1569. Evaluation of Estrogen and Menopausal Status on Lumbar Decompression and Fusion: a Retrospective Analysis.

Authors: Dallas Sheinberg; Roberto Perez-Roman, MD; Julian Lugo-pico, MD; Karthik Madhavan, MD; Joseph Gjolaj, MD; Barth Green, MD (Miami, FL)

Introduction: Estrogen plays a major physiologic role in inhibiting bone resorption through indirect inhibition of osteoclast differentiation and promotion of osteoblast differentiation. Extensive bone resorption, ossification, and remodeling at the surgical site is required after spinal fusion in order to produce a strong and biomechanically secure fusion. Hardware fixation is dependent on bone quality and thus the metabolic imbalance present in post-menopausal women may pose risk of pseudoarthrosis/nonunion. Currently, there is no literature comparing fusion rates in women based on menopausal status. Methods: From January 2013 to August 2017, we performed a retrospective comparative analysis of patients who underwent posterior lumbar decompression and fusionat a single institution (JMH).Inclusion criteria were adults (age ≥18 years) with who had underwent lumbar spinal fusion surgery. All surgeries were performed on the patients using a consistent, standard procedure. A total of 80 patients were identified and divided into premenopausal (16 patients) and postmenopausal (64 patients) groups according to whether or not they had undergone menopause prior to the operation. Data on medication regimens before and after surgery was recorded to monitor for use of any hormone replacement therapy. Clinical and radiologic data was assessed at 1-year follow up. Results: There were 5/64 patients (7.8%) in the postmenopausal group that required revision, compared with 0/16 patients (0%) in the premenopausal group. Of the postmenopausal patients requiring revision, 2/5 were receiving perioperative hormone replacement therapy (estrogen or progesterone). Conclusion: The effects of menopausal estrogen deficiency on successful lumbar decompression and fusion rates is previously unreported. Postoperative fusion rates differed based on menopausal status, with an increased incidence of revision surgery required in postmenopausal patients. Considering the limited number of patients in this study, our results need to be validated on a larger number of patients, probably multicenter studies.