Influence of Frailty on Clinical and Radiological Outcomes in Patients Undergoing Transforaminal Lumbar Interbody Fusion—Analysis of a Controlled Cohort of 408 Patients

<b>Background/Objectives</b>: The concept of frailty has been recognized as an important issue which can influence postoperative outcomes. We aimed to investigate the influence of frailty on clinical and radiological outcomes in patients undergoing transforaminal lumbar interbody fusion (TLIF) for degenerative spine disease. <b>Methods</b>: A single-center, retrospective cohort study was conducted involving 408 patients in whom 506 expandable interbody devices were implanted. The patients were grouped into vulnerable/frail versus well/fit according to the Canadian Frailty Index. <b>Results</b>: The frail patients were older and had a larger number of fused segments (3.0 vs. 2.4 segments, <i>p</i> = 0.009). In the univariate analysis, the frail patients were more likely to experience a postoperative adverse event (AE) until discharge (OR 1.89, 95% CI 1.22-2.92; <i>p</i> = 0.004), three (OR 1.57, 1.07-2.3; <i>p</i> = 0.021), and 12 months postoperatively (OR 3.77, 1.96-7.24; <i>p</i> < 0.001). Following the multivariable logistic regression analysis, frailty remained an independent risk factor for postoperative AEs at 12 months (OR 3.44, 95% CI 1.69-6.99; <i>p</i> = 0.001). <b>Conclusions</b>: Frailty negatively influenced the rate of AEs until 12 months, while the odds of having a favorable outcome at any time remained unaffected in patients undergoing posterior spinal fusion with TLIF. Future efforts are needed to evaluate whether preoperative medical optimization or prehabilitation may positively impact patient outcomes.