Supplementary Material for: Prospective Evaluation of a Prenatal Sonographic Clubfoot Classification System

<strong><em>Background:</em></strong> The purpose of this study was to prospectively evaluate our recently described fetal sonographic classification system for prenatal diagnosis of clubfoot. <b><i>Methods:</i></b> Over 18 months, we prospectively enrolled consecutive pregnant patients evaluated for a prenatally diagnosed clubfoot. Prenatal sonographic scores assigned by a radiologist were compared to final clinical diagnosis and severity given by a pediatric orthopedic surgeon. Pearson's χ<sup>2</sup> test and logistic regression were used in statistical analyses on the subject level. Generalized estimating equations were used in analyses on the foot level to account for intrasubject correlation. <b><i>Results:</i></b> There were 50 subjects, with 26 unilateral and 24 bilateral clubfeet, according to the prenatal ultrasound (US). A total of 51 (69%) of 74 feet and 36 (72%) of 50 subjects had a postnatal diagnosis of clubfoot. The accuracy of diagnosis in cases of a severe, moderate, and mild US score was 94, 70, and 25%, respectively (p = 0.003 comparing moderate-severe vs. mild). US severity correlated with the Dimeglio classification scoring system (Spearman's correlation 0.30). <b><i>Conclusion:</i></b> The fetal sonographic scoring system is predictive of clinical severity after birth, and improves the ability to counsel families with a prenatal diagnosis of clubfoot.