Iatrogenic Ulnar Nerve Injury After the Surgical Treatment of Displaced Supracondylar Fractures of the Humerus: Number Needed to Harm, A Systematic Review

Background: Supracondylar fractures of the humerus are common pediatric elbow injuries. Most displaced or angulated fractures are treated by closed reduction and percutaneous pinning, with either a crossed pin or lateral pin configuration. The purpose of this study was to conduct a systematic review to determine if there is an increased risk of iatrogenic nerve injury associated with the crossed pin configuration. Methods: Relevant articles were identified by searching electronic databases and hand searching-related journal and conference proceedings. Within each trial, the risk of iatrogenic ulnar nerve injury was calculated for each pinning technique. For studies comparing crossed versus lateral pinning, the resulting trial-based differences in risk estimates were pooled using a random effects meta-analysis. A number needed to harm was determined using the pooled risk difference. Results: Thirty-two trials consisting of 2639 patients were used in the pooled analysis. The pooled risk difference of iatrogenic ulnar nerve injury is 0.035 (95% confidence interval, 0.014-0.056), with a higher incidence of injury in the crossed pinning group. The weighed number needed to harm for the crossed pinning is 28 (95% confidence interval, 17-71). Conclusions: The results of this review suggest that there is an iatrogenic ulnar nerve injury for every 28 patients treated with the crossed pinning compared with the lateral pinning. Further research is necessary to ensure that the optimal pinning technique is chosen to treat these factors.