The full-back, a summer signing from Dagenham, was crocked after coming on as a half-time substitute during Tuesday's Carling Cup win over the Black Cats.
Vincelot will miss Saturday's visit of Peterborough but manager Gus Poyet is hopeful he will not be sidelined for long.
"I'm not sure how long he'll be out for yet," said Poyet.
"I thought he dislocated his elbow on Tuesday night but it's actually his shoulder.
"We'll have to see if there is any ligamant or muscle damage around the shoulder."