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

Table 1 Patient demographic data, mean ± SD

	Nonretrograde group	Retrograde group	t value	P value
Age (year)	51.7 ± 10.6	52.4 ± 11.3	0.258	0.797
Sex (male/female)	18/54	4/15	0.128	0.721
Operation time (minute)	257.3 ± 46.9	264.7 ± 43.8	0.619	0.540
Blood loss (mL)	219.6 ± 49.3	207.7± 56.5	0.907	0.367
Follow-up time (month)	27.4 ± 6.3	26.9 ± 7.0
Fixed segment	2.4 ±0.69	2.5 ± 0.74	0.554	0.581
Fusion segment
1	59	14	0.646	0.421
2	13	5
Fixation of S1
Yes	12	5	0.921	0.337
No	60	14