The present application is directed to embodiments of a pedicle screw
assembly to position an elongated member within a patient. The assembly
may include a receiver with a channel sized to receive the elongated
member and a chamber. The assembly may also include an anchor with a head
sized to fit within the chamber. The assembly may include a compression
member sized to fit within the chamber and include a first side that
contacts against the head and a second side that contacts against the
receiver. At least one of the receiver, anchor, and compression member
may be constructed of a first material, and at least one of the receiver,
anchor, and compression member may be constructed of a second material.
The first and second materials may include different moduli of elasticity
to prevent deformation of the assembly.