Study Design. Systematic review and meta-analysis. Objective. To perform a systematic review and meta-analysis of previous studies on HbA1c in preoperative risk stratification in patients undergoing spinal procedures and provide an overview of the consensus recommendations. Summary of Background Data. Diabetes mellitus (DM) and hyperglycemia have been shown to be independent risk factors for increased surgical complications. Glycated Hemoglobin A1C (HbA1c), a surrogate for long term glycemic control, is an important preoperative parameter that may be optimized to reduce surgical complications and improve patient-reported outcomes. However, comprehensive systematic reviews on preoperative HbA1c and postoperative outcomes in spine surgery have been limited. Methods. We systematically searched PubMed, EMBASE, Scopus, and Web-of-Science for English-language studies from inception through April 5th, 2022, including references of eligible articles. The search was conducted according to PRISMA guidelines. Only studies in patients undergoing spine surgery with preoperative HbA1c values and postoperative outcomes available were included. Results. A total of 22 articles (18 retrospective cohort studies, 4 prospective observational studies) were identified with level of evidence III or greater. The majority of studies (n=17) found that elevated preoperative HbA1c was associated with inferior outcomes or increased risk of complications. Random-effect meta-analysis demonstrated that patients with preoperative HbA1c >8.0% had increased risk(s) of postoperative complications (RR: 1.85, 95% CI: [1.48, 2.31], P<0.01) and that patients with surgical site infection (SSI) had higher preoperative HbA1c (Mean Difference: 1.49%, 95% CI: [0.11, 2.88], P=0.03). Conclusion. The findings of this study suggest that HbA1c >8.0% is associated with an increased risk of complications. HbA1c was higher by 1.49% on average among patients with SSI when compared to patients who did not experience SSI. These results suggest that elevated HbA1c is associated with less favorable outcomes following spine surgery. Level of Evidence. IV

Study Design. Systematic review and meta-analysis. Objective. To perform a systematic review and meta-analysis investigating the rate of adverse events after spine surgery in patients who underwent bariatric surgery (BS). Summary of Background Data. Obesity is an established risk factor for postoperative complications after spine surgery. BS has been associated with improvements in health in patients with severe obesity. However, it is not known whether undergoing BS before spine surgery is associated with reduced adverse outcomes. Materials and Methods. PubMed, EMBASE, Scopus, and Web-of-Science were systematically searched according to “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” guidelines. The search included indexed terms and text words from database inception to the date of the search (May 27, 2022). Data and estimates were pooled using the Mantel-Haenszel method for random-effects meta-analysis. Risk of bias was assessed using the Joanna Briggs Institute risk of bias tool. The primary outcome was an all-cause complication rate after surgery. Relative risks for surgical and medical complications were assessed. Results. A total of 4 studies comprising 177,273 patients were included. The pooled analysis demonstrated that the all-cause medical complication rate after spine surgery was lower in patients undergoing BS (relative risk: 0.54, 95% CI: 0.39, 0.74, P < 0.01). There was no difference in rates of surgical complications and 30-day hospital readmission rates between the cohort undergoing BS before spine surgery and the cohort that did not. Conclusion. These analyses suggest that obese patients undergoing BS before spine surgery have significantly lower adverse event rates. Future prospective studies are needed to corroborate these findings. Level of Evidence. 4.

Study Design. Systematic review and Meta-analysis. Objective. To compare outcomes and complications profile of laminectomy alone versus laminectomy and fusion for the treatment of degenerative lumbar spondylolisthesis (DLS). Summary of Background Data. Degenerative lumbar spondylolisthesis is a common cause of back pain and functional impairment. DLS is associated with high monetary (up to $100 billion annually in the US) and nonmonetary societal and personal costs. While nonoperative management remains the first-line treatment for DLS, decompressive laminectomy with or without fusion is indicated for the treatment-resistant disease. Methods. We systematically searched PubMed and EMBASE for RCTs and cohort studies from inception through April 14, 2022. Data were pooled using random-effects meta-analysis. The risk of bias was assessed using the Joanna Briggs Institute risk of bias tool. We generated odds ratio and standard mean difference estimates for select parameters. Results. A total of 23 manuscripts were included (n=90,996 patients). Complication rates were higher in patients undergoing laminectomy and fusion compared with laminectomy alone (OR: 1.55, P<0.001). Rates of reoperation were similar between both groups (OR: 0.67, P=0.10). Laminectomy with fusion was associated with a longer duration of surgery (Standard Mean Difference: 2.60, P=0.04) and a longer hospital stay (2.16, P=0.01). Compared with laminectomy alone, the extent of functional improvement in pain and disability was superior in the laminectomy and fusion cohort. Laminectomy with fusion had a greater mean change in ODI (−0.38, P<0.01) compared with laminectomy alone. Laminectomy with fusion was associated with a greater mean change in NRS leg score (−0.11, P=0.04) and NRS back score (−0.45, P<0.01). Conclusion. Compared with laminectomy alone, laminectomy with fusion is associated with greater postoperative improvement in pain and disability, albeit with a longer duration of surgery and hospital stay.

