Table 4.

The analysis of risk factors for L4/5 and L5S1 discs

	L4/5				L5S1
	Degeneration	No change		p value	Degeneration	No change		p value
Age (y)	25.60 ± 5.46	22.47 ± 4.42	1.479	0.145	23.00 ± 5.15	22.73 ± 4.55	0.123	0.903
BMI	22.34 ± 1.97	22.86 ± 0.91	− 1.070	0.290	22.69 ± 0.51	22.82 ± 1.08	− 0.257	0.799
Fixed time (m)	17.60 ± 1.97	16.98 ± 6.51	0.202	0.841	15.20 ± 4.97	17.29 ± 6.61	− 0.684	0.497
Vertebral slip (n)	5	49	0.117	0.732	5	49	0.000*	1.000
yes	1	19			2	18
no	4	30			3	31
Facet grade pre-operation	5	49	2.305	0.310			1.870	0.641
Grade 4	0	13			4	7
Grade 3	5	28			7	14
Grade 2	0	8			4	9
Grade 1	0	0			1	8
Grade 0	0	0			0	0
Disc grade pre-operation	5	49	3.094	0.347	5	49	6.854	0.113
Grade 1	2	9			3	10
Grade 2	2	26			0	22
Grade 3	0	10			2	10
Grade 4	1	4			0	6
Grade 5	0	0			0	1

BMI, Body Mass Index

^*Test was considered statistically significant at p < 0.05