Assessment of Bone Quality Using Radiogrammetric Parameters of Proximal Humerus in India: Defining the Osteoporotic Fracture Risk Limit Value and its Reliability.

Abstract

World health organization (WHO) has defined osteoporosis clinically on the basis of bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA) scan and the presence of fractures. This facility is expensive and not readily available in majority of the centers in India. The authors have attempted to study defined measurements on radiographs (radiogrammetric parameters) to diagnose osteoporosis in Indian population. We prospectively studied 200 proximal humerus radiographs for measuring radiogrammetric parameters and divided into Group A and B (N = 100 in each group). Group A involved patients with age < 50years and without any illness affecting bone quality. Group B involved patients with age > 50years and sustained acute osteoporotic fractures of distal radius/ anterior wedge vertebral fracture/intertrochanteric fracture following trivial trauma. Three parameters (cortical thickness, cortical index and deltoid tuberosity index) were measured by 3 observers at 2 different occasions. The mean age of patients was 37.87years and 58.38years for group A and B, respectively. The 'cortical thickness' of the proximal humerus diaphysis had the mean value for Group A and B to be 0.4 ± 0.07cm and 0.33 ± 0.06cm respectively. The mean values for the 'cortical index' of proximal humerus came out to be 0.4 ± 0.07 for group A and 0.32 ± 0.06 for group B. The 'deltoid tuberosity index' measurements showed the mean values for group A and B were 1.81 ± 0.23 and 1.55 ± 0.16, respectively. Inter-observer reliability for single measures was excellent for deltoid tuberosity index (ICC 0.8077) and good for cortical thickness (ICC 0.7032) and cortical index (ICC 0.7357). Observer 1 had excellent intra-observer reliabilities for all the three parameters. Observer 2 and 3 had excellent reliability for deltoid tuberosity index and good intra-observer reliability for cortical thickness and cortical index. The cortical thickness had a cut off of ≤ 0.372cm with a sensitivity of 86.02 and specificity of 82.12. The cortical index had a cut off of ≤ 0.378 with a sensitivity of 89.16 and specificity of 84.22. The deltoid tuberosity index had a cut off of ≤ 1.684 with a sensitivity of 96.61 and specificity of 84.08. The outcome of this study is likely to help in early diagnosis of osteoporosis at the community level in the absence of DXA scan as it identifies threshold values for radiogrammetric parameters which can be a predictor of the osteoporosis. The deltoid tuberosity index was found to be the most suitable of these parameters.