North Melbourne’s Aiden Bonar will undergo surgery on his left ankle.

The defender suffered a high-grade medial ligament injury in the third quarter on Saturday.

North GM football, Brady Rawlings, said it was another unfortunate and unavoidable long-term injury for the Kangaroos.

“Obviously it’ll be quite a lengthy rehab period which is unfortunate for Aiden and us,” Rawlings said.

“We’re hoping to get him back towards the end of the year with Round 15 being the best case at this stage.”

Bonar’s injury adds to the club’s long list of injury concerns.

“Our depth is being challenged,” Rawlings said.

“We will continue to focus on the opportunity it provides to our younger players to work on constant improvement.

Full injury report to come.