Introduction: Metacarpophalangeal joint (MCPJ) dislocations are common hand injuries, requiring prompt reduction to restore function and prevent long-term complications. In some cases, reduction may be challenging due to a range of factors including soft tissue interposition, volar plate entrapment and sesamoid bone obstruction. The incidence of ‘locked thumb’ or irreducible first MCPJ dislocations due to ulnar sesamoid bone obstruction is well described in the literature, however, sesamoid bones causing difficult reduction of dislocations of the other MCPJ dislocations are more rare. Method: We present a case of a 15 year old male patient who sustained a dorso-ulnar dislocation of the second MCPJ of his dominant hand from a skateboarding accident. Open reduction was performed via a volar incision. Exploration demonstrated a complete volar plate rupture with entrapment of a radial sesamoid bone within the joint space preventing reduction. Results: A literature search demonstrated 4 reported cases of index finger MCPJ dislocation with an associated intra-articular entrapment of a sesamoid bone across 3 publications. Reduction was always performed via an open approach, varied between dorsal and volar approaches. Conclusion: Index finger MCPJ dislocation complicated by intra-articular entrapment of a sesamoid bone is a rare phenomenon that has only been sparsely reported. The presence of a sesamoid bone on plain radiograph combined with a second MCPJ dislocation should always raise the concern of an intra-articular entrapment, and open reduction should be expedited, rather than multiple attempts at closed reduction.