I suspect the bindings were nailed to the wall, not the wrists. Poor writing. There’s no mention in the story of him having actual holes in his arms.
http://www.jacksonville.com/tu-online/stories/112107/met_219337187.shtml
In interviews with Baker County detectives, each woman said the other had tied the boy up for hours, kicked him in the stomach and kept him from attending school so teachers would not see his injuries.
Both said the boy was tied by shoelaces to nails in the wall at the residence Martin and Stevenson shared at the Trail Ridge Mobile Home Park.
Dobson said the boy told of being left inside a windowless room for days where he had to defecate and urinate in the small space.
Earlier this year, a day-care center where the boy was taken called Stevenson because he was stealing food, Dobson said.
“We know now he was stealing food because he was hungry,” the sheriff said.