Inclusion Criteria:  Walking child from 5 to 15 years old. From hour 0 to hour 48 of ankle trauma with torsion mechanism (inversion, eversion or rotation). Patient presenting for the first time to the emergency room for this traumatic episode. Possibility of carrying out an ultrasound during the passage to the emergency room. Child and parents' consent in the study participation  Exclusion Criteria:  Direct shock on the foot without sprain mechanism. Fracture with deformation or open fracture. History of ankle trauma in the last 3 months. Neurological or neuromuscular pathology. Child with a delay in acquisitions and / or psychomotor development (difficulties in understanding and interacting to locate pain). Absence of a representative of parental authority. Constitutional bone disease or connective tissue. Acquired or congenital coagulopathy. Patient presenting beyond 48h of trauma. Polytraumatized. Dermabrasion, wound or sign of skin suffering next to the ankle requiring specific monitoring. Diagnosis after imaging: fracture or sprain of high grade. Child or parents refusal in study participation