The long-range topological disorder of a screw dislocation provides a peculiar medium for waves in solids. Influences of potential in this medium to electronic states are investigated. A square well potential is employed as a simple example. The potential scattering solution in this medium is successfully obtained in terms of the phase-shift analysis. The unperturbed wave function is not the plane wave but the exact solution of the Aharonov-Bohm equation. The number and position of the bound state levels depend on the coupling of an electron and the topological disorder.