Post-hoc analysis of a randomized controlled trial investigating denosumab and alendronate therapy has found that denosumab treatment reduced the size of existing bone erosions in female patients with rheumatoid arthritis (RA). The patients studied were randomly assigned to receive either one subcutaneous injection of denosumab 60 mg (n = 20) or oral alendronate 70mg weekly (n = 20). The width, depth and volume of bone erosions were significantly reduced after 6 months of denosumab treatment (P <0.01), as measured by high-resolution peripheral quantitative CT. By constrast, these measures of bone erosion were significantly increased in alendromate-treated patients after 6 months (P <0.01). Compared with baseline values, the denosumab group also showed significantly increased bone mineral density after 6 months (P <0.05), unlike the alendronate patient group (P = 0.51).