Table 1. Pre- and postoperative parameters values and JOA scores.

	Min	Max	Mean	SD	p Value
McGregor slope pre	−20	9	−4.0	6.7	0.07
McGregor slope post	−11	9	−2.0	5.8
T1 slope pre	17	47	30.9	7.8	0.40
T1 slope post	12	64	32.5	12.4
O–C2 angle pre	−13	25	4.7	10.7	0.0001
O–C2 angle post	−4	38	15.4	10.7
C2–C7 angle pre	4	50	21.8	13.8	0.002
C2–C7 angle post	−17	42	9.6	15.2
O–C7 angle pre	4	45	26.4	12.6	0.46
O–C7 angle post	4	60	25.0	14.1
JOA score pre	7.0	16.0	11.7	2.9	0.0001
JOA score post	8.5	17.0	13.6	2.7

Note: Wilcoxon signed rank test.

Abbreviations: JOA, Japanese Orthopaedic Association; Min, minimum; Max, maximum; O, occipito; pre, preoperative value; post, postoperative value; SD, standard deviation.