ESSENDON has received a double blow, with key position player Courtney Johns to undergo a full knee reconstruction and highly touted youngster David Myers to miss the next month with stress reaction in his right foot.

Johns, 23, was expected to require the season-ending operation after injuring his knee on Saturday while playing for the Bendigo Bombers.

Scans on Monday revealed a rupture of his left anterior cruciate ligament, which means the unlucky former rookie faces more time on the sidelines after previously battling chronic hip complaints.

"After the operation he will start rehabilitation and will be fit to play again in approximately eight or nine months," club doctor Bruce Reid said on the club's website.

"Most clubs have about one knee reconstruction a year so we have been lucky for the past six, seven years during which we only had two.

"Unfortunately we have had two this year with Alwyn and now Courtney so that's very disappointing."

Johns has managed just 21 games of senior football since his debut in 2005, owing to the persistent hip problems.

He will undergo the reconstruction in about two weeks.

Myers, 19, is set to be sidelined for the next four weeks after pulling up sore following the Bombers' four-point win over Fremantle at Subiaco last Sunday.

"With his stress reaction he simply got sore as the game went on and was really sore after the game. There was no real warning," Reid said.

"He has had scans and he has a hot spot in his foot – there is no fracture, it is just a stress reaction."

Reid said the club is not prepared to take any risks with its first pick in the 2007 NAB AFL Draft, and will allow the eight-gamer to rest without surgery. 

"We will put him in a 'moon boot' and let his foot heal naturally from there and then assess him again in a few weeks."