Table 4.

Predictive factors for acetabular retroversion in stages II or IV according to Waldenström [24] in hips with Legg–Calvé–Perthes disease

	Parameter	Hazard ratio (95% confidence interval)	p value
Retroversion in Stage II	Age at stage II < 6 years	2.4 (1.3–4.2)	0.004
	Male gender	0.8 (0.2–3.1)	0.372
	Shenton line [9] not intact at stage II	0.5 (0.2–1.5)	0.220
	Herring lateral pillar classification [7] B or C at stage II*	2.5 (0.9–6.4)	0.066
Retroversion in Stage IV	Age at stage II < 6 years	4.2 (1.1–16.8)	0.042
	Age at stage IV < 12 years	1.4 (1.1–1.7)	0.007
	Male gender	2.3 (0.4–12.6)	0.342
	Non-dysplastic acetabulum (LCE angle < 20°) at stage IV	5.0 (1.7–10.0)	0.008
	Shenton line [9] not intact at stage IV	1 (0.7–3.3)	0.245
	Herring lateral pillar classification [7] group B or C at stage II*	3.6 (1.1–12.0)	0.036
	Stulberg classification [18] ≥ 3 at stage IV†	2.5 (0.6–5)	0.183

*hips with loss of height of the lateral pillar (Herring lateral pillar classification group B and C) were compared to those without of loss of height (Group A); ^†hips with a spherical head (Stulberg Class 1 or 2) were compared to hips with an aspherical or flat femoral head (Class 3 to 5)