A Manhattan woman entered a nursing facility to be treated for rheumatoid arthritis — and was turned into a rambling zombie, her son says in a lawsuit.

Vicky Ortiz, 71, had entered the Fort Tryon Center for Rehabilitation and Nursing in Fort Washington in the past for physical therapy without incident, the suit says. So her son, Hector Ortiz, said he was shocked when he saw her last month.

“I go into her room, and I find her completely naked,” Hector recalled in an interview with The Post.

“She was completely zonked out of her mind.”

Hector said he later got a call from the center saying, “Your mom is walking the hallways incoherently.”

“These are the sort of deplorable conditions you would expect to see in the third world,” said the family’s lawyer, Lowell Sidney.

A rep for the facility said no one was available to comment.