The 29-year-old, who has 36 Test caps for the All Blacks, has undergone surgery on a broken and dislocated finger suffered in the Crusaders game against the Bulls in Pretoria on April 9.
Maxwell's absence would leave All Blacks coach Graham Henry struggling to find an experienced partner for Chris Jack in the second row with Keith Robinson injured and Ali Williams still suspended.
Henry told the New Zealand Herald: "I know Norm is very concerned about his body and how it handles the load.
"But that final decision has not been made whether he will play international rugby or not."
Maxwell only returned to New Zealand rugby during last year's National Provincial Championship competition after taking a year out to travel and allow his body to recuperate from the rigours of almost 10 years of first-class rugby.
The second rower then toured Europe with the All Blacks at the end of 2004 which resulted in a delayed start for him with the Crusaders in the Super 12.