The convictions of three men who allegedly beat up a nurse on the Upper West Side were tossed by an appeals court on a technicality Tuesday.

Manhattan Justice Judith Gische said Thomas Cruz, Kareem Santiago and Dimitri Marshall should get a new trial because cops didn’t follow strict procedure to properly identify them.

But in his dissent, Justice Peter Tom described how the trio grabbed the 55-year-old woman on 90th Street at Amsterdam Avenue as she headed home from work.

They punched her in the face, knocked her to the ground and kicked her, dislocating her jaw, Tom wrote.