Table 5.

Comparison of disc degeneration and posterior longitudinal ligament degeneration.

	Disc degeneration grades (ddg)
PLL degeneration grades (pdg)	0	1	2	Total	P value (pdg, ddg)
0	0	2	0	2	-
1	7	8	8	23	Pa (1, 0)= .003
2	2	19	4	25	Pb (2, 1)=.001, Pc (2, 2)=.001
Total	9	29	12	50	Pd=.002

Data are numbers of patients. Overall chi-square P value: .008, degrees of freedom: 2. Crosstabs with Pearson chi-square test (P^a, P^b, P^c) and dependent-sample t-test (P^d):

^aGrade 1 PLL degeneration was significantly higher than those with grade 2, with non-degenerated (grade 0) discs.

^bGrade 2 PLL degeneration was significantly higher than those with grade 1 and 0, with partial degenerated (grade 1) discs.

^cGrade 2 PLL degeneration was significantly lower than those with grade 1, with severe degenerated (grade 2) discs.

^dPLL degeneration grades were statistically significantly higher compared to disc degeneration grades.