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

Background: The purpose of this study was to prospectively evaluate our recently described fetal sonographic classification system for prenatal diagnosis of clubfoot. Methods: 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 χ2 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. Results: 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). Conclusion: 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.