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

Table 3 Lumbar sagittal images of the patients in the two groups, mean ± SD

	Nonretrograde group	Retrograde group	t value	P value
|PI-LL| (°)
Preoperative	13.9 ± 5.2	15.3 ± 5.8	1.019	0.311
Postoperative	1.9 ± 4.3	1.4 ± 3.6	0.465	0.643
Final follow-up	0.9 ± 2.1	1.2 ± 3.0	0.671	0.504
PI-LL matching
Yes	63	16	0.142	0.706
No	9	3
LDI (%)
Preoperative	75.9 ± 14.9	71.1 ± 16.7	1.217	0.226
Postoperative	75.7 ± 10.4	68.1 ± 11.5	2.772	0.006
Final follow-up	74.3 ± 9.4	67.2 ± 11.9	2.764	0.006
Distribution of LL
LDI < 50%	6	7	49.937	< 0.001
50% ≤ LDI < 80%	64	12
80 ≤ LDI	2	0

PI: Pelvic incidence; LL: Lumbar lordosis; lLL: Lower LL; LDI: Lordosis distribution index.