2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117193In this work we consider compact binaries on eccentric orbit under the spin-spin interaction. Using the post-Newtonian formalism, the binaries undergo a perturbed Keplerian motion. Here we investigate only the radial motion and derive the contribution of the second post-Newtonian order spin-spin effect to the solution.4 pages, $g_t$ from Kepler equation removed as compared to the published version, in Proceedings of the Astrophysics of Variable StarsAstrophysicstext