Table 1.

Vertebral translation at normal levels (data from literature), untreated levels (below or above treated levels), mobile-core implanted levels and fixed-core implanted levels

	Normal levels	Untreated levels	Mobile-core implanted levels	Fixed-core implanted levels	Differences between each group*
L3L4	−1.22 ± 0.60 n = 58	−1.29 ± 1.02 n = 46			N versus U	NS
L4L5	−1.03 ± 0.48	−1.20 ± 1.28	−1.10 ± 0.59	−1.74 ± 0.71	N versus U	NS
	n = 49	n = 29	n = 21	n = 15	N versus M	NS
					N versus F	p < 0.001
					U versus M	NS
					U versus F	NS p = 0.08
					M versus F	p < 0.001
L5S1	+0.03 ± 0.97	+1.07 ± 1.61	−0.79 ± 0.44	−1.61 ± 0.4	N versus U	p = 0.02
	n = 37	n = 17	n = 35	n = 18	N versus M	p < 0.001
					N versus F	p < 0.001
					U versus M	p < 0.001
					U versus F	p < 0.001
					M versus F	p < 0.001
L4L5 versus L5S1					ML4L5 versus ML5S1	p = 0.002
					FL4L5 versus FL5S1	NS

n number of cases available, N normal levels, U untreated levels, M mobile-core implanted levels, F fixed-core implanted levels, NS not significant (p > 0.05)

* The Wilcoxon test was used to compare U and M and F. The Student test was used to compare N to all the other levels. Vertebral translation is expressed in millimeter for 10° of range of motion. Means ± standard deviation are shown