Table 2 Univariate and multivariate Cox regression analysis of association between different factors and failure of core decompression

 Stage I

1 (reference)

<.001

1 (reference)

1 (reference)

.641

1 (reference)

 Stage II A

.781

.749

.171–3.565

1.741

.491

.359–8.432

 Stage II B

4.749

.035

1.115–20.221

1.162

.849

.249–5.413

Preoperative Harris score

1.051

.190

.976–1.132

–

–

–

 A

1 (reference)

<.001

1 (reference)

1 (reference)

.582

1 (reference)

 B

.418

.538

.026–6.698

.306

.411

.018–5.163

 C1

5.242

.111

.685–40.097

1.231

.857

.127–11.896

 C2

18.644

.004

2.494–139.395

1.458

.752

.140–15.145

  < 15%

1 (reference)

<.001

1 (reference)

1 (reference)

.001

1 (reference)

 15–30%

3.708

.109

.747–18.408

3.170

.196

.551–18.255

  > 30%

32.521

<.001

7.695–137.444

22.293

.001

2.506–141.752

Bone marrow edema

3.814

<.001

1.935–7.518

2.188

.046

1.015–4.719

 Grade 0–1

1 (reference)

<.001

1 (reference)

1 (reference)

.001

1 (reference)

 Grade 2

6.004

<.001

2.768–13.022

3.579

.002

1.583–8.092

 Grade 3–4

6.771

<.001

2.833–16.186

5.036

.001

1.863–13.615