Table 1 Displacement and rotation of left and right facet joints at different lumbar segments

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0 kg

10 kg

P

0 kg

10 kg

P

0 kg

10 kg

P

Translation

 Left (mm)

  X

1.68 ± 0.86

0.40 ± 0.74

 < 0.01

0.91 ± 1.37

 − 0.74 ± 1.67

0.28

2.19 ± 2.28

 − 0.65 ± 0.69

 < 0.01

  Y

 − 0.78 ± 1.10

 − 0.30 ± 0.65

0.25

 − 0.35 ± 1.77

0.28 ± 0.53

0.30

 − 1.07 ± 0.79

 − 2.45 ± 0.49

 < 0.01

  Z

 − 1.34 ± 2.84

 − 0.97 ± 1.02

0.70

 − 2.12 ± 0.88

 − 1.72 ± 2.30

0.62

0.72 ± 0.81

 − 1.14 ± 1.04

 < 0.01

Translation

 Right (mm)

  X

1.45 ± 0.89

0.69 ± 0.53

0.03

0.62 ± 1.14

 − 0.36 ± 1.09

0.06

2.36 ± 2.37

 − 0.57 ± 0.85

 < 0.01

  Y

0.52 ± 0.47

0.05 ± 0.40

0.03

0.53 ± 0.87

 − 0.13 ± 0.91

0.11

 − 0.86 ± 2.88

 − 0.17 ± 1.10

0.49

  Z

0.49 ± 2.07

0.05 ± 1.75

0.01

1.61 ± 1.00

1.17 ± 1.02

0.35

1.53 ± 0.57

1.35 ± 0.51

0.47

 Rotation Angle (°)

 α

 − 1.41 ± 3.55

 − 1.01 ± 2.64

0.78

 − 0.39 ± 1.52

 − 1.25 ± 2.59

0.37

0.60 ± 2.95

 − 0.56 ± 2.71

0.37

 β

5.67 ± 2.70

2.22 ± 3.70

0.03

7.89 ± 2.59

3.67 ± 5.79

0.05

1.28 ± 2.08

3.98 ± 0.37

 < 0.01

 γ

 − 2.65 ± 2.05

 − 0.57 ± 1.43

0.02

 − 0.85 ± 3.65

0.21 ± 2.14

0.44

0.03 ± 2.02

 − 1.35 ± 1.62

0.11