Biodegradable metals for bone fracture repair in animal models: a systematic review

Biodegradable metals hold promises for bone fracture repair. Their clinical translation requires pre-clinical evaluations including animal studies, which demonstrate the safety and performance of such materials prior to clinical trials. This evidence-based study investigates and analyzes the performance of bone fractures repair as well as degradation properties of biodegradable metals in animal models. Data were carefully collected after identification of population, interventions, comparisons, outcomes and study design, as well as inclusion criteria combining biodegradable metals and animal study. Twelve publications on pure Mg, Mg alloys and Zn alloys were finally included and reviewed after extraction from a collected database of 2122 publications. Compared to controls of traditional non-degradable metals or resorbable polymers, biodegradable metals showed mixed or contradictory outcomes of fracture repair and degradation in animal models. Although quantitative meta-analysis cannot be conducted because of the data heterogeneity, this systematic review revealed that the quality of evidence for biodegradable metals to repair bone fractures in animal models is 'very low'. Recommendations to standardize the animal studies of biodegradable metals were proposed. Evidence-based biomaterials research could help to both identify reliable scientific evidence and ensure future clinical translation of biodegradable metals for bone fracture repair.