We present a method of manipulative reduction, immobilisation and fixation using a U-shaped plaster with the elbow in extension for extension-type supracondylar fractures of the humerus in children. When the elbow is in full extension, both the extensor and the flexor muscles are neutralised during manipulative reduction and the carrying angle can be easily assessed thus preventing cubitus varus, the most common complication. In order to evaluate the efficiency of this method, we compared the clinical results of the new method with those of conventional treatment. In a group of 95 children who sustained an extension-type supracondylar fracture of the humerus, 49 were treated by the new method and 46 by the conventional method, reduction and immobilisation in a plaster slab with the elbow in flexion. Reduction and immobilisation were easily achieved and reliably maintained by one manipulation for all the children treated by the new method. In 12 children treated by the conventional method, the initial reduction failed and in seven secondary displacement of the distal fragment occurred during the period of immobilisation in plaster. All required a second or third manipulation. Of the 46 children, 28 (60.9%) had developed cubitus varus at a mean follow-up of 4.6 years when treated by the conventional method. None of the children treated by the new method developed cubitus varus. The mean score, according to the Hospital for Special Surgery (HSS) elbow scoring system, was 91 points using the new method and 78 with the conventional method. The results were statistically significant with regard to the incidence of cubitus varus and the elbow score (p <
0.01) suggesting that the new method is reliable and gives a satisfactory outcome.