Table 2 Association between intradiscal vacuum phenomena (VPs) and disc degeneration

Total

I

II

III

IV

V

VP (−)

Count

(% raw)

8

(3.0%)

55 *

(20.6%)

77 *

(28.8%)

99

(37.1%)

28 *

(10.5%)

267

Exp. Count

4.8

34.5

59.3

102.3

66.0

Corrected

P-value

0.02

< 0.0001

< 0.0001

0.51

< 0.0001

Spot

Count(% raw)

0

(0%)

1

(2.6%)

13

(34.2%)

20

(52.6%)

4

(10.5%)

38

Exp. Count

0.7

4.9

8.4

14.6

9.4

Corrected

P-value

0.38

0.05

0.06

0.06

0.03

Linear

Count

(% raw)

0

(0%)

1

(2.2%)

8

(17.8%)

16

(35.6%)

20 *

(44.4%)

45

Exp. Count

0.8

5.8

10.0

17.2

11.1

Count

(% raw)

0.03

0.02

0.45

0.69

0.0012

Island

Count

(% raw)

0

(0%)

0 *

(0%)

0 *

(0%)

34

(37.4%)

57 *

(62.6%)

91

Exp. Count

1.7

11.8

20.2

34.9

22.5

Corrected

P-value

0.15

< 0.0001

< 0.0001

0.83

< 0.0001

Total

I

II

III

IV

V

VP (−)

Count

(% raw)

8

(3.0%)

55 ^#

(20.6%)

77 ^#

(28.8%)

99

(37.1%)

28 ^#

(10.5%)

267

Exp. Count

4.8

34.5

59.3

102.3

66.0

Corrected

P-value

0.02

< 0.0001

< 0.0001

0.51

< 0.0001

A-N

Count

(% raw)

0

(0%)

2

(2.7%)

10

(13.5%)

26

(35.1%)

36 ^#

(48.6%)

74

Exp. Count

1.3

9.6

16.4

28.4

18.3

Corrected

P-value

0.20

0.004

0.45

0.53

< 0.0001

N

Count

(% raw)

0

(0%)

0

(0%)

9

(16.4%)

28

(50.9%)

18

(32.7%)

55

Exp. Count

1.0

7.1

12.2

21.1

13.6

Corrected

P-value

0.28

0.0023

0.26

0.04

0.14

N-P

Count

(% raw)

0

(0%)

0

(0%)

2

(7.1%)

11

(39.3%)

15 ^#

(53.6%)

28

Exp. Count

0.5

3.6

6.2

10.7

6.9

Corrected

P-value

0.46

0.004

0.05

0.91

0.00025

A-N-P

Count

(% raw)

0

(0%)

0

(0%)

0

(0%)

5

(29.4%)

12 ^#

(70.6%)

17

Exp. Count

0.3

2.2

3.8

6.5

4.2

Corrected

P-value

0.2

0.004

0.05

0.53

< 0.0001