Table 1.

Summary of the Preoperative Demographics of Patients with or without PS Loosening 1 Year after Surgery.

	Loosening		P
	(–) (n=11)	(+) (n=21)
Age, *y	64.5±16.5	72±8.2	0.098
Sex (female/male)	5/6	9/12	0.9
BMD* (young adult mean %)	75.8±19.5	79±14	0.69
Stabilized length*	4.73±1.0	4.67±1.28	0.89
Smoker (%)	2 (25%)	3 (14.3%)	0.9
No. of loosening PS (%)	0 (0%)	44 (15.6%)
Primary diagnosis
Trauma	9	16
Infection	0	2
Metastasis	2	3

PS=pedicle screw; BMD=bone mineral density; *mean±standard deviation (SD)