Despite the increasing popularity of the Ponseti method for the treatment of idiopathic congenital clubfeet, the relapse rate and sequela after the initial correction of manipulating and casting remain high. This study presents a scale to evaluate the relapse and identify the factors correlated with the relapse and latest follow-up mid-term results. A total of 101 children (newborn to 12 months), 142 idiopathic congenital clubfeet, were recruited for this study following treatment with the Ponseti method at the Hospital for Traumatology and Orthopaedics (Ho Chi Minh City, Vietnam) with a follow-up period of a minimum of 2 years. The clubfeet were then classified and evaluated during casting, for initial correction, and for relapse according to Diméglio’s score. Next, the latest follow-up results were evaluated according to Richards’ classification. The initial correction was successful in 95.8% (perfect: 74.0%, acceptable: 21.8%); 6.6% developed relapses and relapse-related factors were the initial correction and bracing program. The latest follow-up results are good in 74.7%, fair in 22.5%, and poor in 2.8%, and correlated with the age of presentation and the follow-up period in both univariate and multivariate analysis. On the basis of a precise evaluation of the relapse, this study indicates that the initial correction classified by the author on the basis of Diméglio’s score and bracing compliance affect relapse. In addition, early treatment after birth and continuous long-term follow-up to appropriately manage the sequelae are essential to obtain the latest follow-up results as expected.