Newcastle keeper Krul out for rest of season
The 25-year-old was forced off after an hour of the derby at St James' Park and replaced by Rob Elliott after awkwardly punching away a free-kick from Adam Johnson.
Krul, who has played five times for the Netherlands, had only just returned to the starting line-up after being sidelined for a month with an ankle injury.
Newcastle were trailing 1-0 at the time, but lost after Johnson and David Vaughan added two more to Stephane Sessegnon's opener midway through the first half.
Newcastle manager Alan Pardew said Krul will miss their remaining five league games.
"Tim has dislocated his shoulder and is definitely out for the season," Pardew told reporters.
"The loss of Tim and the goal that was not given for offside were a couple of crucial moments.
"Losing Tim lost me a pair of legs and one sub which was difficult. Those two moments meant Sunderland could see out the win."
The victory was Sunderland's biggest at Newcastle since 1966 and eased their relegation worries.