It's been a  year to forget for promising key position player Tom Curran.  Just 12 weeks ago, the 19-year-old had surgery to insert a bone in his foot and unfortunately, things haven't healed as well as expected.

The youngster will require more surgery on his troublesome right foot.

"Scans have shown after the last surgery Tom had on his navicular that the bone isn't re-growing the way we would like it to," Director of Medical Services Steve Saunders told NMFC.com.au.

"The surgeon wants to go in again to do a bone graft to stimulate better healing. Unfortunately it is a notorious bone for doing this."

This Thursday will be the third time the unlucky forward has gone under the knife in just two seasons at North Melbourne.

"Unfortunately it's a process Tom knows far too well but we're comfortable the bone has good blood supply," Saunders said.

"This is the highest level of intervention you can do with this sort of thing but we're pretty optimistic this will turn him around.  We've sourced three different opinions and they're all the same with what needs to be done."

Curran is expected to begin running again by Christmas.

"We're 12 weeks down the track from the last bit of surgery and now we're doing it again. So we're effectively 12 weeks behind where we thought we were going to be," Saunders said.

"If everything goes according to plan, we'll have him doing some running by the end of the year. It's hard to put a time frame on this because we're waiting for bone to heal and it does so at different rates in different people.

"The initial three or four months or so will be about how well his bone is growing and recovering while we do as much other type of training as we can.

"He's coping really well but it's an incredibly challenging time for him."

After missing North's 10-point win over Geelong on Friday night with back soreness, Nathan Grima could return this week to play Adelaide.

"Narny copped a knock in the game against Melbourne and his back hadn't settled as we would have liked.  We decided it was better to have him miss one, maybe two worst-case, and set him up for the rest of the year."

Cameron Delaney, a late withdrawal with a toe injury, will be monitored closely.

"Cam's (Delaney) had some pain in the big toe of his left foot which only just presented last week.

"He's had a previous history with the other foot that he's had surgery on a couple of years ago. It hadn't settled enough by game day so we didn't play him."

A call on his treatment plan is imminent.

"We'll have to make a decision over the next week or two whether we need to intervene and have surgery so his preseason isn't interrupted. Or it may be the sort of thing he can continue playing with and manage conservatively."

In the VFL on Sunday Max Warren got through unscathed in his first game back since surgery to repair his broken collarbone.

Nathan Grima - back - (test)
Cameron Delaney - toe - (test)
Andrew Swallow - achilles - (season)
Tom Curran - foot - (season)
Mason Wood - knee - (season)