Various bone fixation devices and methods of using the same are provided. In one embodiment, a spinal implant assembly is provided having a generally U-shaped rod-receiving head or receiver member, and a bone-engaging member extending distally from the receiver member. The receiver member can have two side arms extending proximally from a distal end, and the arms can define a U-shaped channel therebetween for receiving a spinal fixation element. The side arms of the receiver can have various configurations and can include a number of features to facilitate mating with a spinal tool.
