The Posterior Ligamentous Complex: Anatomic and Biomechanical Considerations in Injury Classification and Management

The posterior ligamentous complex (PLC) provides critical structural support in the thoracolumbar spine. Its role in resisting progressive flexion is particularly important at the thoracolumbar junction due to the transition from the rigid thoracic spine to the more mobile lumbar region. Each component of the PLC contains anatomic features that contribute to both the structure and function of the PLC as a whole. Understanding the nuances of each structure is important in determining injury severity and may serve as a foundation for future directions of research. Violation of the PLC results in an unstable spine, thus requiring surgical management. It is associated with greater injury severity and neurologic deficit in patients who sustain thoracolumbar fractures, which adds complexity to the postoperative course and patient outcomes. Although plain radiographs and CT scans provide reliable indirect measures of PLC disruption, these modalities may be subject to diminished sensitivity based on patient positioning and do not directly measure soft-tissue injury. Modern classification systems include the integrity of the PLC in surgical decision making, and care must be taken to scrutinize the possibility of ligamentous disruption before proceeding with nonsurgical management to avoid adverse patient outcomes.