Table 2.

Vertical posterior acetabular arc angle (PAAA) for the femoral head of normal contralateral acetabula and unstable posterior hip fracture–dislocation, including high and low posterior acetabular wall fractures in term of vertical PAAA and complications

Patient no.		Normal contralateral acetabulum	Unstable posterior fracture dislocation hip	Vertical PAAA above/below centroacetabulo–greater sciatic notch line (°)		Complications
		Intact vertical PAAA (°)	Vertical PAAA of posterior wall fracture (°)	High	Low
1		106	74	24	–
2		139	116	43	–	Avascular necrosis of femoral head
3		123	112	56	–	Avascular necrosis of femoral head, postoperative sciatic nerve injury
4		126	83	22	–	Postoperative sciatic nerve injury
5		130	90	33	–	Avascular necrosis of femoral head
6		131	103	28	–
7		131	63	–	0
8		137	126	19	–	Avascular necrosis of femoral head, postoperative sciatic nerve injury
9		117	125	46	–
10		128	123	5	–
11		143	134	47	–	Hip osteoarthritis
12		122	98	12	–
13		129	94	–	14
14		146	74	–	6
15		134	114	29	–
16		117	99	41	–
17		120	119	50	–
18		118	112	63	–
19		117	113	–	3
20		125	94	42	–
21		110	69	–	12
Mean (standard deviation)		126.14 (10.36)	101.67 (20.44)	35.00 (16.18)	7.00 (5.92)
95 % confidence interval		121.43, 130.86	92.36, 110.97	26.38, 43.62	0, 14.35
	Intraobserver 1	0.910	0.872	0.863*
Intraclass correlation coefficient	Intraobserver 2	0.895	0.856	0.868*
	Interobserver	0.857	0.823	0.821*

*ICC of vertical PAAA above and below centroacetabulo–greater sciatic notch line