An X-ray on Saturday night proved inconclusive, but scans have now shown up a double tear to the tissue around the hip, meaning he will sit out the Tynecastle meeting with Saints.
A statement on the Aberdeen website said: "Scans have this morning revealed that Ryan Jack will be sidelined for six to eight weeks following the injury incurred during Saturday's match against Motherwell.
"Ryan has suffered a double tear in the hip area and will now sadly miss our semi-final against St Johnstone this weekend.
"Everyone at the club wishes him a speedy recovery."
Hutchinson was booked for the tackle, but Dons boss Derek McInnes thought the defender deserved a red card, saying after the match: "Regardless of how long he is out for, I thought it was a poor challenge.
"I know there is a touch on the ball from Hutchison but for me there is only someone going to get hurt in that challenge.
"It is reckless at the very least.
"In real time I did wince. I thought it was a straight red and having seen it again, I think you would lean more towards a red than a yellow."
Right-back Shaleum Logan is in line for his debut after joining from Brentford.
St Johnstone will put their faith in 41-year-old goalkeeper Steve Banks after regular number one Alan Mannus was ruled out for six weeks.
The Northern Irishman - suspended for the Tynecastle clash - has also suffered a fractured thumb and Banks will take over.
Former Scotland striker Chris Iwelumo could make his Saints debut but defender Tam Scobbie is suspended while midfielder Murray Davidson and striker Steven McLean (both knee) remain on the sidelines.
- Sports & Recreation
- Shaun Hutchinson