Coach John Kirwan said he was aware of the "clean-up'' procedure and possible delay.
All Blacks' second-five Nonu was troubled by the injury last year.
There will be external pressure on Nonu to prove his worth at the Blues after he reneged on a handshake deal with Kirwan in what was the coach's first season in charge last year - instead choosing to join the Highlanders.
While Kirwan was disappointed by the snub at the time, he might have thought otherwise as he watched Nonu struggle with form and discipline as the Highlanders slumped to 14th out of 15 teams, winning only three matches. His form for the All Blacks meanwhile was consistently high, including in the June internationals against France.
Nonu finished the All Blacks' unbeaten season last year rated by most observers as the world's best midfielder.
Returning to fulltime Super Rugby duty yesterday along with his All Blacks teammates following their extended break, Kirwan said Nonu, a 31-year-old veteran of 88 tests, had done everything required of him.
"As far as I'm concerned, every communication I've had with him since he's signed has been fantastic,'' Kirwan, who was unwilling to predict when Nonu would return, said. "He's done everything he needs to do.
"He wants to play, but I'm just going to hold him back like we will with the others [All Blacks].''
Asked if it was realistic for players to maintain their form from February to late November, Kirwan said the important thing was to treat each player as an individual.
"It's an interesting challenge; I think everyone's different. What we're trying to create here at the Blues is to treat everyone differently. Some people can hit form early, some people hit form later, but the first thing we want to do is to make sure they're well physically.''
All Blacks prop Tony Woodcock's hamstring injury from late last year will be monitored following his return.
None of the senior All Blacks are likely to be available for the Blues' three pre-season games, starting with the Hurricanes in Masterton on Saturday, Kirwan said.
Halfback Piri Weepu, who has had knee surgery, could play in the third warm-up game against the Chiefs in Rotorua on February 14.
Chris Noakes will not be available for Saturday's match due to his neck problem, meaning Benji Marshall and Baden Kerr will both spend time at first-five.
- by Patrick McKendry of APNZ
