Shumpert appeared to suffer the injury following a collision with Boston's Jeff Green.
"He was in pain but the first thing he said was go get this win," Knicks coach Derek Fisher said.
Shumpert will have an MRI on Saturday but there is no timetable for his return at this point.
"We don't want to jeopardize the remaining part of his season, so we'll have to see," Fisher said.
Shumpert has started every game he has suited up for this season. With Shumpert out for an indefinite period of time and guard J.R. Smith out with a bruised heel, the Knicks likely will rely heavily on guard Tim Hardaway Jr. to fill in at shooting guard.
Shumpert was averaging 9.5 points per game on 40 percent shooting entering play Friday. He was playing 26 minutes per night for New York, which had lost 10 straight games entering Friday.