It's a £2.7m bit of artwork designed by sculptor Anish Kapoor, called 'Temenos', and is planned to be one of 5 giant bits of art on the Tees Valley. Any similarity to a giant ankle support, or indeed a Slinky, is purely coincidental. The other possible inspiration could be a giant pair of handcuffs.
If it was informed cultural commentary you were after, try here.
'Temenos' is a Greek word meaning a piece of land set aside for the worship of pagan gods. Maybe the Angel will be wanting his halo back. And his frisbee.