Table 3 Measurement values from three radiologists and model estimates for sagittal intervertebral rotational motion (SIRM) (°)

 C2/3

5.07 ± 3.36

6.19 ± 3.32

5.29 ± 3.33

5.52 ± 2.98

5.01 ± 3.29

−3.327

0.001

 C3/4

10.95 ± 4.81

10.46 ± 4.72

10.82 ± 4.61

10.74 ± 4.49

10.78 ± 4.77

0.218

0.827

 C4/5

12.40 ± 5.36

12.56 ± 5.63

12.66 ± 5.35

12.54 ± 5.23

12.68 ± 5.66

0.683

0.496

 C5/6

11.46 ± 6.17

11.39 ± 5.93

11.44 ± 6.10

11.43 ± 5.90

11.21 ± 6.23

−1.028

0.307

 C6/7

9.84 ± 5.18

9.73 ± 5.17

9.85 ± 5.05

9.81 ± 4.95

9.59 ± 5.21

−1.311

0.193

 C2/3

3.71 ± 2.71

4.02 ± 2.64

3.87 ± 2.60

3.87 ± 2.19

3.94 ± 2.64

−0.392

0.696

 C3/4

6.13 ± 3.95

6.36 ± 3.39

6.22 ± 3.89

6.24 ± 3.49

6.79 ± 3.73

−3.118

0.002

 C4/5

6.96 ± 4.08

6.98 ± 4.09

7.20 ± 3.71

7.05 ± 3.69

7.22 ± 4.29

0.748

0.456

 C5/6

7.55 ± 4.28

7.49 ± 4.25

7.47 ± 4.38

7.50 ± 4.08

7.32 ± 4.51

−0.881

0.381

 C6/7

7.86 ± 4.39

7.72 ± 4.15

7.80 ± 4.22

7.79 ± 4.01

7.65 ± 3.93

−0.952

0.344

 C2/3

2.84 ± 2.29

3.00 ± 2.37

2.77 ± 2.07

2.87 ± 1.74

2.69 ± 1.88

−1.095

0.276

 C3/4

5.06 ± 3.80

4.38 ± 3.63

4.76 ± 3.69

4.73 ± 3.47

4.27 ± 3.39

−2.789

0.006

 C4/5

5.91 ± 4.11

5.81 ± 4.05

5.57 ± 3.95

5.76 ± 3.84

5.64 ± 4.04

−0.585

0.560

 C5/6

4.57 ± 3.51

4.25 ± 2.94

4.47 ± 3.25

4.43 ± 2.93

4.65 ± 3.38

1.127

0.262

 C6/7

2.71 ± 2.09

2.62 ± 2.21

2.76 ± 2.36

2.70 ± 1.90

2.72 ± 2.41

0.123

0.902