Table 1:

Patient demographics

	Group 1	Group 2	Group 3
No. of patients (female %)	328 (70%)	226 (64%)	101 (66%)
Mean age by year (SD)	75 (11)	74 (12)	73 (11)
Median % of available patients in different follow-up time points (range)	68% (22%–93%)	70% (32%–92%)	70% (26%–93%)
No. of levels	328	539	328
Upper thoracic (T1–T4)	1 (0.5%)	8 (1%)	7 (2%)
Mid thoracic (T5–T8)	64 (19.5%)	85 (16%)	55 (17%)
Lower thoracic (T9–T12)	100 (30.5%)	171 (32%)	112 (34%)
Upper lumbar (L1–L3)	125 (38%)	199 (37%)	115 (35%)
Lower lumbar (L4–L5)	35 (10.5%)	76 (14%)	38 (11.5%)
Sacrolplasty	3 (1%)	0	1 (0.5%)