This is a meta-analysis of reported risk factors of a ‘bad split’ in a sagittal split mandibular osteotomy. They identified 30 observational articles and therefore acknowledged it is based on low quality studies. It is compounded by the definition of a bad split and its likely under-reporting. They concluded that there was no robust evidence to show that patient age, presence of third molars or surgical technique may influence the incidence of a bad split.