Retrospective case series demonstrates high diagnostic accuracy of foot radiographs for detecting osteoporosis in older adults, suggesting a viable opportunistic screening strategy.
Key Points
To evaluate whether opportunistic foot radiographs can serve as an effective screening tool for predicting low bone mineral density compared to standard dual-energy X-ray absorptiometry.
Analyzed a retrospective cohort of 89 patients aged 50 years and older who had both a dual-energy X-ray absorptiometry (DXA) scan and an oblique foot radiograph within 1 year.
Calculated the fifth metatarsal index (5MI) to assess cortical thickness and generated receiver operating characteristic curves to determine the optimal threshold for identifying osteoporosis.
Average 5MI measurements progressively declined with worsening bone loss: 52.6% in normal bone mineral density, 44.6% in osteopenia, and 35.2% in osteoporosis.
The optimal 5MI cutoff of 46.8% demonstrated an area under the curve of 0.977, yielding a sensitivity of 93.3% (95% CI, 70.2%-99.7%) and a specificity of 95.0% (95% CI, 76.4%-99.7%) (P < .001).