Low bone density and post-operative outcomes following revision total shoulder arthroplasty.

Background: Low bone density (LBD) may increase complication risk following revision total shoulder arthroplasty (rTSA), but the magnitude and time course of this risk in the revision setting have not been well characterized, with few studies reporting short-term or midterm outcomes. This study compared 90-day and 2-year outcomes after rTSA in patients with and without a documented diagnosis of LBD. Methods: We performed a retrospective cohort study including patients from January 1, 2005, through February 1, 2024. LBD was defined by a documented diagnosis of osteoporosis or osteopenia (International Classification of Diseases, Tenth Revision M80, M81, or M85.8) present at the time of the index revision. Adult patients undergoing rTSA with a diagnosis of LBD were matched to patients without such a diagnosis on demographics, comorbidities, and revision indication, so that documented LBD was the only variable differing between cohorts. Ninety-day post-operative outcomes and 2-year surgical outcomes were evaluated. Sub-group analyses assessed outcomes separately for osteoporosis and osteopenia cohorts. Relative risks with 95% confidence intervals were calculated. Results: After matching, 1,495 patients per cohort were included. At 90 days, a diagnosis of LBD was associated with higher rates of periprosthetic fracture (7.2% vs. 5.2%; relative risk (RR) 1.37, Conclusion: A documented diagnosis of LBD is associated with higher rates of periprosthetic fracture following rTSA. Sub-group analysis suggests that this association is primarily driven by patients with osteoporosis, whereas osteopenia alone was not associated with increased fracture risk. These findings highlight the importance of bone health characterization when evaluating risk profiles in patients undergoing rTSA.