Fractures of the forearm (radius or ulna or both) in children have traditionally been immobilised in plaster of Paris (POP) but synthetic cast materials are becoming more popular. There have been no randomised studies comparing the efficacy of these two materials. The aim of this study was to investigate which cast material is superior for the management of these fractures. We undertook a single-centre prospective randomised trial involving 199 patients with acute fractures of the forearm requiring general anaesthesia for reduction. Patients were randomised by sealed envelope into either a POP or synthetic group and then underwent routine closed reduction and immobilisation in a cast. The patients were reviewed at one and six weeks. A satisfaction questionnaire was completed following the removal of the cast. All clinical complications were recorded and the cast indices were calculated. There was an increase in complications in the POP group. These complications included soft areas of POP requiring revision and loss of reduction with some requiring re-manipulation. There was an increased mean padding index in the fractures that lost reduction. Synthetic casts were preferred by the patients.

This study indicates that the clinical outcomes and patient satisfaction are superior using synthetic casts with no reduction in safety.

Cite this article: Bone Joint J 2013;95-B:1285–9.

Redisplacement is the most common complication of immobilisation in a cast for the treatment of diaphyseal fractures of the forearm in children. We have previously shown that the three-point index (TPI) can accurately predict redisplacement of fractures of the distal radius. In this prospective study we applied this index to assessment of diaphyseal fractures of the forearm in children and compared it with other cast-related indices that might predict redisplacement. A total of 76 children were included. Their ages, initial displacement, quality of reduction, site and level of the fractures and quality of the casting according to the TPI, Canterbury index and padding index were analysed. Logistic regression analysis was used to investigate risk factors for redisplacement. A total of 18 fractures (24%) redisplaced in the cast. A TPI value of > 0.8 was the only significant risk factor for redisplacement (odds ratio 238.5 (95% confidence interval 7.063 to 8054.86); p < 0.001). The TPI was far superior to other radiological indices, with a sensitivity of 84% and a specificity of 97% in successfully predicting redisplacement. We recommend it for routine use in the management of these fractures in children. Cite this article: Bone Joint J 2013;95-B:563–7

We present an objective method for predicting the redisplacement of paediatric forearm and wrist fractures. Novel radiographic measurements were defined and their value assessed for clinical decision making. In Phase I of the study we defined the cast index and padding index and correlated these measurements with the incidence of fracture redisplacement. Phase II assessed these indices for their value in clinical decision making. Cast Index (a/b) is the ratio of cast width in lateral view (a) and the width of the cast in AP view (b). Padding Index (x/y) isthe ratio of padding thickness in the plane of maximum deformity correction (x) and the greatest interosseous distance (y) in AP view. The sum of cast index and padding index was defined as the Canterbury Index. In Phase I, 142 children's radiographs were analysed and a statistically significant difference was identified between redisplacement and initial complete off-ending of the bones, cast index > 0.8 and padding index of > 0.3. There was no significant association with age, fracture location, seniority of surgeon or angulation. In Phase II, radiographs of 5 randomly selected cases were presented to 40 surgeons (20 consultants & 20 registrars). Following an eyeball assessment they were asked to measure the cast index and padding index (after instruction). With eyeballing the consultants predicted 33% and registrars 25% of the cases that redisplaced. After learning to measure the indices the accuracy increased to 72% for consultants and 81% for registrars (p<0.001). We conclude that the cast index, padding index and Canterbury Index are validated tools to assess plaster cast quality and can be used to predict redisplacement of paediatric forearm fractures after manipulation. They can easily be taught to orthopaedic surgeons and are more accurate than eyeballing radiographs in the clinical setting. Redisplacement can be predicted if cast index > 0.8, padding index > 0.3 and Canterbury Index > 1.1

We assessed two simple radiological methods of predicting redisplacement of forearm fractures in children: a) Cast Index (ratio of sagittal to coronal cast width at the fracture site), and b) Padding Index (ratio of padding thickness at the fracture site in the plane of the deformity to the maximum interosseous width). Case records and radiographs of 100 children who underwent a manipulation under general anaesthesia for a displaced fracture of forearm or wrist were studied. Redisplacement was defined as more than 15 degrees of angulation and/or more than 50 percent of translational displacement on check radiographs at 1–2 weeks. Angulation (in degrees) and translation displacement (in percentage) were measured on the initial and check radiographs. Cast index and Padding index were measured on the check radiographs. Good intra and inter observer reproducibility was observed for both these measurements. The cast index was validated in an experimental study. Redisplacement was seen in 29 cases. Of these 21 cases underwent a secondary procedure for redisplacement. Initial displacement, cast index and padding index were the three factors which were significantly higher in the redisplacement group (p< 0.05). The means and 95% Confidence intervals for cast index and padding index were 0.88 (0.84, 0.90) and 0.48 (0.39, 0.62) in the redisplacement group whereas were 0.71 (0.69, 0.72) and 0.11 (0.09, 0.12) in the group with no redis-placement respectively. No statistically significant difference was seen for age, fracture location, initial angular deformity and seniority of the surgeon. Conclusion: cast index and padding index are simple and reliable radiographic measurements to predict the redisplacement of forearm fractures in children. A plaster with a cast index of> 0.9 and padding index of > 0.3 is prone to redisplacement

The aims of this study were i) to see if there is an association between poorly applied plasters and redisplacement of paediatric forearm fractures, and ii) to define reliable radiographic measurements to predict redisplacement of these fractures. The two radiographic measurements which were assessed were Cast Index and Padding Index which are a guide to plaster moulding and padding respectively. The sum of these was termed as the Canterbury Index. Case records and radiographs of 142 children who underwent a manipulation for a displaced fracture of forearm were studied. Angulation, translation displacement, Cast index and Padding index were measured on radiographs. Redisplacement was seen in 44 cases (32.3%). The means and 95 % Confidence intervals for cast index and padding index were 0.87 (0.84, 0.90) and 0.42 (0.39, 0.62) in the redisplacement group whereas were 0.71 (0.69, 0.72) and 0.11 (0.09, 0.12) in the group with no redisplacement respectively. Initial displacement, Cast index, Padding index and Canterbury Index were significantly greater in the redisplacement group (p< 0.005). No statistically significant difference was seen for age, fracture location, initial angular deformity and seniority of the surgeon. We suggest that Cast Index > 0.8, Padding Index > 0.3 and Canterbury Index > 1.1 are significant risk factors for redisplacement of conservatively treated paediatric forearm fractures