Natural History of Postoperative Adding-On in Adolescent Idiopathic Scoliosis: What Are the Risk Factors for Progressive Adding-On?

Table 1

Clinical and preoperative radiographical data.

	Progressive	Nonprogressive
Clinical data
Sex (female/male)	19/5	32/5	0.451
Age (year)	14.62 ± 2.15	15.33 ± 2.11	0.103
Follow-up (month)	43.81 ± 20.62	40.98 ± 15.91	0.274
Risser	1.88 ± 1.45	3.48 ± 1.14	<0.001
Triradiate cartilage (OTRC/CTRC)	15/9	11/26	0.011
LIV-SSV
<0	12	3	<0.001
0	9	12
>0	3	22
Preoperative radiographical data
PT curve (°)	28.99 ± 4.91	27.84 ± 6.03	0.219
Flexibility (%)	28.42 ± 13.21	26.92 ± 14.32	0.341
MT curve (°)	51.12 ± 10.54	49.52 ± 9.43	0.269
Flexibility (%)	53.24 ± 18.18	58.12 ± 17.12	0.146
Lumbar curve (°)	22.37 ± 7.21	23.51 ± 5.66	0.247
Flexibility (%)	82.93 ± 15.89	83.91 ± 18.12	0.415
Thoracic kyphosis (°)	11.52 ± 6.12	13.98 ± 8.21	0.107
Lumbar lordosis (°)	48.59 ± 6.35	47.58 ± 7.91	0.301

OTRC: open triradiate cartilage; CTRC: closed triradiate cartilage; LIV: lower instrumented vertebra; SSV: Substantially Stable Vertebra; LIV-SSV < 0: LIV proximal to SSV; LIV-SSV = 0: LIV at SSV; LIV-SSV > 0: LIV distal to SSV.