Posterior Ligamentous Complex (PLC) Integrity

Definition: The Posterior Ligamentous Complex (PLC) refers to a group of ligaments and soft tissues that stabilize the posterior aspect of the spinal column. PLC integrity is critical for maintaining spinal stability, especially after trauma.

Components of the PLC:

• Supraspinous ligament
• Interspinous ligament
• Ligamentum flavum
• Facet joint capsules

Function:

• Provides posterior tension band support to resist flexion, rotation, and shear forces.
• Helps maintain alignment of the vertebrae.
• Prevents instability and progressive deformity after spinal trauma.

Clinical Significance:

• Loss of PLC integrity is a key criterion in the Thoracolumbar Injury Classification and Severity Score (TLICS).
• MRI is the gold standard for assessing PLC injury.
• Disruption may necessitate surgical stabilization even in the absence of neurological deficits or vertebral collapse.

Imaging Findings Suggestive of PLC Injury:

• Increased interspinous distance on X-ray or CT.
• High signal in ligaments on T2/STIR MRI.
• Facet dislocation or widening.
• Kyphotic angulation.

Related Concepts:

• Spinal instability
• Thoracolumbar burst fractures
• Flexion-distraction injuries