The All Blacks host England, who pushed Hansen's men close at Twickenham in November, for three tests in June.
Screws holding bones together are nothing new to McCaw, who played through the 2011 World Cup with severe pain in his foot. The screws inserted into a stress fracture ended up exacerbating the problem - the irritation meant he hardly trained before the World Cup final victory over France.
His latest problem came midway through the first half of the Blues' stunning 35-24 victory over the Crusaders at Eden Park on Friday night, a win which could set alight the season for Sir John Kirwan's men.
It left him in pain and unable to grip anything with his left hand and he was replaced by Matt Todd at halftime.
Crusaders coach Todd Blackadder delivered the initial news about McCaw's thumb after watching his team blow a 17-3 lead and concede 29 unanswered points as the Blues gleefully accepted every opportunity.
Blackadder has big decisions to make this week - including whether to stick with Tom Taylor at first-five or switch Colin Slade from fullback, which appears likely. If he goes for Slade at No10, the 26-year-old will be the Crusaders' third first-five in three weeks.
Tyler Bleyendaal was dropped after his inaccurate performance there against the Chiefs in Christchurch, with fullback Israel Dagg also a casualty. However, Dagg played well when coming on at fullback in the second half at Eden Park and can probably expect to start there against the Stormers in Christchurch on Saturday.
While the Crusaders have no competition points and little form to speak of, the Blues have arrived in South Africa upbeat after a precious victory over the old enemy.
Their five competition points put them second in the New Zealand conference behind the Chiefs, who have eight points from their narrow wins over the Crusaders and Highlanders.
The Blues face the Bulls at Loftus Versfeld and the Lions at Ellis Park, two fixtures which are decidedly winnable with the likes of Patrick Tuipulotu, Tevita Li, Frank Halai, George Moala, Charles Piutau, Jackson Willison and Simon Hickey in form. Hickey, a 20-year-old on debut at this level, kicked six from seven shots at goal and hardly missed a beat.
Kirwan, who was granted a two-year extension to his contract last week, just one match into the new season, was cautious in his expectations but the future appears bright for both Hickey and the Blues if they can play with the confidence and flair they did in putting the seven-time champions to the sword.
McCaw's medical file
Concussion: 2004, 2005, 2009
Knee: 2008, 2009, 2013
Foot: 2011
Calf: 2013
Thumb: 2014
