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.