Redisplacement after Closed Reduction in Pediatric Both-Bone Forearm Fractures: The Role of Initial Fracture Angulation and Cast Index

Background: Both-bone forearm fractures are common in children and often treated with closed reduction and casting, though redisplacement remains a concern. This study investigates whether initial fracture angulation and cast index can reliably predict redisplacement and post-treatment angulation outcomes. Materials and Methods: A total of 53 skeletally immature patients with closed both-bone forearm fractures were included. Baseline radiographs assessed fracture location, angulation, displacement, and apex direction. Correlation and regression analyses evaluated the relationship between initial angulation, cast index, and angulation at follow-up. A binary logistic regression model assessed the predictive value of cast index and initial angulation for early redisplacement. Additionally, a receiver operating characteristic (ROC) curve was generated to determine the optimal angulation threshold for predicting redisplacement. Results: At 6 weeks, the mean residual angulation was 6.63° (standard deviation = 4.92). Redisplacement occurred in 5 patients (10%) within the first 2 weeks. No significant differences were observed in outcomes based on sex, fracture location, or apex type. Cast index correlated strongly with 6-week angulation ( r = 0.619), while initial angulation strongly correlated with 2-week angulation ( r = 0.623) and moderately with 6-week angulation ( r = 0.478). Initial angulation significantly predicted early redisplacement ( P < 0.05). ROC analysis showed an AUC of 0.920 ( P = 0.02), with an angulation threshold of 23° yielding 100% sensitivity and 80% specificity. Conclusions: Initial fracture angulation is a stronger predictor of early redisplacement than cast index. Angulations exceeding 23° significantly increase the risk of redisplacement. Further studies with larger cohorts and longer follow-up are warranted.