Study Design. Retrospective cohort.Objective. To compare the rate of adjacent segment disease (ASD) in patients undergoing anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF) for the treatment of degenerative stenosis and spondylolisthesis. Summary of Background Data. ALIF and TLIF are frequently used to treat Lumbar stenosis and spondylolisthesis. While both approaches have distinct advantages, it is unclear whether there are any differences in rates of ASD and postoperative complications. Methods. A retrospective cohort study of patients who underwent index 1-3 levels ALIF or TLIF between 2010 and 2022, using the PearlDiver Mariner Database, an all-claims insurance database (120 million patients). Patients with a history of prior lumbar surgery and those undergoing surgery for cancer, trauma, or infection were excluded. Exact 1:1 matching was performed using demographic factors, medical comorbidities, and surgical factors found to be significantly associated with ASD in a linear regression model. The primary outcome was a new diagnosis of ASD within 36 months of index surgery, and secondary outcomes were allcause medical and surgical complications. Results. Exact 1:1 matching resulted in 2 equal groups of 106,451 patients undergoing TLIF and ALIF. The TLIF approach was associated with a lower risk of ASD (RR 0.58, 95% CI 0.56-0.59, P < 0.001) and all-cause medical complications (RR 0.94, 95% CI 0.91-0.98, P = 0.002). All-cause surgical complications were not significantly different between both groups. Conclusion. After 1:1 exact matching to control for confounding variables, this study suggests that for patients with symptomatic degenerative stenosis and spondylolisthesis, a TLIF procedure (compared to ALIF) is associated with a decreased risk of developing ASD within 36 months of index surgery. Future prospective studies are needed to corroborate these findings.

Study Design. Retrospective cohort. Objective. To compare the rates of pseudarthrosis in patients undergoing 1-3 level Transforaminal Lumbar Interbody Fusion (TLIF) procedures between cannabis users and non-cannabis users. Summary of Background Data. Recreational use of cannabis is common, though it remains poorly studied and legally ambiguous in the United States. Patients with back pain may turn to adjunctive use of cannabis to manage their pain. However, the implications of cannabis use on the achievement of bony fusion are not well-characterized. Methods. Patients who underwent 1-3 level TLIF for degenerative disc disease (DDD) or degenerative spondylolisthesis (DS) between 2010-2022 were identified using the PearlDiver Mariner all-claims insurance database. Cannabis users were identified with ICD 10 code F12.90. Patients undergoing surgery for non-degenerative pathologies such as tumors, trauma, or infection were excluded. 1:1 exact matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with pseudarthrosis in a linear regression model. The primary outcome measure was development of pseudarthrosis within 24 months after 1-3 level TLIF. The secondary outcomes were the development of all-cause surgical complications as well as all-cause medical complications. Results. 1:1 exact matching resulted in two equal groups of 1,593 patients who did or did not use cannabis and underwent 1-3 level TLIF. Patients who used cannabis were 80% more likely to experience pseudarthrosis compared to patients who do not (RR 1.816, 95% CI 1.291-2.556, P<0.001). Similarly, cannabis use was associated with significantly higher rates of all-cause surgical complications (RR 2.350, 95% CI 1.399-3.947, P=0.001) and all-cause medical complications (RR 1.934, 95% CI 1.516-2.467, P<0.001). Conclusion. After 1:1 exact matching to control for confounding variables, the findings of this study suggest that cannabis use is associated with higher rates of pseudarthrosis, as well as higher rates of all-cause surgical and all-cause medical complications. Further studies are needed to corroborate our findings. Level of Evidence. III