Glasby has not played since being replaced in the first half of the Knights clash against the Cowboys in Townsville in late June and following a series of medical tests, it now appears certain he won't play again.

The club has forwarded reports from his specialists onto the NRL for assessment and are currently waiting to find out if the former Queensland Origin prop will be medically retired.

The Knights will receive salary cap relief if he is.

Glasby is part of a horror injury toll for the Knights, who will have more than a quarter of their squad unavailable for Sunday's clash against Melbourne on the Sunshine Coast.

Sione Mata'utia is the latest casualty with the backrower set to undergo ankle surgery this week that will sideline him for six weeks. He joins Jayden Brailey, Andrew McCullough and Connor Watson [out for the season] and Edrick Lee, Daniel Saifiti and Brodie Jones on the injured list.

Glasby's manager Allan Gainey told the Newcastle Herald the 32-year-old prop is virtually resigned to his fate.

"It's highly likely it is going to be career-ending unfortunately," Gainey said.

"Tim's not good. He's still getting headaches. I spoke to him a few days back and he said they had eased but they are still there and it's more than a month since he last played."

Gainey said the NRL's chief medical officer Dr Paul Bloomfield's advice is for Glasby to not play again.

"There is a report from Bloomfield saying it is in Tim's best interests to pull the plug," he said. "They [the specialists] are saying if he was to come back and play, it will happen again."

It's understood Glasby, who has played 138 NRL games and made five Origin appearances for the Maroons, has suffered multiple head knocks this season including two in the one game.

His latest concussion came midway through the first half of the Cowboys game in round seven when he failed a HIA and did not return.

Knights CEO Phil Gardner said Glasby's health and welfare is paramount and must come first.

"Tim's had all his medicals done and we have put all that together in a report for the NRL to review and are waiting on the advice of the NRL in relation to the next step," Gardner told the Newcastle Herald.

Asked about the prospect of Glasby being medically retired, Gardner said:

"It's up to the NRL to decide whether he can be medically retired and we're not in a position to be pre-empting their decision on that."

Given the serious nature of his concussions and the NRL's stance on them, it is highly unlikely they will knock back the request.

Glasby still has a year to run on his contract at the Knights worth around $450,000 next season.

He will be entitled to a full pay-out if given the green light to retire by the NRL with his playing fee salary cap-exempt, giving the Knights the opportunity to sign a replacement middle forward.