Table 5.

Factors of distal adding-on phenomenon

Radiographic parameters	Balanced group	Unbalanced group	p Value
	(fusion mass shift ≤ 20 mm)	(fusion mass shift > 20 mm)
Immediate postoperative
Lower instrumented vertebrae/lower instrumented vertebrae + 1 disc angle	−0.1 ± 3	−2 ± 6	0.26
Lower instrumented vertebrae + 1 shift	−12 ±12	−13 ±16	0.75
Postoperative 2-year followup
Lower instrumented vertebrae/lower instrumented vertebrae + 1 disc angle	1 ± 4	0.5 ± 6	1.0
Lower instrumented vertebrae + 1 shift	−8 ± 12	−5 ± 16	0.66

Values = mean ± SD.