Table 1 The demographic data of the subgroups

Long screws

Short screws

P

Long screws

Short screws

P

Long screws

Short screws

P

Number of patients

36

29

-

22

18

-

14

11

-

Gender (male/female)

15/21

13/16

0.798

9/13

9/9

0.565

6/8

4/7

1.000

Age

48.42 ± 13.32

49.31 ± 10.71

0.771

48.00 ± 13.69

46.56 ± 12.06

0.728

49.07 ± 13.19

53.82 ± 6.16

0.283

BMD

− 1.83 ± 1.23

− 1.98 ± 1.09

0.592

− 1.83 ± 1.29

− 1.64 ± 1.17

0.635

− 1.82 ± 1.19

− 2.55 ± 0.68

0.085

Operation segments

 L1-L3

22

15

0.447

14

11

0.870

8

4

0.302

 L2-L4

9

8

0.814

7

3

0.464

2

5

0.177

 L3-L5

5

6

0.467

1

4

0.155

4

2

0.661

 Follow-up

19.31 ± 4.19

19.90 ± 4.13

0.572

19.09 ± 4.49

19.22 ± 4.18

0.925

19.64 ± 3.82

21.00 ± 3.97

0.395

6 screws

4 screws

P

6 screws

4 screws

P

6 screws

4 screws

P

Number of patients

40

25

-

22

14

-

18

11

-

Gender (male/female)

18/22

10/15

0.692

9/13

6/8

0.908

9/9

4/7

0.702

Age

47.35 ± 12.84

51.16 ± 10.76

0.221

48.00 ± 13.69

49.07 ± 13.19

0.818

46.56 ± 12.06

53.82 ± 6.16

0.076

BMD

− 1.74 ± 1.22

− 2.14 ± 1.05

0.184

− 1.83 ± 1.29

− 1.82 ± 1.19

0.989

− 1.64 ± 1.17

− 2.55 ± 0.68

0.027

Operation segments

 L1-L3

25

12

0.251

14

8

0.697

11

4

0.196

 L2-L4

10

7

0.789

7

2

0.432

3

5

0.197

 L3-L5

5

6

0.311

1

4

0.064

4

2

1.000

 Follow-up

19.15 ± 4.30

20.24 ± 3.87

0.306

19.09 ± 4.49

19.64 ± 3.82

0.706

19.22 ± 4.18

21.00 ± 3.97

0.268