Objectives. Fifteen potentially low value practices in adult orthopaedic trauma care were previously identified in a scoping review. The aim of this study was to synthesize the evidence on these practices. Methods. We searched four databases for systematic reviews, randomized controlled trials (RCTs), cohort studies and case series that assessed the effectiveness of selected practices. Methodological quality was evaluated using the Measurement Tool to Assess Systematic Reviews version 2 (AMSTAR-2) for systematic reviews and the Critical Appraisal Checklist for Case Series. We evaluated risk of bias with the Cochrane revised tool for RCTs and the risk of bias in non-randomized studies of interventions tool for observational studies. We summarized findings with measures of frequency and association for primary outcomes. Results. Of the 30,670 records screened, 70 studies were retained. We identified high-level evidence of lack of effectiveness or harm for routine initial imaging of ankle injury, orthosis for A0-A3 thoracolumbar burst fracture in patients < 60 years of age, cast or splint immobilization for suspected scaphoid fracture negative on MRI or confirmed fifth metacarpal neck fracture, and routine follow-up imaging for distal radius and ankles fractures. However, evidence was mostly based on studies of low methodological quality or high risk of bias. Conclusion. In this review, we identified clinical practices in orthopedic injury care which are not supported by current evidence and whose use may be questioned. In future research we should measure their frequency, assess practice variations and evaluate root causes to identify practices that could be targeted for de-implementation.