Posterior cruciate ligament avulsion fracture from its tibial insertion is a rare pathology in children. It is usually caused by high-energy traumas and its diagnosis is not always easy. Late diagnosis leads to late treatment, which can result in suboptimal results. We present a case of a 13-year-old boy hit by a car, who had a delay in diagnosis and treatment because of severe head trauma. The patient was treated 4 months after the trauma with open reduction and internal fixation of the avulsion fracture. After 4 years of follow-up, he has no complaints and has achieved good functional outcome.