Current Incidence of Adjacent Segment Pathology Following Lumbar Fusion Versus Motion-Preserving Procedures: a Systematic Review and Meta-Analysis of Recent Projections

BACKGROUND CONTEXT Lumbar fusion has shown to be an effective surgical management option when indicated, improving patient outcomes and functional status. However, concerns of adjacent segment pathology (ASP) due to reduced mobility at the operated segment have fostered the emergence of motion-preserving procedures (MPP). PURPOSE To assess rates of radiographic adjacent segment degeneration (ASDeg) and symptomatic adjacent segment disease (ASDis) as well as reoperation rates due to ASP in patients who have undergone lumbar fusion compared to motion-preservation for degenerative disorders. STUDY DESIGN Systematic Review and Meta-Analysis. METHODS Following PRISMA guidelines, a systematic review and meta-analysis was conducted to find current (1/2012–12/2019) retrospective cohort studies and randomized controlled trials evaluating rates of ASDeg, ASDis, and reoperations due to lumbar ASP. RESULTS A total of 1,751 patients (791 underwent fusion surgery and 960 motion-preserving procedures) in 19 publications were included in the final analysis. Overall incidence rates of ASDeg, ASDis, and reoperation rates were 27.8%, 7.6%, and 4.6%, respectively. Results showed no significant difference between the lumbar fusion versus MPP cohorts in incidence of ASDeg (36.4% vs. 19.2%, p: 0.06), ASDis (10.7% vs. 4.42%, p: 0.25), or reoperation due to ASP (7.40% vs. 1.80%, p: 0.19). Fixed-effects analysis revealed patients who underwent MPP had significantly lower odds of ASDeg (OR: 2.57, CI: 1.95, 3.35, p<.05) and reoperations (OR: 3.18, CI: 1.63, 6.21, p<.05) compared to lumbar fusion patients. CONCLUSIONS This meta-analysis revealed no statistically significant difference in incidence of ASDeg, ASDis, or reoperations due to ASP for patients after lumbar fusion versus MPP. Weighted analysis, however, showed that MPP patients had significantly lower odds of ASDeg and reoperations due to ASP. While previous studies have established the biomechanical efficacy of MPP on cadaveric models, further high-quality studies are required to evaluate the long-term consequences of these procedures on patient-reported outcomes, postoperative complications, and associated inpatient/outpatient costs.