Effects of ionizing radiation on bone microstructure and biomechanical properties: a systematic review in clinical and aerospace contexts

: Introduction. This review examines the impact of ionizing radiation on bone microstructure and mechanical properties in murine models, with particular attention to how different radiation types, total absorbed doses, and dose rates influence skeletal tissue. The topic is highly relevant in both radiotherapy and aerospace research, two different scenarios but that share important skeletal consequences, such as disturbances in bone remodeling, deterioration of trabecular and cortical microarchitecture, and reductions in mechanical strength.Methods. This review was conducted following PRISMA guidelines, with a structured search across Scopus, PubMed, and Google Scholar using predefined keywords and Boolean operators. Experimental murine studies investigating the effects of ionizing radiation in radiotherapy- or spaceflight-simulating settings were considered eligible if they reported at least one bone morphological and one mechanical outcome. After screening and eligibility assessment, 11 studies were included and evaluated for methodological quality based on the robustness of the reported morphological and mechanical analyses.Results. The included studies indicate that radiation exposure in murine bone is associated with dose-, time-, and radiation quality-dependent deterioration, with early, transient effects after single doses and more persistent damage following repeated exposures. Trabecular bone emerged as the most vulnerable compartment, showing reduced trabecular number and increased separation across several studies. Mechanical outcomes appeared to be site-specific: cortical-rich bones often retain strength despite trabecular loss, whereas trabecular-rich sites appeared more susceptible, suggesting microstructural deterioration may contribute to functional impairment even when whole-bone strength is relatively preserved.Conclusions. These findings highlight that trabecular bone is the primary target of radiation-induced damage, with site-specific effects and persistent mechanical deficits, emphasizing the importance of multiscale assessment to understand and mitigate skeletal fragility in clinical and spaceflight contexts. However, a limited number of eligible studies and heterogeneity of experimental designs could reduce the strength of direct comparisons and the generalizability of these conclusions.