Troisi will be out of action for at least a month after having an operation on Tuesday on a bone spur on his right knee.

The veteran midfielder's hopes of playing again in the disrupted season hinge on seventh-placed Adelaide making the finals, which are likely to start around August 21.

Football Federation Australia will announce the season schedule later Tuesday.

Troisi endured a troubled campaign before the league was suspended amid the coronavirus pandemic, playing 13 of a possible 21 games.

The 32-year-old missed a chunk of games in February because of a thigh strain, and was sidelined by a hamstring strain in January.

On return to training after the season shutdown, Troisi battled knee soreness but played in Adelaide's two internal trial games.

"The problem James has had has been a consistent source of discomfort to him for some time and has prevented him training fully," Adelaide's club doctor James Ilic said.

"The issue was a bony spur on the outside of his knee that was persistently irritating him during movement."

Troisi's injury puts another hole in an Adelaide midfield missing international Mirko Boland, who remains in Germany during the pandemic.

The Reds also cut ties with Dutch-based defender Michael Maria and parted company with coach Gertjan Verbeek, who won't be returning from the Netherlands.

United appointed Carl Veart as interim coach for the rest of the season.

Australian Associated Press