A modular screw includes a first assembly and a second assembly. The first assembly includes a base portion having a head portion, a securing portion defining a first bore, and a receiving portion defining a second bore. The second assembly includes a first post, a second post including an engaging portion, and an elongate screw threadably engageable with the second post. The second post is dimensioned to be received through the second bore of the receiving portion of the first assembly such that when a first set screw is received in the first bore, the first set screw secures the base portion of the first assembly to the second post. The elongate screw received in the second post causes radial expansion of the engaging portion of the second post, which, in turn, causes the engaging portion to be affixed to the cavity of the first post.