Artificial disc and vertebra system: a novel motion preservation
                    device for cervical spinal disease after vertebral corpectomy

Dong, Jun; Lu, Meng; Lu, Teng; Liang, Baobao; Xu, Junkui; Qin, Jie; Cai, Xuan; Huang, Sihua; Wang, Dong; Li, Haopeng; He, Xijing

doi:10.6061/clinics/2015(07)06

Jun Dong

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Meng Lu

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Teng Lu

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Baobao Liang

Second Affiliated Hospital of Xi’an Jiaotong University, Department of Plastic Surgery, Xi’an, China.

Junkui Xu

Xi’an Honghui Hospital of Xiʹan Jiaotong University, Department of Orthopedics, Xi’an, China.

Jie Qin

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Xuan Cai

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Sihua Huang

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Dong Wang

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Haopeng Li

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

Xijing He ^*Corresponding Author: E-mail: xijingh@sina.cn

Second Affiliated Hospital of Xiʹan Jiaotong University, Second Department of Orthopedics, Xiʹan, China.

He X conceived the study. Dong J, Lu M, Liang B and Xu J performed the study and the statistical analysis. Lu T, Qin J and Cai X provided the material and analysis tools. Huang S, Wang D and Li H participated in checking and analyzing the data. Dong J, Lu M, He X and Wang D participated in drafting the manuscript.

Corresponding Author: E-mail: xijingh@sina.cn

Figures (2)
Tables (3)

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Figure 1
The ADVS is made of a titanium alloy (Ti6Al4V), which has three major parts, two discs and a vertebra. There is a hemisphere socket joint between the disc and vertebra that theoretically allow 12° in flexion, extension and lateral bending, 360° in axial rotation. A) ADVS in flexion; B) ADVS in extension; C) the artificial vertebra part; D) the artificial disc part; E) the lateral view of ADVS. 1) the base part of disc, it has a smooth surface on the top that fits the adjacent vertebra; 2) the front wing part; 3) the articular fossa; 4) bone graft tubes in different diameter; 5) the articular head; 6) the “L” structure, which was designed for dislocation between the disc part and the vertebra part; 7) the self-drilling trapping screw; F) upper, middle and lower sagittal diameters of C5 vertebra; G) anterior, media and posterior height from C4∼5 disc to C5∼6 disc. The ADVS was implanted after corpectomy was performed at C5 level, X-ray films of posteroanterior view H) and lateral I) views. The anterior plate fusion performed after cervical discectomy and vertebral corpectomy of C5 level, X-ray films of posteroanterior view J) and lateral K) views.

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Figure 2
ROM of C3∼C7, C3∼4, C4∼6, C6∼7. The ROM were measured under 2 N·m torque loading pressure. A) the fusion group showed a significantly restricted ROM of C3∼C7 regarding flexion, extension and axial rotation ROM of C3∼C7 compared to the intact group and non-fusion group. No significant difference of ROM in any direction was detected when compared the intact group and non-fusion group. B) the fusion group and non-fusion group showed a significantly increased ROM of C3∼4 regarding extension and lateral bending ROM of C3∼4 compared to the intact group. Significant difference of ROM of C3∼4 in axial rotation was detected when compared the intact group and non-fusion group. C) the fusion group showed a significantly restricted ROM of C4∼6 in all directions compared to the intact group and non-fusion group. Comparing with the intact group, the extension and lateral bending ROM of C4∼6 in non-fusion group increased significantly. D) the fusion group showed a significantly restricted ROM of C6∼7 in extension compared to the intact group and non-fusion group. The axial rotation ROM of C6∼7 in non-fusion group decreased significantly comparing with the fusion group. No significant difference of ROM of C6∼7 in any direction was detected when compared the intact group and non-fusion group. *p<0.05

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Table 1
₅ Vertebrae and C_4-5 and C_5-6 Disc Measurements (mm).

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Table 2
Range of Motion of the Specimens in the Intact, Non-Fusion and Fusion Groups in Response to the Maximum Applied Moment of 2 N·m (in degrees).

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Table 3
Index of the Flexibility Test.

