BACKGROUND: Management of avulsion fractures in the upper cervical spine remains the subject of debate. Currently, most experts favor nonoperative management of an isolated injury. However, these injuries can be complicated by soft-tissue trauma, which may require a different clinical approach to management. Accurate diagnosis of soft-tissue injuries depends on the choice of imaging modality and consideration of unique patient-specific factors. CASE DESCRIPTION: A morbidly obese 34-year-old woman was involved in a low-velocity motor vehicle collision that caused a forceful extension of the cervical spine. Initial computed tomographic imaging demonstrated a displaced avulsion fracture of the C2 body and widening of the C2-C3 facet. However, subsequent imaging using magnetic resonance demonstrated more extensive injuries. Because bracing was not feasible due to cervical instability, the injury was treated with posterior C2-4 fusion and bone grafting. CONCLUSIONS: Even in low-velocity collisions and limited injury on imaging, patient-specific factors should be considered in management decisions. Magnetic resonance imaging showed significant ligamentous compromise and marked cervical instability, revealing potential damage to vulnerable neural structures. Magnetic resonance imaging should be considered in the initial approach to any patient with these injuries.