A scan late last week confirmed he had the stress fracture in the fifth metatarsal of his right foot, the bone running down the outside of the foot to the little toe.
“The injury is obviously disappointing, but it’s not likely to be one that will bother me in the long term,” he said.
“I’ll have the operation and then get on with my rehab and look forward to turning out for the Crusaders when I’m given the all-clear by the medical staff.”
McCaw saw a foot and ankle surgeon in Christchurch on Tuesday and has been booked for surgery to insert a small screw into the bone.
Metatarsal injuries have been common among footballers in the English Premier League with Manchester United striker Wayne Rooney and Liverpool midfielder Stephen Gerard both suffering an injury to the fifth metatarsal in 2004.
Gerard was out for 10 weeks while Rooney spent 14 weeks on the sidelines.
Crusaders back Sonny Bill Williams is also hampered by a stress fracture to his left fibula in his left leg.
With the third and final Bledisloe Cup encounter for 2018 drawing ever closer, in partnership with Sage, premium partner of the Invictus Games, we look at how a greater sense of accountability in the forwards can help Australia match it with the All Blacks.
A while ago I got into a few discussions about the approach to carrying the ball into contact and thought it might be interesting to have a look at some of the prevailing approaches to the carry, who is being responsible for the carry and how it affects both attack and defence.