A flatfooted Rikers Island inmate should be able to sue the city for $6 million after prison officials confiscated his orthopedic shoes, a Manhattan judge has ruled.

In a ruling released Tuesday, Justice Kathryn Freed called city attorneys’ attempt to dismiss the “cruel and inhuman treatment’’ lawsuit “grossly unjust.”

Anthony Toxey, a 64-year-old convicted armed robber, suffers from fallen arches, or flat feet, according to his 2010 suit.

A city Law Department spokeswoman said, “We are reviewing the decision and considering our options.”