An MRI taken Saturday confirmed the shoulder dislocation. The team said Shumpert will be re-evaluated in three weeks, leaving his timetable to return uncertain.
"We don't want to jeopardize the remaining part of his season, so we'll have to see," Knicks coach Derek Fisher said Friday night, before Shumpert underwent an MRI.
In other injury news, an MRI taken on J.R. Smith's left foot Saturday revealed a small partial tear of the plantar fascia, the team said. Smith is questionable for Sunday's game against the Toronto Raptors and will remain day-to-day after that.
With Shumpert out indefinitely and Smith hobbled, the Knicks likely will rely heavily on guard Tim Hardaway Jr. to fill in at shooting guard.
Shumpert had started all 23 games he suited up for and 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 is 5-20 and snapped a 10-game losing streak with Friday's win.
Smith has missed the last two games due to the foot injury. The prognosis isn't as clear as Smith had hoped it would be.
Smith said Friday that the injury was a simple bone bruise, but the team wanted to take an MRI to ensure that it wasn't more complicated than that.
The timetable for return following plantar fascia injuries varies widely depending on the degree of the tear.
If Smith can't play against Toronto on Sunday, the Knicks may have to use Jose Calderon at shooting guard for some stretches because Hardaway Jr. would be the only healthy traditional shooting guard on the roster.
On the season, Hardaway Jr. is averaging 9.6 points on 41 percent shooting in 18.4 minutes per game.