How long does it to achieve sagittal realignment of the displaced epiphysis in Salter-Harris type II distal radial fracture when treated by manual reduction?

This study aimed to investigate how long it takes for the dorsally displaced distal radial epiphysis to achieve realignment. We retrospectively reviewed 56 patients with dorsally displaced Salter-Harris type II distal radial epiphyseal fractures who were aged ≤15 years at the time of injury. All fractures were treated with closed reduction and immobilised using a sugar tong splint for 6 weeks. We evaluated the change in the displaced epiphysis position (%) until 12 weeks and the long-term clinical and radiological outcomes. We analysed significant differences in demographic factors and epiphyseal displacement according to the required period for epiphyseal realignment. The estimated area of the receiver operating characteristics (ROC) curve was calculated, and cut-off values were suggested to predict the required period for epiphyseal realignment. Sixteen (28.6%) and 42 (75%) patients achieved realignment of the epiphysis within 8 and 12 weeks, respectively. The cut-off values of 13.1 and 22.9% displacement at the 1-week follow-up were the best predictors of epiphyseal realignment within 8 and 12 weeks, respectively. Patients with a residual displacement of up to 51.3% in the sagittal plane at the 1-week follow-up achieved complete realignment of the epiphysis at the 6-month follow-up. From this study, we could predict the timing of epiphyseal realignment, and expect epiphyseal realignment even if re-displacement occurred up to 51.3% at the 1-week follow-up.