In this paper, a new framework for the tracking of closed curves is described. The proposed approach, formalized through an optimal control technique, enables a continuous tracking along an image sequence of a deformable curve. The associated minimization process consists in a forward integration of a dynamical model followed by a backward integration of an adjoint dynamics. This latter pde includes a term related to the discrepancy between the state variables evolution law and discrete noisy measurements of the system. The closed curves are represented through an implicit surface.