Posterior Lumbar Interbody Fusion with 3D-Navigation Guided Cortical Bone Trajectory Screws for L4/5 Degenerative Spondylolisthesis: 1-Year Clinical and Radiographic Outcomes Ibrahim Hussain 1 , Michael S. Virk 1 , Thomas W. Link 1 , Apostolos J. Tsiouris 2 , Eric Elowitz 1 - OBJECTIVE: We describe our technique and evaluate clinical and radiographic outcomes for patients undergoing L4/5 posterior lumbar interbody fusion with 3D-navigation guided cortical bone trajectory screws (PLIF-CBT) for grade 1 or 2 degenerative spondylolisthesis with a minimum follow- up time of 12 months. - METHODS: A single-institution series of 18 patients was evaluated with data prospectively collected and retrospec- tively analyzed. Pain and disability scores were collected preoperatively and at a minimum of 12 months postoperatively, including back and bilateral leg pain visual analog scores (VAS) and Oswestry Disability Index (ODI) scores. Radio- graphic fusion was assessed as complete, partial, or none based on the presence of bridging bones across the disc space, posterior elements, or both. - RESULTS: Patients demonstrated statistically significant reductions in back pain VAS (P [ 0.0025), leg pain VAS (P < 0.0001), and ODI (P < 0.0001) at a minimum of 12 months postoperatively. Radiographic fusion at an average of 14.9 months postoperatively was available for 16/18 patients, with 6 patients demonstrating fusion (4/6 with complete fusion; 2/6 with partial fusion). There were no instances of intraoperative complications or delayed complications requiring subsequent interventions. - CONCLUSIONS: PLIF-CBT can be performed in a safe and reproducible fashion with excellent clinical outcomes at 1 year postoperatively. The outcomes did not correlate with fusion status, which was unexpectedly low at 37.5% without significant hardware abnormalities necessitating reopera- tions. PLIF-CBT offers several perioperative advantages compared with traditional open PLIF and requires longer- term studies to demonstrate its durability with regard to improvement in clinical pain and radiographic endpoints, including anterior and/or posterior element fusion. INTRODUCTION S pinal fusion for lumbar degenerative spondylolisthesis has demonstrated durable benefits with regard to patient- reported outcomes and healthcare cost-effectiveness standpoints. 1-5 Affecting 6% of the population, 6 this pathologic condition usually arises from a combination of degenerative disc disease, facet arthropathy, and pars interarticularis abnormalities. The combination of foraminal and central canal stenosis can lead to symptoms of radiculopathy and neurogenic claudication. Patients with significant symptoms in whom conservative management is unsuccessful, including physical therapy, oral medications, and epidural steroid injections, often meet the criteria for surgical intervention. Anterior and lateral approaches for lumbar fusion have proved optimal in patients with certain anatomic and global alignment factors; however, the posterior approach remains the most commonly used and time-tested. 7-12 Ralph Cloward first described Key words - 3D navigation - Cortical bone trajectory - Pedicle screws - Posterior lumbar interbody fusion - Spondylolisthesis Abbreviations and Acronyms BMI: Body mass index iCT : Intraoperative computed tomography JOA: Japanese Orthopedic Association Score JOABPEQ: Japanese Orthopedic Association back pain evaluation questionnaire ODI: Oswestry Disability Index PLIF: Posterior lumbar interbody fusion PLIF-CBT : Posterior lumbar interbody fusion with cortical bone trajectory screws SF-36: Short Form Health Survey TLIF: Transforaminal lumbar interbody fusion VAS: Visual analog score From the 1 Weill Cornell Brain and Spine Center, Department of Neurological Surgery, and 2 Department of Neuroradiology, Weill Cornell Medicine, New York-Presbyterian Hospital, New York, New York, USA To whom correspondence should be addressed: Eric Elowitz, M.D. [E-mail: ere2006@med.cornell.edu] Citation: World Neurosurg. (2017). https://doi.org/10.1016/j.wneu.2017.11.034 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2017 Elsevier Inc. All rights reserved. WORLD NEUROSURGERY -: -- -, - 2017 www.WORLDNEUROSURGERY.org E1 Original Article