Patient-Reported Outcome Measures Plateau 6 Months After Cervical Surgery With Interbody Devices: A Systematic Review of 3271 Patients

Study Design: Systematic review and meta-analysis. Objective: This study aimed to (1) characterize early postoperative improvements in PROMs after cervical interbody surgery; (2) determine whether PROMs demonstrate clinically meaningful change beyond six months; and (3) assess whether anterior cervical discectomy and fusion (ACDF) or cervical disc arthroplasty (CDA) share similar long-term PROM trajectories. Background: Although substantial early postoperative improvement is well-documented in anterior cervical spine surgery, long-term trajectory of patient-reported outcome measures (PROMs) in cervical interbody procedures remains incompletely understood. Methods: A systematic review utilizing PubMed, Embase, Scopus, Web of Science, and the Cochrane Library was used to identify randomized controlled trials or prospective/retrospective cohort studies of ACDF/CDA from 2009 to 2025 reporting PROMs including the Neck Disability Index (NDI), Visual Analog Scale (VAS)-Arm or VAS-Neck. Minimum length of complete postoperative follow-up was two years, and studies reporting outcomes past seven years were excluded. PROM data were extracted and weighted averages were calculated across 17 studies, resulting in trajectories that were compared with established minimal clinically important difference (MCID) values. Results: Pooled analyses of 3271 patients across 17 studies demonstrated rapid early postoperative improvement across all PROMs. Mean NDI decreased from 53.6 preoperatively to 16.9 on a 100-point scale at three months postoperatively, VAS-Neck from 51.7 to 16.5 on a 100-point scale, and VAS-Arm from 40.3 to 9.3 on a 100-point scale. After six months, additional gains were stable to 60 to 84 months across all PROMs, defined by variation not exceeding the respective established MCID thresholds. Both ACDF and CDA demonstrated similar long-term PROM convergence. Conclusions: PROMs improved significantly postoperatively for both ACDF/CDA, plateauing at six months and persisting through seven years postoperatively. Routine collection of PROMs beyond this early postoperative window may offer limited value for evaluating long-term outcomes or device performance.