Second Metacarpal Cortical Index Correctly Predicts Osteoporosis

Background: Second metacarpal index (2MCI) is a quick and simple calculation obtained from hand or wrist radiographs that can be used to screen for osteoporosis and target high-risk patients. In this study, we investigate the relationship between the 2MCI and hip bone mineral density. Materials and Methods: We conducted a retrospective review of 1,080 patients aged 18 to 100 years who received a dual-energy x-ray absorptiometry (DEXA) scan between January 1, 2004, and March 1, 2024, and had a hand or wrist radiograph within 1 year of their scan. Patients were excluded if the second metacarpal could not clearly be seen on radiographs or if there was no mention of the femoral neck T-score. Multivariable logistic regression and Pearson correlation analyses were performed. Results: A total of 1,028 patients were included. Pearson correlation analysis demonstrated a moderate correlation between 2MCI and femoral neck T-score (R = .40, P < .001). Stratification by age, sex, and days between scans demonstrated a minor modifier effect. The mean time between hand radiographs and DEXA scans was 134 days ± 107 days. The mean 2MCI was 0.56 ± 0.11 (range, 0.21–0.94). The mean femoral neck T-score was −1.6 ± 1.1 (range, −4.9 to 3.2). The area under the curve, sensitivity, and specificity of 2MCI for osteoporosis with a threshold value of 0.57 were 0.833, 82.2%, and 72.4%, respectively. Conclusion: Using the 2MCI offers a straightforward approach for osteoporosis screening, requiring minimal time and no complex calculations. Although DEXA scans remain the gold standard for diagnosing osteoporosis, this measurement may help orthopedic surgeons identify patients who should be referred for further assessment.