MELBOURNE will be unable to upgrade a player from its rookie list in place of retired defender Heritier Lumumba.

The Demons released Lumumba from his contract after the two parties reached an undisclosed settlement on Wednesday.

AFL.com.au understands the settlement involved Melbourne terminating Lumumba's contract for the 2017 season, meaning the club can not elevate a rookie player to replace the 223-gamer on its primary list.

If Lumumba had remained a contracted player it is believed under AFL guidelines the Demons would have had the option of placing him on their long-term injury list and promoting a rookie.

Former Brisbane Lions player Justin Clarke was in a similar, but unrelated, situation after he was forced to retire from the game in March 2016 after suffering ongoing concussion symptoms.

Clarke remained contracted to the club for the 2016 season, allowing the Lions to promote rookie Jackson Paine to their senior list in May.

Lumumba became embroiled in a dispute with the club over its handling of his repeat concussion symptoms and failed to train with his teammates when they returned in late November.

The 30-year-old received advice from medical experts that the risk associated with another head knock could have led to further complications for his long-term health.

However, the tests cleared Lumumba of ongoing concussion symptoms and there were no signs of long-term damage as a result of the head knocks.

Defender Mitch White is the only player with AFL experience – three games – on Melbourne's rookie list and would be one of the first in line to earn a call up if injuries struck.

Despite battling lingering groin soreness throughout 2016, agile forward Joel Smith displayed promising signs when playing for VFL affiliate the Casey Scorpions.

Smith, the son of former Melbourne high-flyer Shaun, has made the transition from basketball and has strong athletic attributes.

The 20-year-old could surprise a few and come into contention for senior football next season, such has been the rate of his improvement.

Young ruckman Lachlan Filipovic has potential but will be given time to develop, while mature-age Casey rookie draftees Declan Keilty and Tim Smith are ready to play if called upon.

Corey Maynard, the brother of Collingwood's Brayden, is the other rookie on the club's list, but as a category B rookie making the leap from basketball, he will be given at least a year of development in the VFL.