Sequential damage of posterior ligamentous complex and its clinical significance in patients with thoracolumbar fracture

Abstract

Objective To investigate the damage sequence of posterior ligamentous complex (PLC) and its clinical significance in thoracolumbar fracture. Methods Data of 132 patients with spinal fracture evaluated with X-rays, CT and short-tau inversion-recovery (STIR) sequences in MRI were collected prospectively. Fracture morphology was classified using the AO classification. PLC components including interspinous ligament (ISL), supraspinous ligament (SSL), ligamentum flavum (LF) and facet capsules (FC) were assessed and classified as intact, edema, or tear. ISL edema was further subdivided depending on the extension (>50% or ≤50%). Correlation between MRI signal and AO progressive scale of morphological damage was analyzed. Results AO type A1/A2 fracture associated with only FC distraction. AO type A3 fracture showed additional ISL tear, usually less than 50%, with neither LF nor SSL tear. AO type B1 fracture showed FC distraction, ISL edema or disruption, and low rate of SSL/LF tear, but B2 fracture increased the rate of SSL/LF tear. AO type C fracture showed facet fracture or dislocation and ISL, SSL as well as LF tear. High correlation was found between AO progressive scale and MRI signal(P< 0.01). Conclusions MRI study can well display the PLC damage and damage sequence. MRI correlates with AO progressive scale of morphological damage, which shows a progressive orderly rupture sequence among different PLC components as traumatic forces increase. Key words: Spinal fractures; Magnetic resonance imaging; Posterior ligamentous complex