In France, more than 110.000 patients are hospitalized for stroke per year. It is the leading cause of sudden disabilities in adults. Incidence of spastic foot is evaluated at 1 year post stroke from 18% to 56% of hemiplegic patients. Spasticity, defined as an increase in the velocity-dependent response to muscle stretch measured at rest, is part of the upper motor neuron syndrome and is characterized by an increase in tonic stretch reflex. It has been proposed that upper motor neuro syndrome may induce not only spasticity but also other types of muscles overactivity such as spastic dystonia, co-contraction and clonus. In hemiplegic patients, lower limb spasticity within the posterior part of the leg frequently results in equino-varus foot and toes claw. These abnormal postures in hemiplegics may affect activities of daily living such as shoes fitting, balance, ambulation-walking, comfort (pain) and may become irreducible (tendon shortening) if not treated. The purpose of this study is to compare the interest of each treatment (BoNT-A versus STN) in order to specify both techniques indications and up-date current guidelines of lower-limb spasticity for hemiplegic patients. This study aims to confirm a greater reduction of calf muscles spasticity after STN as compared to BoNT-A, as observed in the only published monocentric randomized controlled trial. Our study originality is to perform a multi-center RCT with a pre-established sample size. This study will also quantify progress towards personal goals using the goal attainment scaling (GAS) and will assess other components related to the consequences of carve muscle spasticity on balance, ambulation, self-care and quality of life.