Clinical and radiological outcomes comparison of the posterior lumbar interbody fusion with cortical bone trajectory screw fixation (MIDLF) and conventional pedicle screw fixation for low-grade degenerative spondylolisthesis

Abstract

Introduction. Pedicle screw fixation is currently the mainstay technique to promote the lumbar spinal fusion, but it has some important drawbacks, including high surgical morbidity, the risk of superior facet violation, significant dissection and muscle damage, frequent screw loosening, and the increased risk of neurovascular injury. Minimally access surgery techniques have evolved in an attempt to reduce these procedure related complications, the Cortical Bone Trajectory (CBT) being one of the most promising of them. Numerous studies have analyzed the biomechanical features of the CBT screws but few studies have examined clinical outcomes in patients and compared them to the traditional technique. Aim of the study. To compare the effectiveness of the posterior lumbar interbody fusion (PLIF) using the cortical bone trajectory (CBT) and the traditional pedicle screw (PS) fixation techniques. Materials and methods.. We enrolled 112 patients with degenerative low-grade spondylolisthesis and assigned them to one of the 2 surgical groups: CBT-PLIF (MIDLF) or PS-PLIF. The primary outcome measure was the intervertebral fusion rate, evaluated by thin cut 3D CT-scan reconstructions. Secondary outcome measures included: visual analog scale (VAS) for perioperative back and leg pain intensity, Oswestry Disability Index and 12 – Item Short Form Health Survey (SF-12) scores for functional status improvement assessment, overall patient satisfaction, intraoperative muscle damage (serum CK levels), operative time, total incision length, intraoperative blood loss and perioperative complications. The data were collected prospectively between December 2015 and December 2019. Minimal follow-up period was 12 months. Results. There were no significant differences in the fusion rates at the 12 months follow-up points. Also, the improvement in pain VAS score and functional status were similar in both groups. Additionally, the CBT group experienced significantly less blood loss, quickeroperative time, significantly shorter incision length, and lower postoperative serum creatinine kinase levels meaning less intraoperative multifidus muscle damage. Conclusions. Both techniques provided similar clinical outcomes and fusion rates, but the CBT pedicle screw fixation has the additional benefits of a minimal access surgery technique, with less surgical morbidity, less pain and better functional recovery especially early postoperative. We suggest that CBT pedicle screw fixation is a reasonable alternative to the traditional pedicle screw fixation, if used to promote the posterior lumbar interbody fusion.