Robinson could miss the rest of the season after a scan showed torn cartilage.
The 20-year-old did not play in Saturday's defeat by Inverness and will miss the match against St Mirren tomorrow night - a dress rehearsal for the Scottish Communities League Cup final on March 17.
Hearts manager John McGlynn said: "Scott Robinson has picked up a recurrence of a knee injury and has a tear in his meniscus, which is not great.
"It was an injury that recurred during the Hibs game (on January 3).
"We tried to give it some time but it came back again. He had a scan yesterday which showed up exactly what it was.
"Worst-case scenario, he would need a wee tidy-up (operation).
"It may well be you can nurse it through to the end of the season but we are talking ifs and buts.
"He has another opinion to get from a specialist and we'll talk with Scott and see what's the best way to go about it."
Hearts are without midfielders Scott Robinson and Ryan Stevenson for the Clydesdale Bank Premier League clash at St Mirren Park.
Robinson has a knee injury that might require surgery while Stevenson completes a three-match ban following his red card against Dundee United.
Long-term absentees Danny Grainger (knee) Marius Zaliukas (ankle) and Callum Patterson (foot) remain on the sidelines while Jamie Hamill is still working his way back from knee surgery.
Meanwhile, St Mirren winger Gary Teale will sit out the third match in a row for the Buddies.
The former Scotland cap has already missed recent defeats to Hibernian and St Johnstone as a result of back spasms and will play no part as the Scottish Communities League Cup finalists meet for a dress rehearsal of their March 17 Hampden decider in Paisley.
The only other absences for Danny Lennon's team are long-term injury victims Darren McGregor (knee) and Thomas Reilly (ankle).
Provisional squad for St Mirren: Samson, Van Zanten, McAusland, Goodwin, Dummett, Newton, McLean, McGowan, McGinn, Thompson, Goncalves, Adam, Parkin, Barron, Mair, Imrie, Guy, Carey.
Provisional squad for Hearts: MacDonald, Wilson, Webster, Walker, Barr, Mullen, Holt, Tapping, Ngoo, King, Ridgers, Prychynenko, Sutton, Novikovas, McGowan, Taouil, McHattie, Smith, Carrick.
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