Sequential sagittal alignment changes in the cervical spine after occipitocervical fusion

Table 1 Radiological parameters of patients in the occipitocervical fusion and control groups

	OCF (n = 84)			Control (n = 42)
	Pre-op	Post-op	Final follow-up
O-C2a (°)	4.7 ± 15.3	4.6 ± 12.6	4.7 ± 13.3	12.0 ± 8.2a,b,c
O-EAa (°)	101.1 ± 8.5	99.4 ± 7.7	99.0 ± 9.1	92.2 ± 5.4a,b,c
C2Ta (°)	96.5 ± 17.3	94.8 ± 13.5	94.2 ± 13.2	80.0 ± 8.6a,b,c
C2-7a (°)	24.8 ± 18.1	21.7 ± 16.1	21.6 ± 15.8	16.2 ± 9.6a,b,c
T1 slope (°)	23.2 ± 9.5	23.4 ± 8.2	21.5 ± 8.2	21.9 ± 7.2
C2-7 SVA (cm)	1.4 ± 1.1c	1.5 ± 1.1c	1.0 ± 1.0a,b	1.5 ± 0.8c
PIA (°)	91.6 ± 10.3	89.3 ± 10.1	88.8 ± 12.5	97.3 ± 7.5a,b,c

^aP < 0.05 compared with pre-op.

^bP < 0.05 compared with post-op.

^cP < 0.05 compared with final follow-up.

OCF: Occipitocervical fusion; Pre-op: Preoperative; Post-op: 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.