The 33-year-old sustained the problem with some fine retrieving to deny Albert Adomah after just 25 minutes and is set for a scan on Thursday.
Early suggestions are that the injury is not too serious, though he is expected to miss the next two games against Derby and Ipswich, with the hope of returning after the international break.
The injury comes at a cruel time for Rotherham-born Richardson, who has been enjoying his best run of form for the club, having started all six games under Neil Warnock.
Another player missing from the side to face the Rams on Saturday is Greg Halford as he sits out a one-match ban.
Halford was dismissed for two yellow cards in the win against Boro - a decision which left Warnock raging.
He said: "I was disappointed Greg got sent off, the first booking I thought was a disgrace really.
"The lad has put it around him, slipped and gone down, the referee is looking.
"I said to him 'You're not even going to give a free-kick', he's looking away and then the linesman flags for England in the corner and they get a booking for it.
"Yet, Greg Halford gets pulled back on the halfway line and he doesn't even get a booking. We're near the bottom of the league, we deserve consistency and we aren't getting it at the minute.
"It's bloody hard work in the Championship, never mind having decisions like that go against us.
"Apart from that I am quite happy."
