Does deltoid tuberosity index correlate with bone density in patients undergoing elective arthroscopic shoulder surgery?

Background: Poor bone mineral density (BMD) has been linked with poor healing and outcomes in the operative management of rotator cuff repair. The deltoid tuberosity index (DTI) has shown promise as an affordable and opportunistic indicator of BMD for patients with proximal humerus fractures. DTI could be a useful preoperative screening tool for BMD among patients indicated for rotator cuff repair. This study aims to evaluate whether DTI can be used as a reliable alternative to dual-energy x-ray absorptiometry (DEXA) for approximating BMD in patients undergoing shoulder arthroscopy. Methods: A retrospective chart review was conducted on patients undergoing shoulder arthroscopy who had previously had a DEXA scan and had an x-ray of the shoulder done within one year of the DEXA scan. DEXA T-scores and density values of the spine and femoral neck were collected from patient medical records and compared to cortical measurements from radiographs of the shoulder used to calculate DTI. Regression analysis was performed to compare DTI to DEXA T-scores and DEXA BMD of the spine and femoral neck. Inter-rater and intrarater repeatability were also assessed using intraclass correlation coefficients. Results: 134 patients (115 female and 19 male) were included with an average age of 69 years. For DTI measurements, intraclass correlation coefficient values were 0.94 (95% CI, 0.85 to .98) for intrarater and 0.88 (95% CI, 0.77 to 0.95) for inter-rater reliability. Regression analysis showed a weak positive correlation between DTI and DEXA T-scores of the femoral neck (r = 0.29, Conclusion: DTI only weakly correlates with DEXA T-scores and BMD measurements for patients undergoing shoulder arthroscopy. DTI may not be a reliable screening tool for BMD in these patients and should be relied upon with caution outside of application to osteopenic fracture patients.