A method of manufacturing a curved spinal rod is disclosed. The method includes heating PEEK; injecting the PEEK into an arcuate spinal rod mold; holding the injected PEEK in the mold until the PEEK substantially sets; and removing the injected PEEK from the mold. In another aspect, a spinal rod is disclosed. The spinal rod includes an arcuate main body having a first end portion, a second end portion, and a central portion. The central portion has a non-circular cross-section with a height greater than its width. The first and second end portions and the central portion of the arcuate main body are integrally formed of a polymer such as polyetheretherketone (PEEK). The spinal rod also includes a rounded end cap adapted to mate with at least one of the end portions. The end cap is radiopaque.