Experimental Model of Proximal Junctional Fracture after Multilevel Posterior Spinal Instrumentation

Table 1

Loading conditions for all four porcine specimens.

Loading characteristics	Specimen 1	Specimen 2	Specimen 3	Specimen 4
Loading control	Displacement	Force	Force	Displacement
Loading mode	Continuous	Cyclic at 1 Hz	Cyclic at 1 Hz	Continuous
Loading speed and amplitude	25 mm/min	Incremental after every 1000 cycles at 50–200 N, 50–400 N, 50–600 N, 50–800 N, 50–1000 N	Incremental after 150 cycles at 200–800 N, 100 cycles at 200–1300 N, 400 cycles at 200–2500 N, 100 cycles at 200–3500 N	25 mm/min
Loading axis	Anterior vertebral body line	Center vertebral body line	Center vertebral body line	Center vertebral body line
Boundary conditions	Upper: free flexion-extension; Lower: fixed	Upper: free flexion-extension; Lower: fixed	Upper: 0°–15° constrained flexion; Lower: fixed	Upper: 0°–15° constrained flexion; Lower: free anterior-posterior