Study Design.: Retrospective cohort. Objective.: To compare navigation and robotics in terms of clinical outcomes after minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). Summary of Background Data.: Although robotics has been shown to have advantages like reduced radiation exposure, greater screw size, and slightly better accuracy over navigation, none of the studies has compared these two modalities in terms of clinical outcomes. Methods.: Patients who underwent single-level MI-TLIF using robotics or navigation and had a minimum of 1-year follow-up were included. The robotics and navigation groups were compared for improvement in patient-reported outcome measures (PROMs), minimal clinically important difference, patient-acceptable symptom state, response on the global rating change scale, and screw-related complication and reoperation rates. Results.: A total of 278 patients (143 robotics, 135 navigation) were included. There was no significant difference between the robotics and navigation groups in the baseline demographics, operative variables, and preoperative PROMs. Both groups showed significant improvement in PROMs at below six and six months or above, with no significant difference in the magnitude of improvement between the two groups. Most patients achieved minimal clinically important difference and patient-acceptable symptom state and reported feeling better on the global rating change scale, with no significant difference in the proportions between the robotics and navigation groups. The screw-related complication and reoperation rates also showed no significant difference between the two groups. Conclusions.: Robotics did not seem to lead to significantly better clinical outcomes compared with navigation following MI-TLIF. Although the clinical outcomes may be similar, robotics offers the advantages of reduced radiation exposure, greater screw size, and slightly better accuracy over navigation. These advantages should be considered when determining the utility and cost-effectiveness of robotics in spine surgery. Larger multicenter prospective studies are required in the future to further investigate this subject.

Study Design: Retrospective cohort. Objective: To compare the characteristics of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) metrics when interpreting Neck Disability Index (NDI) following cervical spine surgery. Methods: Patients who underwent primary cervical fusion, discectomy, or laminectomy were included. NDI and global rating change (GRC) data at 6 months/1 year/2 years were analyzed. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MCID and PASS in predicting improvement on GRC were calculated for the overall cohort and separately for patients with minimal (NDI <30), moderate (NDI 30 – 49), and severe (NDI ≥ 50) preoperative disability. Two groups with patients who achieved PASS but not MCID and patients who achieved MCID but not PASS were analyzed. Results: 141 patients (206 responses) were included. PASS had significantly greater sensitivity for the overall cohort (85% vs 73% with MCID, P = .02) and patients with minimal disability (96% vs 53% with MCID, P < .001). MCID had greater sensitivity for patients with severe disability (78% vs 57% with PASS, P = .05). Sensitivity was not significantly different for PASS and MCID in patients with moderate preoperative disability (83% vs 92%, P = .1). 17% of patients achieved PASS but not MCID and 9% of patients achieved MCID but not PASS. Most of these patients still reported improvement with no significant difference between the 2 groups (89% vs 72%, P = .13). Conclusion: PASS and MCID are better metrics for patients with minimal and severe preoperative disability, respectively. Both metrics are equally effective for patients with moderate preoperative disability.

Study Design: Retrospective cohort study. Objective: Frailty is defined as a state of minimal “physiologic reserve.” The modified 5 factor frailty index (mFI-5) is a recently proposed metric for assessing frailty and has been previously studied as a predictor of morbidity and mortality. However, its utility in predicting postoperative patient reported outcomes (PROMs) and return to activities remains understudied. Methods: This is a retrospective cohort study of patients undergoing 1 or 2 level minimally invasive transforaminal lumbar interbody fusion queried from a prospectively maintained multi-surgeon registry. Comorbidities including hypertension, congestive heart failure, diabetes, chronic obstructive pulmonary disease, and functional status were utilized to calculate the mFI-5. Patients were separated into 3 cohorts, “non-frail,” “moderately frail” or “severely frail” based on their mFI-5. Patient outcomes were compared between the cohorts. Results: 392 patients were included of which 227 patients were non-frail, 134 were moderately frail, and 31 were severely frail. Frail patients had longer operative time ( P = 0.002), greater estimated blood loss ( P = 0.038). Despite similar preoperative PROMs, at a longer term follow up, frail patients also had worse PROM scores for ODI ( P = 0.009), VAS-back ( P = 0.028), and VAS-leg ( P = 0.004). Frail patients had worse preoperative ( P = 0.017) and postoperative ( P < 0.001) SF-12 PCS. At 1-year, frail patients had lower rates of fusion ( P = 0.002). Frail patients also demonstrated lower rates of returning to work ( P = 0.018), returning to driving ( P = 0.027), and discontinuation of narcotics ( P = 0.004). Conclusion: Frail patients as measured by the mFI-5 index demonstrated worse postoperative outcomes following 1 or 2 level MI-TLIF. Careful patient selection and preoperative optimization may be especially important in frail patients.

Study Design: Retrospective cohort study. Objective: Decompression for the treatment of lumbar spinal stenosis (LSS) has shown excellent clinical outcomes. In patients with symptomatic single level stenosis and asymptomatic adjacent level disease, it is unknown whether decompressing only the symptomatic level is sufficient. The objective of this study is to compare outcomes between single level and dual level minimally invasive (MIS) decompression in patients with adjacent level stenosis. Methods: The current study is a retrospective review of patients undergoing primary single or dual level MIS decompression for LSS. Radiographic stenosis severity was graded using the Schizas grading. Patients undergoing single level decompression (SLD) with moderate stenosis at the adjacent level were compared with patients undergoing dual level decompression (DLD) for multi-level LSS. Clinical outcomes, complications, and reoperations were compared. Subgroup analysis was performed on patients with the same Schizas grade at the adjacent level in the SLD group and the second surgical level in the DLD group. Results: 148 patients were included (126 SLD, 76 DLD). There were no significant differences in patient reported outcomes between the two groups at any timepoint up to 2 years postoperatively, including in the matched stenosis severity subgroups. Operative time was longer in the DLD cohort ( P < 0.001). There were no significant differences in complications or reoperation rates. Conclusion: In patients with single level symptomatic LSS and adjacent level stenosis, decompression of only the symptomatic level provided equivalent clinical outcomes compared to dual level decompression. The additional operative time and potential incremental risk of dual level surgery may not be justified.