Posterior tension band

The posterior tension band is a critical structural component of the spinal column, responsible for maintaining stability during spinal motion, particularly against flexion forces. It consists of the posterior ligamentous complex (PLC) and the posterior bony elements of the spine. Damage or disruption to the posterior tension band is a hallmark of certain spinal injuries, particularly AOSpine thoracolumbar spine injury classification system Subtype B.

The posterior tension band includes:

Posterior Ligamentous Complex (PLC):

Supraspinous ligament: Runs along the tips of the spinous processes. Interspinous ligament: Connects adjacent spinous processes. Ligamentum flavum: Connects the laminae of adjacent vertebrae. Capsular ligaments of the facet joints: Stabilize the zygapophyseal (facet) joints. Posterior Bony Elements:

Spinous processes. Laminae. Pedicles. Function of the Posterior Tension Band Maintains the integrity of spinal alignment, especially during movements that apply flexion forces. Resists distraction forces that could cause separation of the vertebral segments. Provides secondary support to protect the spinal cord and neural elements from excessive motion. Injuries Involving the Posterior Tension Band Disruption of the posterior tension band can occur in various mechanisms, including:

Flexion-distraction injuries: Hyperflexion forces overstretch and rupture the posterior tension band (common in Type B2 injuries). Hyperextension injuries: Tension failure of the posterior elements, often combined with anterior column failure (Type B3 injuries). Pathological conditions: Conditions like ankylosing spondylitis increase the risk of posterior tension band failure due to altered biomechanics. Clinical and Imaging Features of Posterior Tension Band Disruption Clinical signs:

Increased spinal instability. Neurological symptoms if associated with spinal cord or nerve compression. Imaging (CT and MRI):

MRI is the gold standard for evaluating the PLC. Findings include: Disruption or discontinuity of ligaments (supraspinous, interspinous, ligamentum flavum). Facet joint dislocation or widening. Increased interspinous distance on radiographs or CT (indicative of flexion-distraction injury). Associated fractures of the posterior elements. Management Implications Injuries with posterior tension band disruption are typically unstable. Surgical stabilization is often indicated, especially if there is associated: Neurological compromise. Multi-column instability. Underlying conditions like osteoporosis or ankylosing spondylitis. Reconstruction of the posterior tension band with instrumentation (e.g., pedicle screws and rods) and ligament repair or augmentation is commonly performed during surgical stabilization.