Reliability and diagnostic performance of radiologic indices of the proximal humerus in evaluating bone mineral density: a retrospective study

Abstract

Proximal humerus fractures (PHFs) are the third most common osteoporotic fractures. Assessment of bone mineral density (BMD) is clinically relevant in patients with PHFs. Several studies have proposed the use of radiologic indices, including the average cortical bone thickness (CBTA), gauge cortical bone thickness, medial cortical ratio, and deltoid tuberosity index (DTI), to assess local BMD in patients with PHFs. In this study, we aimed to assess the reliability of these radiologic indices and determine their diagnostic performance for identifying DXA-defined osteoporosis. We retrospectively included 145 individuals who underwent anteroposterior shoulder radiography and dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine in our hospital between January 2021 and June 2023. Two independent researchers measured the radiologic indices using the shoulder X-ray. The DXA was used to assess BMD. The intra- and inter-observer reliabilities of the four radiologic indices were good to excellent (ICC = 0.806–0.963). The CBTA demonstrated moderate associations with DXA-derived BMD parameters ( r = 0.439–0.517, P < 0.001), DTI also exhibited weak to moderate associations across the examined anatomical sites ( r = 0.380–0.500, P < 0.001). Receiver operating characteristic curve analysis demonstrated that the areas under the curve of CBTA and DTI for identifying DXA-defined osteoporosis were 0.844 and 0.842, with optimal cut-off values of 5.71 and 1.38, respectively. CBTA and DTI showed good measurement reliability and moderate associations with DXA-derived BMD parameters. They may provide supplementary radiologic information on low BMD risk from routine shoulder radiographs and may help identify patients who warrant further DXA evaluation. Not applicable.