Table 2.

Results of meta-analyses calculating the difference in range of motion of intact spinal segments and after ball-and-socket total disc replacement of each spinal segment, motion direction and device using spine simulators with cadavers (SSCs). CAD Charité artificial disc, bsTDR ball-and-socket total disc replacement, AbsTDR all bsTDR (activL, CAD, InOrbit, Maverick, NewPro, Prodisc-L, prototype of an artificial disc in development, Slide-Disc, Triumph), CROM change in range of motion in degree, CI confidence interval (l lower and u upper limit), n number of studies, reference no. reference number.

SSCs		L3/4					L4/5					L5/S1
		overall sagittal motion	extension	flexion	lateral bending	axial rotation	overall sagittal motion	extension	flexion	lateral bending	axial rotation	overall sagittal motion	extension	flexion	lateral bending	axial rotation
CAD	CROM	5.27			1.47	2.01	0.82			2.19	1.21	1.05				0.75
	CI 95% l	3.22			0.32	1.49	−2.04			1.2	0.7	−1.43				−0.06
	CI 95% u	7.32			2.61	2.54	3.69			3.18	1.72	3.54				1.56
	p-value	<0.00001			0.012	<0.00001	0.57			0.000014	<0.00001	0.41				0.069
	Chi2	2.22			1.58	0.26	3.57			17.63	6.54	1.37				0.71
	I2	55%			36.8%	0%	72%			94.3%	84.7%	0%				0%
	n	2			2	2	2			2	2	3				2
	reference no.	[2], [30]			[2], [30]	[2], [30]	[3], [24]			[3], [24]	[3], [24]	[13], [17], [27]				[17], [27]
Maverick	CROM						2.06	1.26	−0.38	−1.31	−0.03	−1.07	2.7	−3.86	−0.22	0.36
	CI 95% l						0.09	0.42	−1.81	−2.29	−0.59	−2.27	2.04	−4.41	−0.61	0.1
	CI 95% u						4.04	2.11	1.06	−0.32	0.54	0.14	3.35	−3.31	0.16	0.63
	p-value						0.04	0.0033	0.6	0.0095	0.93	0.083	<0.00001	<0.00001	0.25	0.0072
	Chi2						2.41	4.9	8.6	14.22	1.01	4.9	0.94	14.26	23.13	4.54
	I2						0%	59.1%	76.7%	78.9%	0%	59.2%	0%	86.0%	91.4%	56%
	n						4	3	3	4	3	3	3	3	3	3
	reference no.						[10], [21], [22], [28]	[21], [22], [28]	[21], [22], [28]	[10], [21], [22], [28]	[10], [21], [28]	[17], [18], [31]	[17], [18], [31]	[17], [18], [31]	[17], [18], [31]	[17], [18], [31]
Prodisc-L	CROM						−0.8			−1.58	0.17	−0.64	1.37	−2.52	0.07	0.08
	CI 95% l						−1.88			−2.14	−0.15	−2.1	0.18	−3.71	−0.43	−0.32
	CI 95% u						0.28			−1.02	0.49	0.81	2.55	−1.33	0.57	0.48
	p-value						0.15			<0.00001	0.31	0.39	0.024	0.000032	0.79	0.7
	Chi2						0.72			6.43	12.82	0.59	0.61	0.07	10.48	5.84
	I2						0%			68.9%	84.4%	0%	0%	0%	71.4%	48.6%
	n						3			3	3	4	2	2	4	4
	reference no.						[16], [19], [29]			[16], [19], [29]	[16], [19], [29]	[15], [17], [26], [31]	[17], [31]	[17], [31]	[15], [17], [26], [31]	[15], [17], [26], [31]
AbsTRD	CROM	5.28			1.01	1.62	−0.8	−0.24	0.69	−0.35	0.36	−0.76	2.49	−3.61	−0.23	0.2
	CI 95% l	3.41			0	1.18	−1.54	−0.67	−0.19	−0.72	0.14	−1.57	1.91	−4.12	−0.53	−0.02
	CI 95% u	7.16			2.02	2.05	−0.06	0.18	1.56	0.03	0.57	0.06	3.08	−3.09	0.06	0.43
	p-value	<0.00001			0.05	<0.00001	0.034	0.26	0.12	0.07	0.0012	0.068	<0.00001	<0.00001	0.12	0.078
	Chi2	2.07			0.47	0	51.84	27.27	14.95	83.94	29.98	7.37	1.2	19.22	55.3	13.69
	I2	51.8%			0%	0%	80.7%	81.7%	66.5%	88.1%	70%	5%	0%	89.6%	91%	56.2%
	n	2			2	2	11	6	6	11	10	8	3	3	6	7
	reference no.	[2], [30]			[2], [30]	[2], [30]	[3], [10], [16], [19], [20], [21], [22], [23], [24], [25], [28]	[16], [20], [21], [22], [24], [28]	[16], [20], [21], [22], [24], [28]	[3], [10], [16], [19], [20], [21], [22], [23], [24], [25], [28]	[3], [10], [16], [19], [20], [21], [23], [24], [25], [28]	[13], [15], [17], [18], [26], [27], [29], [31]	[17], [18], [31]	[17], [18], [31]	[15], [17], [18], [26], [29], [31]	[15], [17], [18], [26], [27], [29], [31]