Cast index in predicting outcome of pediatric forearm fractures

Abstract

Introduction: Prediction of Re-displacement of pediatric forearm fractures would be a boon for orthopaedic surgeons treating them conservatively. Cast index (CI), described by Chess et al. is calculated by measuring the internal antero-posterior (AP) diameter of the cast (excluding padding) at the level of the fracture and dividing it by the internal lateral diameter of the cast (excluding padding) which could be used as a tool to predict the re-displacement of fracture if it is maintao <0.8. Aims: The aim of the present study is to evaluate the role of cast index in predicting the re-displacement in pediatric forearm fracture. Materials and Methods: A hospital based prospective study was conducted in the Department of Orthopaedics, Silchar Medical College and Hospital, Assam. 83 paediatric patients ranging from 0 to 16 yrs with forearm fractures who met the inclusion criteria were recruited in our study. Patients with open fractures and with distal neurovascular deficit were excluded from our study. The fractures were treated with closed reduction with above elbow casts after manipulation. The cast index was measured immediately following casting on x-ray and patient was followed up weekly to check for redisplacement. Results: Out of 83 patients, proximal and distal fractures were 14 (18.07%) and 69 (81.92%) respectively. Mean cast index in proximal fractures and distal fractures which were displaced was 0.85 and 0.75 respectively. Out of 69 distal forearm fractures 7 were re-displaced and were re-manipulated, on the other hand only 1 out of 14 proximal forearm fracture was re-displaced and re-manipulated. Conclusion: Distal forearm fractures with cast index >0.8 were more likely toget re-displaced than with <0.8. It is difficult to achieve a cast index <0.8 in proximal forearm fractures, cast index < or > 0.8 does not predict the risk of re-displacement and re-manipulation in proximal forearm fractures. So, its use to predict the re-displacement should be discouraged in proximal fractures. It should be used to predict redisplacement in distal forearm fractures.