The Wellington Hurricanes outside back dislocated his shoulder during their Super Rugby victory over the Auckland Blues at Eden Park last weekend and scans showed the need for surgery, his team said on Wednesday.
Milner-Skudder made more clean breaks (14) and gained more metres (552) than any other player as New Zealand won a second successive World Cup last year.
"Losing Nehe is a blow and obviously disappointing for him," Hurricanes coach Chris Boyd said in a news release.
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"But we're really lucky in that we have a lot of depth in the outside backs and when you can bring a 53-test All Black like Cory Jane into the team, you aren't going too bad."
Jane will replace Milner-Skudder on the right wing when the Hurricanes take on Australia's Western Force on Friday and Boyd has also been able to give his captain, All Blacks hooker Dane Coles, his first game of the season.
"We've been a little unlucky with our hookers so far this season with injuries, so it's great to have Colesy back on the park," the coach added.
"He's our leader, he's a guy who the team looks to for direction and he's itching to play."
(Reporting by Nick Mulvenney, editing by Peter Rutherford)
