Table 1 Baseline characteristics of all patients in collapse and no-collapse group

Follow-up, M (Q₁, Q₃)

29.55 (19.48, 40.83)

28.80 (19.43, 41.30)

29.90 (19.55, 39.95)

Z = −0.27

0.788

Gender, n (%)

χ² = 0.07

0.799

 Female

42 (19.81)

30 (20.27)

12 (18.75)

 Male

170 (80.19)

118 (79.73)

52 (81.25)

Age, M (Q₁, Q₃)

42.00 (33.00, 49.00)

40.50 (33.00, 50.00)

42.50 (35.75, 47.25)

Z = −0.01

0.992

BMI, M (Q₁, Q₃)

23.71 (21.58, 26.04)

23.66 (21.22, 26.05)

23.79 (22.32, 25.86)

Z = −1.12

0.262

Symptom duration,

M (Q₁, Q₃)

2.00 (1.00, 5.00)

2.00 (1.00, 4.25)

2.00 (1.00, 5.00)

Z = −0.36

0.716

Bisphosphonate, n (%)

χ² = 0.47

0.493

 No

115 (54.25)

78 (52.70)

37 (57.81)

 Yes

97 (45.75)

70 (47.30)

27 (42.19)

Laterality, n (%)

χ² = 0.24

0.888

 Unilateral MD and

contralateral THA

23 (10.85)

17 (11.49)

6 (9.38)

 Unilateral

57 (26.89)

39 (26.35)

18 (28.12)

 Bilateral

132 (62.26)

92 (62.16)

40 (62.50)

Etiology, n (%)

χ² = 3.26

0.196

 Idiopathic

121 (57.08)

84 (56.76)

37 (57.81)

 Corticosteroid

58 (27.36)

37 (25.00)

21 (32.81)

 Alcohol-related

33 (15.57)

27 (18.24)

6 (9.38)

Stage, n (%)

χ² = 5.87

0.053

 ARCO I

49 (23.11)

39 (26.35)

10 (15.62)

 ARCO II

108 (50.94)

77 (52.03)

31 (48.44)

 ARCO III A

55 (25.94)

32 (21.62)

23 (35.94)

Bone marrow Edema, n (%)

χ² = 9.50

0.002

 No

83 (39.15)

68 (45.95)

15 (23.44)

 Yes

129 (60.85)

80 (54.05)

49 (76.56)

Location, n (%)

χ² = 4.95

0.084

 Type B

15 (7.08)

13 (8.78)

2 (3.12)

 Type C1

67 (31.60)

51 (34.46)

16 (25.00)

 Type C2

130 (61.32)

84 (56.76)

46 (71.88)

Combined necrotic angle,

Mean ± SD

211.53 ± 44.58

204.23 ± 44.67

228.40 ± 39.82

t = −3.73

 < .001

Necrosis degree index,

Mean ± SD

114.91 ± 46.53

107.59 ± 45.18

131.84 ± 45.52

t = −3.58

 < .001