Two types of fracture, early and late, have been reported following limb lengthening in patients with achondroplasia (ACH) and hypochondroplasia (HCH). . We reviewed 25 patients with these conditions who underwent 72 segmental limb lengthening procedures involving the femur and/or tibia, between 2003 and 2011. Gender, age at surgery, lengthened segment, body mass index, the shape of the callus, the amount and percentage of lengthening and the healing index were evaluated to determine predictive factors for the occurrence of early (within three weeks after removal of the fixation pins) and late fracture (> three weeks after removal of the pins). The Mann‑Whitney U test and Pearson’s chi-squared test for univariate analysis and stepwise regression model for multivariate analysis were used to identify the predictive factor for each fracture. Only one patient (two tibiae) was excluded from the analysis due to excessively slow formation of the regenerate, which required supplementary measures. A total of 24 patients with 70 limbs were included in the study. There were 11 early fractures in eight patients. The shape of the callus (lateral or central callus) was the only statistical variable related to the occurrence of early fracture in univariate and multivariate analyses. Late fracture was observed in six limbs and the mean time between removal of the fixation pins and fracture was 18.3 weeks (3.3 to 38.4). Lengthening of the tibia, larger healing index, and lateral or central callus were related to the occurrence of a late fracture in univariate analysis. A multivariate analysis demonstrated that the shape of the callus was the strongest predictor for late fracture (odds ratio: 19.3, 95% confidence interval: 2.91 to 128). Lateral or central callus had a significantly larger risk of fracture than fusiform, cylindrical, or concave callus. Radiological monitoring of the shape of the callus during distraction is important to prevent early and late fracture of lengthened limbs in patients with ACH or HCH. In patients with thin callus formation, some measures to stimulate bone formation should be considered as early as possible. Cite this article: Bone Joint J 2014;96-B:1269–73

We present the results of 90 consecutive children with displaced fractures of the forearm treated by elastic stable intramedullary nailing with a mean follow-up of 6.6 months (2.0 to 17.6). Eight (9%) had open fractures and 77 (86%) had sustained a fracture of both bones. The operations were performed by orthopaedic trainees in 78 patients (86%). All fractures healed at a mean of 2.9 months (1.1 to 8.7). There was one case of delayed union of an ulnar fracture. An excellent or good functional outcome was achieved in 76 patients (84%). There was no statistical difference detected when the grade of operating surgeon, age of the patient and the diaphyseal level of the fracture were correlated with the outcome. A limited open reduction was required in 40 fractures (44%).

Complications included seven cases of problematic wounds, two transient palsies of the superficial radial nerve and one case each of malunion and a post-operative compartment syndrome. At final follow-up, all children were pain-free and without limitation of sport and play activities.

Our findings indicate that the functional outcome following paediatric fractures of the forearm treated by elastic stable intramedullary nailing is good, without the need for anatomical restoration of the radial bow.