ESSENDON draftee Jordan Ridley will be sidelined for up to three months after it was revealed he had a stress fracture in his back.

The defender, who was drafted with pick No.22 in the 2016 NAB AFL draft, experienced discomfort during training last week, prompting the Bombers to investigate.

High performance manager Justin Crowe said the 18-year-old would need to avoid running for up six to eight weeks before building up to his playing return.

"Unfortunately Jordan has a partial stress fracture in his back, which in one sense gives us a chance to let it heal because it hasn’t broken through, so we’re going to take that opportunity," Crowe said on the club's website.

"He’s going to have six to eight weeks off running and then build back up into the season.

"The good news for Jordan is he really only needs to avoid impact – which means running … so he’ll be able to do a lot of weights over the next couple of months."

Ridley was the Bombers' second pick overall at last year's draft making his debut for the club against Gold Coast last month in the JLT Community Series.