Kommer had a impressive debut last year and played 19 games but he is yet to return this season because of a knee injury.

Hams, who played two games last year, has gone under the knife to repair a psoas tendon in his midriff.

"With Nick, he has been really chronic with patella tendonitis which we rarely operate on," club doctor Bruce Reid told the Essendon website.

"But he's had a very successful operation."

Reid added that Hams had been unable to train for 10 weeks and the Bombers "bit the bullet" by opting for surgery, rather than wait until the end of the season.

"We need to look long-term with both of them," he said.

It is unclear when either player will be ready to play again, with Essendon reporting the duo will be unable to train for several weeks.

After a promising start to the season, Essendon sits 11th and have the bye this weekend before facing Richmond at the MCG next Saturday.