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Table 3 CORs flexion/extension for the respective intervals ME-IE, IE-N, N-IF and IF-MF compared to the COR for maximum flexion/extension

From: Cervical disc prostheses need a variable center of rotation for flexion / extension below disc level, plus a separate COR for lateral bending above disc level to more closely replicate in-vivo motion: MRI-based biomechanical in-vivo study

Level

COR

x

y

ME-IE

IE-N

N-IF

IF-MF

ME-MF

ME-IE

IE-N

N-IF

IF-MF

ME-MF

C 3/4

mean

8.1

1.4

−4.2

5.0

4.8

0.8

−4.2

−10.4

−1.9

−5.8

SD

9.1

3.1

13.6

7.4

2.3

13.4

2.5

9.4

7.9

5.6

P

0.251

0.005

0.066

0.949

 

0.131

0.337

0.187

0.755

 

C 4/5

mean

5.3

1.8

−0.2

6.0

4.8

1.0

−4.4

−7.0

−5.3

−3.8

SD

12.5

4.7

8.2

11.5

2.3

11.0

9.0

5.0

15.1

3.7

P

0.901

0.049

0.040

0.728

 

0.212

0.842

0.067

0.788

 

C 5/6

mean

9.4

4.7

1.1

10.7

4.8

−3.4

−3.2

−7.5

−1.3

−4.0

SD

5.9

4.7

5.4

13.6

2.8

8.2

2.8

4.9

6.4

3.1

P

0.026

0.948

0.035

0.163

 

0.792

0.486

0.034

0.243

 

C 6/7

mean

5.5

−0.3

6.8

8.9

4.9

−6.0

−6.9

0.3

−8.0

−1.1

SD

7.5

9.2

3.3

15.3

3.2

11.6

8.4

8.8

6.9

2.6

p

0.845

0.074

0.125

0.430

 

0.314

0.033

0.573

0.404

 
  1. ME maximum extension, IE intermediate extension, N neutral, IF intermediate flexion, MF maximum flexion