Sequential sagittal alignment changes in the cervical spine after occipitocervical fusion

Table 3 Radiological parameters of patients with dysphagia and without dysphagia

		Dysphagia (n = 20)	Without dysphagia (n = 64)	P value
O-C2a (°)	Pre-op	9.7 ± 10.7	3.2 ± 16.2	0.046
	Post-op	0.9 ± 9.3a	5.8 ± 13.3	0.128
	Final follow-up	1.3 ± 9.6a	5.8 ± 14.1	0.182
O-EAa (°)	Pre-op	104.2 ± 7.8	100.2 ± 8.6	0.070
	Post-op	95.1 ± 8.3a	100.8 ± 6.6	0.003
	Final follow-up	96.9 ± 6.5a	99.7 ± 9.7	0.240
C2Ta (°)	Pre-op	94.5 ± 13.1	97.1 ± 18.5	0.478
	Post-op	94.3 ± 14.1	94.9 ± 13.4	0.851
	Final follow-up	95.6 ± 10.6	93.8 ± 14.0	0.598
C2-7a (°)	Pre-op	19.5 ± 14.3	26.4 ± 19.0	0.136
	Post-op	26.9 ± 13.5a	20.0 ± 16.6	0.100
	Final follow-up	27.9 ± 12.6a	19.6 ± 16.2	0.041
T1 slope (°)	Pre-op	21.5 ± 5.7	21.2 ± 11.1	0.340
	Post-op	21.5 ± 6.8	24.4 ± 8.9	0.226
	Final follow-up	22.7 ± 6.5	20.9 ± 9.1	0.436
C2-7 SVA (cm)	Pre-op	0.9 ± 0.9	1.6 ± 1.1	0.028
	Post-op	1.1 ± 1.3	1.6 ± 1.1	0.088
	Final follow-up	0.4 ± 1.1b	1.2 ± 0.9	0.002
PIA (°)	Pre-op	95.0 ± 6.7	90.6 ± 11.0	0.035
	Post-op	82.0 ± 5.7a	91.6 ± 10.2	0.000
	Final follow-up	86.3 ± 6.8a,b	89.5 ± 13.7	0.321

^aP < 0.05 compared with pre-op.

^bP < 0.05 compared with post-op.

Pre: Preoperative; Post: Postoperative; O-C2a: O-C2 angle; O-EAa: Occipital and external acoustic meatus to axis angle; C2Ta: C2 tilting angle; C2-7a: C2-7 angle; SVA: Sagittal vertical axis; PIA: Pharyngeal inlet angle.