SUN-789 - Comparative Effectiveness of Anti-Resorptive and Anabolic Therapies for Prevention of Hardware Failure and Reoperation in Osteoporotic Adult Patients Undergoing Posterior Spinal Fusion

Background: Osteoporosis increases surgical complication risk in patients requiring spinal fusion. While several small retrospective studies suggest anabolic therapies (teriparatide, abaloparatide, romosozumab) demonstrate superior outcomes compared to antiresorptive agents (bisphosphonates, denosumab), these studies have limited sample sizes, confounded control groups, or administered only low dose bisphosphonates. Equipoise remains regarding optimal perioperative osteoporosis management.

Methods: We conducted a retrospective cohort study leveraging the University of California (UC) Data Warehouse, a repository of de-identified patient records spanning multiple UC health campuses. We included patients aged 50 with osteoporosis (ICD-10 code or DEXA T-score < -2.5) who underwent posterior thoracolumbar spinal fusions from 2013 to 2024. We excluded patients with surgical indications related to malignancy, trauma, or osteomyelitis. Patients were categorized based on receipt of anabolic versus antiresorptive therapy within 1 year pre-operatively through 2 years post-operatively. The primary outcome was a composite of hardware removal or reoperation within 2 years.

Results: We identified 1,058 patients with osteoporosis who underwent posterior thoracolumbar spinal fusions from 2013 to 2024 and received osteoporosis pharmacotherapy: 659 patients who received anabolic therapy and 399 who received antiresorptive therapy. The composite outcome of hardware removal or reoperation within 2 years occurred in 126 anabolic-treated patients (19%) and 52 antiresorptive-treated patients (13%). In unadjusted analysis, anabolic therapy was associated with increased odds of hardware removal or reoperation (OR 1.58, 95% CI 1.12-2.24, p=0.009).

Conclusions: In this cohort, which is among the largest to examine osteoporosis therapy in spinal fusion outcomes, antiresorptive agents were associated with lower complication rates compared to anabolic therapies, contrary to prior smaller studies. These findings may challenge current assumptions and suggests bisphosphonates, which are more accessible and affordable, may have benefit for perioperative management. However, our reliance on hardware removal and reoperation as surrogate endpoints represents a key limitation as the database structure precluded assessment of spinal fusion, the gold standard surgical outcome. Prospective randomized trials are needed to adjudicate these findings.

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