Abstract Post-traumatic ruptures of the retinaculum extensorum (RE) to the ankle is rare and behind a tendinous luxation, of a rope effect, tiredness and weakening or loss of strength. We report the observation of a patient aged 35 practicing full contact for 20 years, victim of a sports accident two years before upon a foot kick in the kicking bag during a training session bringing about a rupture of the RE at the ankle. Imagery (echography and MRI) made sure the clinical exam and to call for the diagnosis of the rupture of the lower band of the retinaculum with subluxation of the tendons of the tibialis anterior and of the extensor hellucis longus. The take in charge consisted of a local plasty of the RE. On the relapse (6months), the patient is satisfied with the outcome and taking back to his initial sports activity. Through our observation and a review of the literature, we attempt to review the anatomy of the RE to the ankle and to analyze the causes and the consequences of its rupture as well as the usefulness of the imagery in analyzing its anatomic structure. The rupture of the RE is a rare affection mainly affecting sports persons. They can be unseen and may compromise the sports career of athletes. A meticulous clinical exam and targeting imagery as well as an adequate take in charge allow avoiding this unwanted evolution.