Re-displacement of paediatric forearm fractures: role of plaster moulding and padding.

Re-displacement of paediatric forearm and wrist fractures following manipulation and cast application is a common complication. Poor plaster application technique is an important risk factor for re-displacement. However, there are no reliable and validated objective radiological measurements to differentiate a well-applied plaster cast from a poorly padded and moulded cast. This study was conducted in the background of this fact. We have attempted to define simple, reliable and objective radiological measurements to determine the quality of moulding and padding of the plaster thereby predicting re-displacement of fractures in this group. The two radiographic measurements used in this study are Cast index and Padding index, which are a guide to plaster moulding and padding, respectively. Case records and radiographs of 142 children who underwent a manipulation for a displaced fracture of forearm or wrist were studied. Angulation, translation displacement, Cast index and Padding index were measured on radiographs. The sum of the Cast index and Padding index was termed as the Canterbury index. Re-displacement was seen in 44 cases (32.3%). Cast index, Padding index and Canterbury index were significantly greater in the re-displacement group as compared to the cases where no re-displacement was seen (p<0.005). Improvement in the plaster application skills as monitored by these indices reduced the re-displacement rate by 50%. We suggest that a high Cast index of more than 0.8, Padding index of more than 0.3 and the combined Canterbury index of 1.1 are important risk factors for re-displacement of these fractures.