Table 2 Relationship of radiological parameters and S1 screw loosening

 Preoperative

27.8 ± 13.2

28.7 ± 12.1

0.759

 Soon after surgery

11.3 ± 7.3

10.2 ± 5.9

0.460

 Change

−16.5 ± 8.4

−18.5 ± 8.7

0.298

 Final

11.4 ± 6.3

10.3 ± 5.2

0.392

 Preoperative

43.7 ± 44.4

47.2 ± 51.1

0.745

 Soon after surgery

25.0 ± 34.2

14.4 ± 41.0

0.252

 Change

−21.2 ± 57.3

−31.8 ± 57.7

0.456

 Final

46.7 ± 35

54.2 ± 38.2

0.392

 Preoperative

22.4 ± 11.8

24.1 ± 10.5

0.533

 Soon after surgery

17.5 ± 10.3

17.3 ± 8.3

0.923

 Change

−4.4 ± 10.1

−6.8 ± 7.7

0.265

 Final

21.7 ± 10.2

22.6 ± 9.5

0.696

 Preoperative

26.4 ± 15.0

23.0 ± 15.1

0.334

 Soon after surgery

37.7 ± 10.0

36.5 ± 11.0

0.619

 Change

11.3 ± 13.4

13.5 ± 13.3

0.482

 Final

31.9 ± 10.1

30.1 ± 12.7

0.502

 Preoperative PI-LL (°)

20.3 ± 16.4

23.8 ± 17.4

0.372

 Preoperative

20.2 ± 11.8

22.0 ± 11.5

0.503

 Soon after surgery

13.5 ± 8.4

12.6 ± 7.9

0.638

 Change

−6.2 ± 9.8

−9.5 ± 8.2

0.145

 Final

20.1 ± 10.4

21.3 ± 9.2

0.599

 Blood loss (ml)

1244.4 ± 709.9

1294.1 ± 946.5

0.798

 Operative time (min)

278.4 ± 55.2

277.7 ± 63.5

0.960

 Average  hospitalization (days)

13.1 ± 6.8

14.6 ± 9.0

0.425

 ODI score

27.2 ± 21.6

31.6 ± 18.9

0.366