concussion.

Downie was hospitalised on the weekend after being knocked out in an illegal hit by Collingwood forward Sophie Casey, who copped a two-match ban, during Melbourne's 19-point win on Saturday night.

But the club said Downie ruptured her hamstring moments before the collision.

Demons Women's football operations manager Debbie Lee said the club initially thought Downie was just affected by the concussion when she told the medical staff of the hamstring injury.

"The medical team thought she was still concussed when talking about it, but Meg was quite right," Lee said.

"We got an MRI scan on Monday and unfortunately the results weren't what we were hoping."

The Demons have also lost Stephanie De Bortoli for the season after she required surgery to repair a damaged Achilles tendon.

Meanwhile, Fremantle's Kim Mickle will also miss the season after rupturing her ACL during Sunday's clash against the Brisbane Lions.

Teammate Brianna Green is another long-term casualty after breaking her collarbone during the second quarter of the match.

Green saw a surgeon on Monday, and is waiting on medical advice to determine if she is required to undergo surgery.