Background <p>Pure Posteromedial tibiotalar dislocation unaccompanied by fractures represents an exceptionally rare orthopedic injury, accounting for approximately 0.065% of ankle injuries and 0.46% of ankle dislocations. Such injuries typically result from high-energy trauma, with limited reports involving low-energy mechanisms in athletic activities. This case illustrates the successful management of a closed posterior ankle dislocation in a young student, emphasizing the importance of prompt intervention and structured rehabilitation.</p> Case presentation <p>A 17-year-old male student sustained a pure posterior tibiotalar dislocation during a recreational basketball game, following a forced inversion and plantarflexion mechanism. Immediate closed reduction was performed under local anesthesia combined with intravenous analgesia, followed by immobilization in a splint and subsequent transition to a controlled ankle motion (CAM) boot. Post-reduction CT confirmed anatomical reduction and excluded occult fracture, while CTA showed no evidence of vascular injury; serial clinical examinations revealed no sensory or motor deficit. At one-year follow-up, the patient achieved a full functional recovery and unrestricted return to academic and physical activities.</p> Conclusion <p>This case underscores that early closed reduction and phased rehabilitation can yield excellent outcomes in pure posteromedial tibiotalar dislocation, even in adolescent populations. The report highlights the viability of non-operative management for such injuries and contributes to the sparse literature on low-energy mechanisms in young, non-professional athletes.</p>