Table 2.

Basic characteristics of studies included in risk factor analysis.

Reference	Study design	Number of		Age† (months)	Age group‡	Follow-up period (months)§	Failure type	Significant risk factors
		Patients*	Hips
Alassaf (45)	CSS	104	164	15.6 (5–24)	1	1.5 (N/A)	Failed reduction	- Higher age (P = 0.01) - IHDI grade 4 vs 2 (P = 0.001) - Decreased acetabular index (P = 0.02)
Arneill et al. (46)	RS	54	67	6 (3.93–12.07)	1	49 (19–89)	Overall failure	- Shorter length of time spent in harness - Graf 4
Bachy et al. (47)	PS	29	34	9.7 (2.1–33.9)	1	N/A (18–76)	Postoperative
		31	36		2
Barakat et al. (48)	PS	20	29	18.3 (9–36)	2	21 (18–24)	Overall failure
Bhaskar et al. (49)	RS	15	17	9.5 (6–16)	1	28 (24–36)	Redislocation
Danielsson (50)	PS	68	71	7 (2–22)	1	10.9 (5.5–17.5)	Intraoperative, redislocation, overall failure
Daoud et al. (51)	RS	13	20	26 (18–36)	1	48 (32–65)	Failed reduction, redislocation, overall failure
		25	35		2
Elerson et al. (52)	PS	96	115	13 ± 5.7	1	> 12	Overall failure
Elghobashy et al. (53)	RS	49	65	24 (9–30)	2	4.2 (3–11) years	Overall failure	- Increasing FAZ (femoro-acetabular zone) grade (P = 0.001)
Fleissner et al. (54)	RS	68	79	8 (1–36)	2	41.1 (12–120)	Redislocation	- Obstructive limbus (P = 0.001)
Forlin et al. (55)	RS	56	65	13 (3–31)	1	62 (24–151)	Redislocation
		60	71		2
Huang & Wang (56)	RS	16	17	17 ± 5.4	1	> 24	Failed reduction, redislocation, overall failure
Jones et al. (12)	RS	19	28	6 (3–10)	1	48 (12–102)	Overall failure
Kubo et al. (8)	RS	104	132	3 ± 2	1	2 (+/−1)	Postoperative, redislocation
Li et al. (57)	RS	385	440	16 ± 4.9	1	37.4 (24–117)	Failed reduction
Li et al. (58)	RS	276	308	15.3 (6–23.9)	1	41.9 (24–127)	Redislocation	- Tönnis grade 3–4 (P = 0.027)
Mitani et al. (59)	RS	N/A	38	N/A (12–31)	2	14 (10–21) years	Redislocation	- Interposed limbus
Morris et al. (60)	RS	N/A	104	13 ± 4.68	1	16.9 ± 3.8║ years	Intraoperative	- IHDI grade 4 (P < 0.001)
Murray et al. (61)	RS	30	35	6 (0.75–16.5)	1	> 20	Failed reduction
Pospischill et al. (62)	RS	64	78	4 (1.2–10.4)	1	6.3 (5.2–7.2) years	Intraoperative
Ramo et al. (63)	RS	N/A	235	N/A (6–36)	2	N/A (48-) in 131 hips	Overall failure	- Tönnis grade (3-)¶ 4 (Pp = 0.0028) - IHDI grade (3-)¶ 4 (Pp = 0.0000)
Sankar et al. (64)	PS	78	87	8 (1–20)	1	22 (12–36)	Failed reduction, redislocation, overall failure	- Irreducible hips on clinical and/or US exam (Ortolani neg dislocation) (initial success, P = 0.006) - High reduction grade on arthrogram (P < 0.001)
Schoenecker et al. (65)	RS	32	38	23 (18–35)	2	104 (36-)	Failed reduction, redislocation, overall failure
Senaran et al. (66)	RS	21	35	3 (1–7)	1	36 (12–78)	Failed reduction, redislocation, overall failure
Sucato et al. (67)	RS	299	342	11 (2–33)	2	10.4 (2–27.7) years	Overall failure	- Tönnis grade 4 (P = 0.001)
Talathi et al. (3)	PS	154	166	8.7 ± 4.1	1	N/A	Overall failure	- Graf 4 (P = 0.003) - Less femoral head coverage (P = 0.01) - Male gender (P = 0.04) - Irreducible hips (Ortolani neg) (P = 0.01) - IHDI grade 3–4 (P = 0.002)
Tennant et al. (4)	RS	120	133	9 (4–24)	1	N/A (5-) years	Overall failure	- Bilateral dislocations - Patients ≤ 12 months (P < 0.04) - Tönnis grade 4 (P < 0.003)
Tennant et al. (6)	RS	29	58	7 (3–13)	1	6.5 (3–12)║ years	Overall failure	- Tönnis grade 4 (in bilateral dislocations)
Terjesen & Horn (68)	RS	49	52	13 (3–33)	1	15.7 (13–21)║	Overall failure	- Age over 12 months (P = 0.026)
		N/A	46		2
Ucpunar et al. (69)	RS	53	65	8.1 ± 1.4	1	4.2 ± 1.5 years	Overall failure
Yilar et al. (70)	RS	218	302	7 (3–17)	1	26 (12-)	Redislocation	- Absence of ossific nucleus (P = 0.048)
Yu et al. (71)	RS	22	25	10 (3–18)	1	N/A	Postoperative
Yuan et al. (72)	RS	173	187	15.4 ± 4.4	1	N/A (12–36)	Failed reduction	- Age higher than 14.5 months (P = 0.023) - Poor delineation of the labrum or acetabular surface on arthrogram (P < 0.001), medial dye pool (mdp) distance ≥ 6 mm (P < 0.001)
Zhang et al. (73)	RS	107	156	13 (4–28)	1	6.7 ± 0.8║ years	Redislocation	- IHDI grade 4 (P = 0.004) - walking (P = 0.011)

*In different age groups, if any; ^†Average age in months (range or s.d.); ^‡Group 1: 0–24 months; group 2: 0–36 months; ^§Average follow-up period in months (range or mean ± S.D.); ^║Age at final follow-up; ^¶The respective grade 3 was also a significant risk factor in the publication, but the P value was not reported.

N/A: not available; CSS, cross-sectional study; PS, prospective study; RS, retrospective study.