Risk factors and clinical significance of posterior slip of the proximal vertebral body after lower lumbar fusion

Table 2 Radiography parameters of the two groups, mean ± SD

	Nonretrograde group	Retrograde group	t value	P value
PI (°)
Preoperative	47.9 ± 9.2	57.8 ± 10.6	4.041	< 0.001
Postoperative	49.2 ± 9.6	58.1 ± 11.4	3.454	0.008
Final follow-up	49.6 ± 10.3	57.2 ± 11.9	2.768	< 0.001
PT (°)
Preoperative	20.5 ± 6.2	21.5 ± 6.4	0.621	0.536
Postoperative	15.6 ± 4.4	14.8 ± 5.6	0.665	0.508
Final follow-up	14.9 ± 3.9	15.3 ± 5.0	0.374	0.709
SS (°)
Preoperative	27.9 ± 8.3	35.1 ± 8.2	3.371	< 0.001
Postoperative	35.8 ± 7.9	42.7 ± 10.8	3.123	0.002
Final follow-up	37.1 ± 9.4	41.9 ± 7.7	2.049	0.043
LL (°)
Preoperative	34.1 ± 10.2	38.9 ± 14.8	1.649	0.103
Postoperative	48.7 ± 12.6	57.1 ± 10.6	2.664	0.009
Final follow-up	48.9 ± 9.7	56.3 ± 9.2	2.988	0.003
lLL (°)
Preoperative	24.9 ± 4.8	27.0 ± 6.8	1.546	0.126
Postoperative	38.1 ± 8.9	38.7 ± 9.9	0.255	0.799
Final follow-up	37.4 ± 9.6	38.9 ± 8.5	0.619	0.537
uLL (°)
Preoperative	8.1 ± 3.4	10.9 ± 4.7	2.934	0.004
Postoperative	12.5 ± 4.3	18.2 ± 6.4	4.605	< 0.001
Final follow-up	12.7 ± 5.6	17.6 ± 5.4	3.417	< 0.001

PI: Pelvic incidence; PT: Pelvic tilt; SS: Sacral slope; LL: Lumbar lordosis; lLL: Lower LL; uLL: Upper LL.