Inducing thoracolumbar burst fractures in human cadaveric specimens using a combined axial-flexion loading: a fracture simulation.

Abstract

Thoracolumbar burst fractures with morphological characteristics in human cadaveric specimens are essential for surgical training and biomechanical research. This study aimed to develop a technique for simulating thoracolumbar burst fractures and to evaluate their consistency of fracture patterns. Six fresh-frozen human thoracolumbar spine segments (Th12-L5) were fractured using a custom-made drop-test bench. Specimens were potted at the cranial and caudal endplates, leaving a central vertebral body exposed to a standardized combined axial-flexion loading applied via a 10° wedge block. Pre- and post-fracture radiographs and computed tomography scans were obtained. Bone quality was assessed using Hounsfield units. In two specimens, fracture initiation and propagation were recorded using high-speed video imaging at 5400 frames per second. Fractures were classified according to the AO Spine Thoracolumbar Injury Classification System. Thoracolumbar burst fractures were successfully generated in all specimens. Two incomplete burst fractures (AO Type A3) and four complete burst fractures (AO Type A4) were produced. Retropulsion of bony fragments into the spinal canal occurred in four specimens. High-speed video analysis demonstrated a consistent two-step mechanism, consisting of initial anterior collapse followed by posterior wall failure. Interobserver agreement for fracture classification was excellent (κ = 1.0). A high-energy combined axial-flexion loading induces consistent thoracolumbar burst fracture patterns in human cadaveric specimens. This experimental model provides a robust platform for biomechanical testing and advanced surgical training. III.