Incidence and risk factors for redisplacement after closed reduction and instant rigid cast immobilization for paediatric distal radius fractures: a case control study

ABSTRACT: BACKGROUND: The aim of this study is to record the incidence of redisplacement after closed reduction and instant rigid cast immobilization and to identify possible risk factors that may be associated with the redisplacement. METHODS: We retrospectively reviewed paediatric patients who underwent closed reduction and instant rigid cast immobilization for simple distal radius fractures from 2014 to 2018. Patients were followed up at 1 week, 2 weeks, 3 weeks, and 6 weeks after casting. Redisplacement was diagnosed on the basis of image findings. Risk factors for redisplacement were evaluated in three aspects, which included patient-related, fracture-related, and cast-related factors. RESULTS: A total of 123 children were included in this study. During follow-up, 31 patients (25.2%) showed redisplacement after closed reduction and cast immobilization. Twenty-two redisplacements happened within 1 week after treatment, 8 redisplacements happened between 1 and 2 weeks, and only one redisplacement happened after 2 weeks. In the multivariate analysis, associated ulna fracture (OR, 4.278; 95% CI, 1.773–10.320), initial translation ≥ 50% (OR, 9.148; 95% CI, 3.587–23.332), and 3-point index ≥ 0.40 (OR, 1.280; 95% CI, 1.159–1.401) were three independent factors that correlated with the incidence of redisplacement during follow-up. CONCLUSIONS: About a quarter of paediatric patients would develop redisplacement after reduction and immobilization with instant rigid cast. Patients with associated ulna fracture, severe initial translation, and high 3-point index have a higher risk to develop redisplacement.