Variable		Measured Values	̄ ±s
Sagittal diameter of C₅ vertebrae
	Upper	11.6-17.1	14.24±1.21
	Middle	13.1-18.9	15.6±1.34
Lower	14.2-19.4	16.63±1.22
Height between C_4-5 and C_5-6 discs
	Anterior	21.4-23.7	22.73±0.51
	Middle	23.2-25.4	24.45±0.54
Posterior	18.8-20.6	19.98±0.58

Motion (mean±SD)	ROM of C₃-C₇			ROM of C_3-4			ROM of C_4-6			ROM of C_6-7
Motion (mean±SD)		INT	NF	FU	INT	NF	FU	INT	NF	FU	INT	NF	FU
FLE	13.41±2.09	13.84±1.40^b b Significantly different from the fusion group (p<0.05).	9.63±1.74^a a Significantly different from the intact group (p<0.05).	3.34±1.13	4.20±0.82	4.68±0.92	5.99±1.22	4.72±1.04^b b Significantly different from the fusion group (p<0.05).	0.79±0.29^a a Significantly different from the intact group (p<0.05).	3.39±0.90	3.36±0.41	3.88±0.58
EXT	14.66±1.69	14.16±2.07^b b Significantly different from the fusion group (p<0.05).	11.21±1.68^a a Significantly different from the intact group (p<0.05).	1.92±0.80	3.52±0.73^a a Significantly different from the intact group (p<0.05).	2.96±0.44^a a Significantly different from the intact group (p<0.05).	7.83±1.22	9.88±1.74^{a b} a Significantly different from the intact group (p<0.05).	1.57±0.73^a a Significantly different from the intact group (p<0.05).	4.29±0.81	4.05±0.56^b b Significantly different from the fusion group (p<0.05).	6.14±1.06^a a Significantly different from the intact group (p<0.05).
LB	26.47±5.06	28.87±5.85	24.20±3.00	5.27±1.83	7.72±1.51^a a Significantly different from the intact group (p<0.05).	7.64±0.95^a a Significantly different from the intact group (p<0.05).	12.40±1.79	15.12±1.9^{a b} a Significantly different from the intact group (p<0.05).	6.67±1.03^a a Significantly different from the intact group (p<0.05).	8.35±1.84	7.78±0.84	8.24±1.35
AR	32.40±4.78	35.26±4.16^b b Significantly different from the fusion group (p<0.05).	26.75±1.30^a a Significantly different from the intact group (p<0.05).	7.65±1.58	6.95±0.91^b b Significantly different from the fusion group (p<0.05).	8.00±0.61	25.51±2.91	26.23±2.91^b b Significantly different from the fusion group (p<0.05).	6.63±1.39^a a Significantly different from the intact group (p<0.05).	20.80±3.61	19.34±1.47^b b Significantly different from the fusion group (p<0.05).	22.37±2.49

Motion	Average SI-ROM of C_3-7		Average SI-ROM of C_3-4		Average SI-ROM of C_4-6		Average SI-ROM of C_6-7
Motion		NF	FU	NF	FU	NF	FU	NF	FU
FLE	0.020±0.16	0.20±0.22	-0.40±0.57	-0.52±0.57	0.17±0.33^a a Significantly different from the fusion group (p<0.05).	0.86±0.068	-0.040±0.24	-0.23±0.45
EXT	0.077±0.17	0.18±0.18	-1.13±0.98	-0.81±0.79	-0.31±0.43^a a Significantly different from the fusion group (p<0.05).	0.80±0.088	0.039±0.17^a a Significantly different from the fusion group (p<0.05).	-0.45±0.23
LB	-0.031±0.14	0.0022±0.18	-0.63±0.64	-0.60±0.60	-0.25±0.30^a a Significantly different from the fusion group (p<0.05).	0.45±0.11	0.035±0.22	-0.020±0.23
AR	-0.0081±0.10	0.087±0.11	0.064±0.21	-0.073±0.16	-0.03±0.074^a a Significantly different from the fusion group (p<0.05).	0.74±0.063	0.047±0.17	-0.12±0.32

[1] He X conceived the study. Dong J, Lu M, Liang B and Xu J performed the study and the statistical analysis. Lu T, Qin J and Cai X provided the material and analysis tools. Huang S, Wang D and Li H participated in checking and analyzing the data. Dong J, Lu M, He X and Wang D participated in drafting the manuscript.

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Artificial disc and vertebra system: a novel motion preservation device for cervical spinal disease after vertebral corpectomy

OBJECTIVE:

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CONCLUSION: