Table 1.

Demographic characteristics

	S1 screw non-loosening group	S1 screw loosening group	P value
Age	61.5 ± 7.3	65.3 ± 4.7	0.011
Sex (Male/Female)	9/37	5/27	0.656
BMI	26.3 ± 4.3	25.8 ± 4.3	0.67
Number of fused levels	6.2 ± 1.8	6.2 ± 2.0	0.968
Osteoporosis	20.6%(7/34)	75.0%(18/24)	<0.001
L1-L4 average T score	−0.6 ± 2.2	−1.7 ± 1.6	0.034
T score of total hip joint	−1.0 ± 1	−1.6 ± 0.7	0.033
History of smoking	6.5%(3/46)	3.1%(1/32)	0.504
Menopause	78.3%(36/46)	78.1%(25/32)	0.989
Hypertension	32.6%(15/46)	62.5%(20/32)	0.009
Diabetes mellitus	23.9%(11/46)	21.9%(7/32)	0.834
Coronary artery disease	2.2%(1/46)	12.5%(4/32)	0.067
Fusion rate	95.7%(44/46)	90.6%(29/32)	0.373
Interbody fusion	78.3%(36/46)	75%(24/32)	0.789
L5/S1 interbody fusion	19.6%(9/46)	31.3%(10/32)	0.237
Deep infection	2.2%(1/46)	6.3%(2/32)	0.357
Cerebrospinal fluid leakage	2.2%(1/46)	0%(0/32)	0.401