Kyphotic Angle of the Motion Segment Most Accurately Predicts Injury to the Ligamentous Complex on Computed Tomography Scan of Thoracolumbar Fractures

Abstract

To define radiologic parameters and the diagnostic accuracy of computed tomography (CT) scan on posterior ligamentous complex (PLC) injury, identified by magnetic resonance imaging (MRI) in patients with thoracolumbar (TL) fracture. We retrospectively analyzed 88 patients with TL fractures divided into 2 groups by PLC status evident on MRI: intact and ruptured. The parameters assessed included the anterior fractured vertebral body height (AVH) and posterior fractured vertebral body height, upper and lower AVH, anterior/posterior vertebral height ratio, AVH ratio, local kyphotic angle (LKA), region angle (RA), sagittal index (SI), Gardner angle (GA), Gardner index (GI), Cobb angle, interspinous distance (ISD), upper and lower ISD, ISD ratio, interspinous distance minus (ISDM), interspinous angle (ISA), and upper and lower ISA. The t test, Pearson χ2 test, and multivariate logistic regression were used. PLC rupture (vs. intact) was associated with RA, GA, GI, ISD, ISD ratio, and ISDM. The positive risk factors for PLC rupture were GA, LKA, SI, and RA. The negative risk factors for PLC rupture were SI greater than 20° and GI. PLC rupture was associated with the SI, upper interspinous distance, ISD ratio, ISDM, and ISA in those with type A1/A2 fractures and the GA, GI, ISD, ISD ratio, and ISDM in those with type A3/A4 fractures. An RA greater than 16°, SI greater than 20°, and GI greater than 24° were associated with PLC injury in patients with type A TL fractures, and an RA greater than 16° and SI greater than 20° predicted PLC injury in type A1 and A2 fractures. An SI greater than 20°, GI greater than 24°, LKA greater than 26°, and ISD ratio greater than 56% predicted PLC injury in type A3 and A4 fractures.