Table 3 Comparison of radiologic parameters

Preoperation

15.50(9.45–17.60), (3.90–20.80)

14.10(5.45–19.55), (3.90–26.40)

0.781

Postoperation

15.80(10.25–17.90), (7.70–27.90)

17.25(8.50–19.10), (3.00–27.30)

0.772

2 years follow-up

15.95(13.45–24.15), (10.20–28.50)

14.65(11.00–29.70), (1.10–45.50)

0.877

2 years follow-up - Preoperation

3.80(0.70–8.50),(− 5.70–17.00)

5.20(− 3.60–15.30),(− 12.20–30.00)

0.984

Preoperation

5.45(4.60–5.95), (1.80–7.10)

4.95(4.00–5.50), (1.30–7.10)

0.215

Postoperation

5.85(2.90–7.45), (0.50–14.40)

5.70(3.45–7.55), (1.00–14.40)

0.918

2 years follow-up

5.90(5.10–7.25), (1.20–9.60)

5.20(3.75–6.10), (0.90–10.00)

0.207

2 years follow-up - Preoperation

0.70(− 0.75–2.90), (− 4.80–5.30)

0.50(− 1.60–2.30), (− 4.80–6.90)

0.643

Preoperation

5.60(5.15–6.18), (4.23–7.90)

5.96(5.58–6.26), (5.18–6.97)

0.173

Postoperation

7.16(6.46–7.90), (5.84–8.91)

7.53(7.27–7.84), (6.52–8.91)

0.117

2 years follow-up

6.22(5.41–6.58), (4.82–13.12)

5.19(5.15–5.55), (5.01–5.82)

< 0.001*

2 years follow-up – Preoperation

0.08(− 0.52–2.02), (− 1.42–6.95)

− 0.44(− 1.15--0.19), (− 1.78–0.45)

0.007*

Preoperation

Postoperation

20.05(15.39–26.31), (12.46–30.53)

19.33(13.92–26.13), (9.77–29.04)

17.06(15.15–24.72), (6.97–28.53)

18.58(13.25–29.88), (6.72–39.25)

0.261

0.877

2 years follow-up

15.78(12.36–21.51), (10.62–30.84)

17.28(11.18–29.57), (4.42–41.93)

0.703

2 years follow-up - Preoperation

−3.98(− 5.80--2.84), (− 9.62–7.01)

− 0.26(− 4.15–5.88), (− 5.32–15.96)

0.005*

Preoperation

30.77(24.05–35.06), (15.71–42.98)

25.68(20.72–29.36), (13.25–55.43)

0.018*

Postoperation

27.65(17.49–28.63), (10.59–52.27)

28.94(17.12–30.42), (4.40–61.23)

0.414

2 years follow-up

24.53(11.82–32.77), (9.37–48.84)

28.56(11.53–41.36), (4.74–77.58)

0.496

2 years follow-up - Preoperation

−1.30(− 3.00–1.25), (− 14.90–2.90)

0.50(− 0.70–2.75), (− 15.40–7.10)

0.066

Preoperation

25.15(20.25–27.90), (12.00–31.60)

24.10(22.00–25.90), (11.90–44.00)

0.687

Postoperation

24.85(17.10–28.10), (13.60–32.80)

25.40(20.50–27.55), (14.80–32.50)

0.599

Last follow-up

23.50(17.60–27.00), (12.00–33.20)

25.80(20.75–28.00), (15.40–49.20)

0.327

Last follow-up - Preoperation

−1.30(− 3.00–1.25), (− 14.90–2.90)

0.50(− 0.70–2.75), (− 15.40–7.10)

0.066

Preoperation

104.65(101.20–108.65), (89.90–115.90)

111.05(107.85–114.70), (101.20–120.00)

< 0.001*

Postoperation

104.75(100.90–108.45), (94.60–117.00)

105.90(103.65–111.45), (95.50–113.60)

0.397

2 years follow-up

105.80(100.60–111.60), (92.80–115.50)

105.80(99.10–107.30), (87.30–121.40)

0.634

2 years follow-up - Preoperation

3.65(−4.50–8.35), (− 13.30–10.70)

−8.15(− 15.15–2.70), (− 20.10–9.80)

0.004*

Subsidence

1 (4%)

8 (33%)

0.023*

Fusion

22 (92%)

22 (92%)

0.999