Adelaide defender Brent Reilly will miss the rest of the season with a shoulder injury.

Reilly needs surgery which will sideline him between three and six months, Crows coach Brenton Sanderson says.

Adelaide's Brent Reilly of the Crows is helped from the field. Credit:Getty Images

Reilly was hurt in the opening minute of last Saturday's win against Gold Coast – his comeback match after being dropped and told to lose some weight by coaching staff.

"It has been one of those years for Brent," Sanderson said on Wednesday.