BACKGROUND: Following wrist fracture, it is desirable to identify patients with osteoporosis. A smartphone-based application (BoneGauge) that uses second metacarpal cortical thickness ratio (2MCP) measured on X-ray has been proposed. This study aims to validate this application using dual-energy X-ray absorptiometry scan in a cohort of patients with distal radius fractures. METHODS: Thirty subjects aged 50 and over who sustained low-energy fractures of the radius were recruited and measurements were completed by two independent observers using the application. RESULTS: The interrater reliability as a screening tool was insufficient (κ = 0.61). Using the 2MCP threshold of 60% for detection of osteopaenia or osteoporosis, we found insufficient correlation between the dual-energy X-ray absorptiometry scan and the two sets of readings using the application (κ = 0.28 and 0.35, respectively). CONCLUSION: On the basis of these results, 2MCP of 60% is not sensitive enough to be used as a screening tool via a smartphone application for assessment of osteoporosis risk.