Efficacy of Rhizoma Drynariae (Drynaria roosii Nakaike) extracts in treating osteoporosis in rat models: A systematic review and meta-analysis.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE: Rhizoma Drynariae (Drynaria roosii Nakaike, Polypodiaceae) is a traditional Chinese medicinal herb used for the treatment of bone fractures and osteoporosis. The rhizome, rich in flavonoids, has shown osteoprotective effects in preclinical studies, yet a comprehensive synthesis of its efficacy in experimental osteoporosis models remains lacking. AIM OF THE STUDY: This study aimed to systematically evaluate the efficacy of Rhizoma Drynariae extracts on bone mineral density (BMD), trabecular microarchitecture, biomechanical properties, and bone metabolism in rat models of osteoporosis. MATERIALS AND METHODS: A systematic review and meta-analysis of randomized controlled animal studies were performed. Seven electronic databases were searched to identify eligible studies. Two reviewers independently extracted data and assessed study quality. The primary outcome was BMD, and secondary outcomes included trabecular parameters, biomechanical indices (maximum stress, ultimate load, Young's modulus, structure model index), and bone turnover markers (PINP, TRACP, ALP, osteocalcin, estradiol (E2), serum calcium, serum phosphorus). Meta-analyses were conducted using random- or fixed-effect models depending on heterogeneity, with subgroup and sensitivity analyses performed to assess robustness. RESULTS: Thirty-one studies involving 31 experiments were included. Rhizoma Drynariae extracts significantly increased BMD (SMD&#xa0;=&#xa0;3.33, 95% CI&#xa0;=&#xa0;2.69-3.97), trabecular number (SMD&#xa0;=&#xa0;4.66, 95% CI&#xa0;=&#xa0;3.45-5.87), trabecular thickness (MD&#xa0;=&#xa0;31.03&#xa0;&#x3bc;m, 95% CI&#xa0;=&#xa0;22.85-39.22), and bone volume fraction (SMD&#xa0;=&#xa0;3.47, 95% CI&#xa0;=&#xa0;2.58-4.35), while reducing trabecular separation (SMD&#xa0;=&#xa0;-3.40, 95% CI&#xa0;=&#xa0;-4.35 to -2.45). Biomechanical parameters including maximum stress, ultimate load, Young's modulus, and structure model index were markedly improved. Bone metabolism analysis revealed elevated E2 (SMD&#xa0;=&#xa0;1.13, 95% CI&#xa0;=&#xa0;0.59-1.67) and PINP levels (SMD&#xa0;=&#xa0;4.29, 95% CI&#xa0;=&#xa0;0.57-8.01), and decreased TRACP (SMD&#xa0;=&#xa0;-1.89, 95% CI&#xa0;=&#xa0;-2.84 to -0.94). Subgroup analyses indicated greater efficacy for total flavonoids, doses <300&#xa0;mg/kg/day, treatment durations <12 weeks, and female rats. Sensitivity analyses confirmed the robustness of the results. CONCLUSIONS: Rhizoma Drynariae extracts exert significant osteoprotective effects in rat models of osteoporosis by enhancing BMD, trabecular structure, and biomechanical strength. These findings provide preclinical evidence supporting further high-quality clinical studies to determine optimal dosage, treatment duration, safety, and underlying mechanisms.