Biomechanical Comparison between Isobar and Dynamic-Transitional Optima (DTO) Hybrid Lumbar Fixators: A Lumbosacral Finite Element and Intersegmental Motion Analysis

Table 2

The interpedicular travel (IPT) and interpedicular displacement (ID) of DTO and Isobar at transition segment were evaluated by calculating scale difference.

Load condition	Device	IPT				ID
		(mm)	(mm)		value	(mm)	(mm)		value
Axial load	DTO			1.18	0.28			7	<0.001
	Isobar			0.61	<0.001			0.20	0.02
Axial+flexion	DTO			1.29	0.18			4	0.13
	Isobar			0.87	0.01			0.24	<0.001
Axial+bending (stretching side)	DTO			0.90	0.21			1.57	0.01
	Isobar			0.80	0.01			1.00	0.43
Axial+bending (contraction side)	DTO			0.95	0.36			1.16	0.02
	Isobar			0.50	<0.001			0.27	<0.001

Note: the stiffness of 600 N/mm ( and ) and 1100 N/mm ( and ), respectively, were used to simulate different grades of mild degeneration at L3/4. The stiffness of 1600 N/mm was used to stimulate moderate degeneration at L4/5 for all models in the mean time.