Robotic-assisted midline lumbar interbody fusion for the treatment of degenerative lumbar spinal stenosis: a prospective, randomized, controlled, non-inferiority clinical trial protocol

Background: Degenerative lumbar spinal stenosis (DLSS) is a leading cause of low back and leg pain in the elderly. While conventional posterior lumbar interbody fusion (PLIF) is effective, it remains associated with significant tissue trauma and a relatively high incidence of chronic postoperative low back pain, even when empowered by current robotic-assisted technologies. Existing evidence suggests that robotic-assisted midline lumbar interbody fusion with cortical bone trajectory (RA-MIDLIF-CBT) may offer advantages in terms of minimal invasiveness. However, there is a lack of high-quality evidence regarding its non-inferiority in efficacy compared to the equally robotic-assisted PLIF technique, as well as its potential for enhancing accelerated recovery after surgery. Methods: A single-center, prospective, randomized controlled, non-inferiority trial will be conducted. Seventy-four patients aged 60-80 years with single-level DLSS refractory to conservative treatment and meeting definitive criteria for lumbar interbody fusion will be enrolled and randomly assigned (1:1 ratio) to either Group A (control): Robot-assisted PLIF with pedicle screw fixation, or Group B (experimental): Robot-assisted MIDLIF-CBT. The primary outcome measure is the Oswestry Disability Index (ODI). Secondary outcomes include Visual Analog Scale (VAS) scores for low back pain and leg pain, Japanese Orthopaedic Association (JOA) score, operative time, intraoperative blood loss, radiation exposure, screw placement accuracy, compliance with enhanced recovery after surgery (ERAS) protocols, and health economic parameters. Patients will be followed up for 12 months postoperatively. Discussion: This study will be the first to provide high-level evidence on the non-inferiority of RA-MIDLIF-CBT compared to robot-assisted PLIF for treating DLSS. Leveraging the foundational platform of robotic assistance, the findings have the potential to establish RA-MIDLIF-CBT as a novel fusion technique that balances minimal invasiveness, safety, and cost-effectiveness. Additionally, the results will contribute evidence-based support for optimizing ERAS pathways in geriatric spine surgery. Trial Registration: The trial protocol was registered at Chinese Clinical Trial Registry (www.chictr.org.cn, Registration Number: ChiCTR2500095896).