Testosterone replacement therapy increases 2 and 5 year reoperation rates after posterior lumbar fusion: a propensity-matched analysis of 1808 surgical patients

BACKGROUND: Testosterone replacement therapy (TRT) use has increased substantially in recent years, yet its impact on outcomes following posterior lumbar fusion remains unclear. Given testosterone's known effects on bone metabolism, coagulation, and musculoskeletal physiology, understanding its relationship with postoperative complications and long-term reoperation is critical for perioperative risk stratification. This study evaluates the association between preoperative TRT use and short- and long-term outcomes following posterior lumbar fusion. METHODS: A retrospective cohort study was conducted using the PearlDiver Mariner165 database (2010-2020). Adult male patients undergoing posterior lumbar fusion were identified using CPT codes and stratified by preoperative TRT use, defined as ≥3 months of therapy with ≥2 prescriptions. Patients with major systemic or neurologic diseases were excluded. TRT and non-TRT cohorts were matched 1:1 using propensity scores based on age, Charlson Comorbidity Index (CCI), diabetes, and tobacco use. Outcomes included 90-day postoperative complications and reoperation rates at 2 and 5 years. Multivariable logistic regression was performed adjusting for relevant comorbidities. RESULTS: A total of 5068 patients were identified, including 955 TRT users. After propensity matching, 904 well-balanced pairs were analyzed. There were no significant differences in 90-day complications between cohorts, including acute kidney injury, thromboembolic events, surgical site complications, readmissions, or persistent pain (all p > 0.05). However, TRT use was independently associated with increased long-term reoperation risk. On multivariable analysis, TRT patients demonstrated higher odds of reoperation at 2 years (adjusted OR 2.36, 95% CI 1.78-3.12, p < 0.001) and 5 years (adjusted OR 2.18, 95% CI 1.70-2.80, p = 0.005). CONCLUSIONS: Preoperative TRT use was not associated with increased short-term postoperative complications following posterior lumbar fusion but was independently associated with a significantly higher risk of long-term reoperation. These findings suggest that TRT may serve as a marker for patients with more complex postoperative trajectories rather than directly increasing perioperative risk. While TRT should not be considered a contraindication to surgery, its presence may warrant closer longitudinal surveillance and more nuanced preoperative counseling regarding long-term expectations. Further prospective studies incorporating radiographic and hormonal data are needed to clarify underlying mechanisms.