England international Healey is to undergo exploratory knee surgery on Tuesday after being forced off during the latter stages of the defeat.
As well as being a setback for the team, this is also a major personal blow for Healey, the versatile back having spent more than three months on the sidelines already this season due to an Achilles' tendon injury.
Meanwhile, No.8 Will Johnson – brother of England and Tigers skipper Martin – has sustained knee ligament damage and will not play again this season.
"Will has sustained ligament damage to his knee and will be out of action for the rest of the season," said Leicester's Director of Rugby Dean Richards.
"Austin will undergo exploratory surgery on his knee tomorrow morning and until we receive those results we will not know the extent of his injury. It will obviously take some time for him to recover from tomorrow's operation."
Leicester have just three games left in their Zurich Premiership campaign – against NEC Harlequins, Leeds Tykes and London Irish – and will need to finish in third place to have any chance of defending their domestic title in the end-of-season play-offs.