The juě reading is bound to the colloquial phrase 尥蹶子, a mule or horse jerking its hind legs up and back. It is northern spoken usage and never appears alone.
The foot radical on the left, in its compressed left-side form. It signals an action of the legs and feet, such as stumbling, falling, or kicking. It groups 蹶 with 跌, 踏, and 踢.