Mechanisms of Hyperflexion / Hyperextension Injury Cervical Acceleration – Deceleration (CAD) Injury

Hyperflexion and hyperextension injuries of the cervical spine represent two extremes of motion that can lead to acute and chronic pathology in ligamentous, discal, and capsular structures. These mechanisms often occur during rapid, low-velocity impacts, such as rear-end or frontal collisions, and may present without radiographic evidence of fracture. The absence of radiographic abnormality does not rule out soft-tissue injury. This principle is supported by cadaveric, volunteer, and computational studies demonstrating microfailure at resolutions below imaging limits.11, 13, 27 Understanding the vector forces, tissue failure thresholds, and resultant kinematic disruptions is central to forensic spinal analysis and clinical correlation. This paper examines the biomechanical pathways that lead to these injuries, including soft-tissue trauma. It draws on data from cadaveric studies, volunteer experiments, and finite-element (FE) modeling, and discusses the medicolegal considerations required to determine injury probability within accepted forensic and Rule 702/Daubert reliability frameworks.