Study Design.: Retrospective review of a multi-institutional data registry. Objective.: The authors sought to determine the association between age and complications & patient-reported outcomes (PRO) in patients undergoing multilevel transforaminal interbody lumbar fusion (MTLIF). Summary of Background Data.: Elderly patients undergoing MTLIF are considered high risk. However, data on complications and PRO are lacking. Additionally, safety of multilevel lumbar fusion in the elderly remains uncertain. Methods.: Patients ≥50-year-old who underwent MTLIF for degenerative lumbar spine conditions were analyzed. Ninety-day complications and PROs (baseline, 90-d, 1-y, 2-y) were queried using the MSSIC database. PROs were measured by back & leg visual analog scale (VAS), Patient-reported Outcomes Measurement Information System (PROMIS), EuroQol-5D (EQ-5D), and North American Spine Society (NASS) Patient Satisfaction Index. Univariate analyses were used to compare among elderly and complication cohorts. Generalized estimating equation (GEE) was used to identify predictors of complications and PROs. Results.: A total of 3120 patients analyzed with 961 (31%) ≥ 70-y-o and 2159 (69%) between 50–69. A higher proportion of elderly experienced postoperative complications (P = .003) including urinary retention (P = <.001) and urinary tract infection (P = .002). Multivariate analysis demonstrated that age was not independently associated with complications. Number of operative levels was associated with any (P = .001) and minor (P = .002) complication. Incurring a complication was independently associated with worse leg VAS and PROMIS scores (P = <.001). Preoperative independent ambulation was independently associated with improved PROMIS, and EQ5D (P = <.001). Within the elderly, preoperative independent ambulation and lower BMI were associated with improved PROMIS (P = <.001). Complications had no significant effect on PROs in the elderly. Conclusions.: Age was not associated with complications nor predictive of functional outcomes in patients who underwent MTLIF. Age alone, therefore, may not be an appropriate surrogate for risk. Furthermore, baseline preoperative independent ambulation was associated with better clinical outcomes and should be considered during preoperative surgical counseling. Level of Evidence: 3

Study Design.: This was a single-institute retrospective study. Objective.: To describe perioperative and postoperative complications in elderly who underwent multilevel minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) while identifying predictors of complications. Summary of Background Data.: The number of elderly patients undergoing spinal fusion is rising. Spinal surgery in the elderly is considered high risk with high rates of complications. Perioperative and postoperative complications in elderly undergoing multilevel MIS TLIF is, however, not known. Methods.: A retrospective analysis was performed on 467 consecutive patients who underwent multilevel MIS TLIF at a single institution from 2013 to 2017. Two cohorts, 70 years or older and 50 to 69 years old were analyzed. Multiple logistic regressions with minor and major complication rates as the dependent variables were performed to identify predictors of complication based on previously cited risk factors. A p-value of 0.008 or less was considered significant. Results.: One hundred fifty-two elderly and 315 nonelderly patients underwent multilevel MIS TLIFs. The average age was 76.4 and 60.4 years for the elderly and nonelderly cohorts. We observed 13 major (8.44%) and 72 minor (47.4%) complications in the elderly. No difference was noted in complication rates between the cohorts, except for urinary tract infection (P = .004) and urinary retention (P = .014). There were no myocardial infarctions; hardware complications; visceral, vascular, and neural injuries; or death. Length of stay, comorbidity, and length of surgery were predictive of major and minor complications. Conclusion.: Elderly may undergo multilevel MIS TLIF with comparable complication rates. Age was not a predictor of complications. Rather, attention should focus on evaluation of comorbidity and limiting operative times. Level of Evidence: 3

Study Design.: Retrospective review of prospectively collected data at a single institution. Objective.: To compare perioperative and clinical outcomes in morbidly obese patients who underwent minimally invasive transforaminal lumbar interbody fusion (MiTLIF). Summary of Background Data.: Obesity remains a serious public health concern. Obese patients who undergo lumbar fusion have historically thought to be at higher risk for complications and fare worse regarding quality-of-life outcomes. However, recent literature may demonstrate comparable risk and outcomes in obese patients. An increasing number of patients are categorized as morbidly obese (body mass index [BMI] ≥ 40 kg/m²). Perioperative and patient-reported outcomes (PROs) are lacking in this patient population. Methods.: The authors retrospectively reviewed a prospectively collected database of all morbidly obese and non-obese patients that underwent MiTLIF between 2015 and 2018 for degenerative conditions who had minimum 1-year follow-up for outcome assessment. An inverse propensity/probability of treatment weighting was utilized to create a synthetic weighted sample in which covariates were independent of obesity designation to adjust for imbalance between groups. Generalized estimating equations (GEE) was used to estimate the association of morbid obesity and complications and 1-year PROs. Results.: A total of 292 patients were analyzed with 234 non-obese patients and 58 morbidly obese patients. Multivariate analysis failed to demonstrate any association between morbid obesity and achieving minimal clinically important difference (MCID) for Oswestry disability index (ODI), visual analog scale (VAS), or short form-12 (SF-12) physical component score. However, morbid obesity was associated with significant decrease in odds of achieving MCID for SF-12 mental component score (P = 0.001). Increased surgery duration was significantly associated with morbid obesity (P = 0.001). Morbid obesity exhibited no statistically significant association with postoperative complications, readmission, pseudarthrosis, or adjacent segment disease (ASD). Conclusion.: Morbidly obese patients who undergo MiTLIF can achieve meaningful clinical improvement comparable to nonobese patients. Morbid obesity was associated with longer surgical times but was not associated with postoperative complications, readmission, or ASD. Level of Evidence: 3