Table 2. Analysis of factors related to avascular necrosis of the femoral head in 28 children.

Factor	Avascular necrosis of the femoral head		Sum (N = 28)	P
	N (%) or Median (p25, p75)
	No (N = 22)	Yes (N = 6)
Age in years	7.5 (5.7, 12.1)	11.05 (9.7, 12.5)	9.4 (6.2, 12.1)	0.218
Sex
Female	4 (18.18)	3 (50)	7 (25)	0.117
Male	18 (81.82)	3 (50)	21 (75)
Displacement degree (Garden)
Insignificant displacement (Garden types Ⅰ and Ⅱ)	16 (72.73)	0 (0)	16 (57.14)	0.001
Medium displacement (Garden type Ⅲ)	4 (18.18)	2 (33.33)	6 (21.43)
Significant displacement (Garden type Ⅳ)	2 (9.09)	4 (66.67)	6 (21.43)
Fracture classification (Delbet)
Ⅰ	2 (9.09)	2 (33.33)	4 (14.29)	0.438
Ⅱ	6 (27.28)	1 (16.67)	7 (25)
Ⅲ	12 (54.54)	3 (50)	15 (53.57)
Ⅳ	2 (9.09)	0 (0)	2 (7.14)
Mechanism of injury
Fall injury	17 (77.27)	6 (100)	23 (82.14)	0.436
Traffic accident trauma	3 (13.64)	0 (0)	3 (10.71)
Crush by heavy objects	2 (9.09)	0 (0)	2 (7.15)
Surgery timing
Early surgery	6 (27.27)	0 (0)	6 (21.43)	0.255
Delayed surgery	16 (72.73)	6 (100)	22 (78.57)
Reduction quality
Satisfactory	21 (95.46)	2 (33.33)	23 (82.14)	0.001
Unsatisfactory	1 (4.54)	4 (66.67)	5 (17.86)

P<0.05 was considered statistically significant.