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

Background Low bone density may increase complication risk following revision total shoulder arthroplasty (TSA), but the magnitude and time course of this risk in the revision setting have not been well characterized, with few studies reporting short- or mid-term outcomes. This study compared 90-day and 2-year outcomes after revision TSA in patients with and without a documented diagnosis of low bone density. Methods We performed a retrospective cohort study including patients from January 1, 2005 through February 1, 2024. Low bone density was defined by a documented diagnosis of osteoporosis or osteopenia (ICD-10 M80, M81, or M85.8) present at the time of the index revision. Adult patients undergoing revision TSA with a diagnosis of low bone density were matched to patients without such a diagnosis on demographics, comorbidities, and revision indication, so that documented low bone density was the only variable differing between cohorts. Ninety-day postoperative outcomes and 2-year surgical outcomes were evaluated. Subgroup 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 low bone density was associated with higher rates of periprosthetic fracture (7.2% vs 5.2%; RR 1.37, P=0.028) and hospital readmission (24.6% vs 17.9%; RR 1.38, P < 0.001). At 2 years, periprosthetic fracture remained significantly higher in the low bone density cohort (11.2% vs 8.7%; RR 1.29, P=0.021), while mechanical loosening, dislocation, periprosthetic joint infection, and re-revision were not significantly different. In the osteoporosis subgroup (n = 963 per cohort), osteoporosis was associated with increased 2-year periprosthetic fracture risk (12.5% vs 9.0%; RR 1.38, P=0.015). The osteopenia subgroup (n = 640 per cohort) did not demonstrate a significant difference (9.8% vs 8.9%; RR 1.11, P=0.565). Conclusion A documented diagnosis of low bone density is associated with higher rates of periprosthetic fracture following revision TSA. Subgroup 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 revision TSA.