The British Orthopaedic Surgery Surveillance study: Perthes' disease: the epidemiology and two-year outcomes from a prospective cohort in Great Britain.

Ordinal regression suggests that age and sex were the only baseline factors associated with two-year Stulberg grade, with the degree of lateral pillar collapse near to statistical significance: children aged six years or more at baseline, and/or female, and/or > 50% lateral column collapse were more likely to have a worse outcome at two years.

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