Luke's scans revealed a tear of the anterior cruciate ligament, ruling her out of the remainder of this AFLW season, while Stephenson, qhio has been left with an ankle fracture, will not have a timetable for a return to play until after she undergoes surgery.
Hawthorn's football operations boss Josh Vanderloo confirmed everyone's worst fears but maintained the Hawks will support the dynamic duo through their rehabilitation process.
"Unfortunately, scans have confirmed the worst for two of our spirited leaders in Lou and Tam," Vanderloo said.
"The club will do all it can to support them through their rehabilitation."
The former Saint in Luke stood as a key piece of Hawthorn's inuagural campaign as a versatile key-position option at Waverley.
The Hawks will now turn their attention to Round 3 of season seven, when they face Richmond at Punt Road as they search for a maiden victory.