Biomechanical testing of a unique built-in expandable anterior spinal internal fixation system

Table 1 Spinal range of motion of the 3 fixation systems

ROM (°)	Status	Expandable device (n = 6)	Z-plate (n = 6)	Kaneda (n = 6)	p
Flexion	Normal	9.64 (0.81)	9.98 (1.34)	9.49 (0.94)	0.717
	Injury	17.73 (3.67)^a	19.02 (3.12)^a	19.18 (3.21)^a	0.718
	Internal fixation	5.72 (0.44)^ab	5.70 (0.50)^ab	5.63 (0.65)^ab	0.957
Extension	Normal	8.45 (0.52)	8.45 (0.43)	8.48 (0.44)	0.994
	Injury	13.51 (2.21)^a	13.50 (2.53)^a	13.43 (2.25)^a	0.998
	Internal fixation	5.25 (0.28)^ab	5.14 (0.31)^ab	5.12 (0.19)^ab	0.671
Left bending	Normal	8.71 (0.30)	8.78 (0.27)	8.55 (0.41)	0.484
	Injury	18.07 (3.66)^a	18.23 (3.81)^a	18.87 (4.22)^a	0.932
	Internal fixation	5.50 (0.21)^ab	5.37 (0.21)^ab	5.04 (0.13)*†^ab	0.002
Right bending	Normal	8.35 (0.37)	8.47 (0.42)	8.43 (0.39)	0.869
	Injury	18.45 (3.72)^a	18.69 (3.80)^a	19.05 (2.54)^a	0.955
	Internal fixation	5.01 (0.12)^ab	5.05 (0.14)^ab	5.04 (0.11)^ab	0.887
Left axial rotation	Normal	7.11 (0.40)	6.97 (0.34)	7.07 (0.28)	0.769
	Injury	19.56 (2.98)^a	19.05 (3.22)^a	19.04 (3.26)^a	0.948
	Internal fixation	4.53 (0.42)^ab	5.23 (0.30)*^ab	5.02 (0.15)*^ab	0.005
Right axial rotation	Normal	6.95 (0.35)	6.91 (0.31)	6.84 (0.44)	0.883
	Injury	19.60 (3.18)^a	18.65 (3.41)^a	19.41 (3.35)a	0.873
	Internal fixation	4.49 (0.47)^ab	5.23 (0.20)*^ab	5.08 (0.17)*^ab	0.002

ROM, range of motion.
Data are presented by mean and standard deviation.
*Indicates a significant difference compared to the expandable device group.
†Indicates a significant difference compared to the Z-Plate group.
^aIndicates a significant difference compared to the normal state within a group (all, p <0.001).
^bIndicates a significant difference compared to the injured state within group (all, p <0.001).

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