Do we need to do overcorrection in Blount's disease?

Purpose In order to prevent recurrent deformity, overcorrection in Blount's disease has been a common practice by most paediatric orthopaedic surgeons. However, some patients have persistent valgus alignment resulting in awkward deformity. The femoro-tibial angle (FTA) was measured in this series of cases to determine the necessity of such practice. Method During 1998-2010, patients with Blount's disease stage 2 by Langenskiold, aged from 30 to 40 months who had failed from bracing and underwent valgus osteotomy were included. Seventeen legs had postoperative FTA 7-13 degrees (group 1) and 48 legs had postoperative FTA more than 13 degrees (group 2). ROC curve was used to determine the appropriate FTA that was suitable to prevent recurrence. Results Four legs had recurrence (28.6 %) in group 1 and six legs (12.5 %) had recurrence in group 2. Chi-square test between two groups were not statistically significant in recurrence (p = 0.434). Age and BMI were not statistically significant between recurrent and non-recurrent groups. The ROC curve shows that overcorrection more than 15 degrees did not show benefit to prevent the recurrence in Blount's stage 2. Conclusion Our study showed that the overcorrection group had non-statistically significant recurrence compared to the non-overcorrection group, and overcorrection more than valgus 15 degrees has no benefit to prevent recurrence.