Cortical Bone Trajectory Screws in Posterior Lumbar Interbody Fusion: Minimally Invasive Surgery for Maximal Muscle Sparing-A Prospective Comparative Study with the Traditional Open Technique

Introduction. A prospective comparative study between classical posterior interbody fusion with peduncular screws and the new technique with divergent cortical screws was conducted. Material and Methods. Only patients with monosegmental degenerative disease were recruited into this study. We analyzed a cohort of 40 patients treated from January 2015 to March 2016 divided into 2 groups (20 patients went to traditional open surgery and 20 patients under mini-invasive strategy). Primary endpoints of this study are fusion rate and muscular damage; secondary endpoints analyzed were three different clinical scores (ODI, VAS, and EQ) and the morbidity rate of both techniques. Results. There was no significant difference in fusion rate between the two techniques. In addition, a significant difference inmuscular damage was found according to the MRI evaluation. Clinical outcomes, based on pain intensity, Oswestry Disability Index status, and Euroquality-5D score, were found to be also statistically different, even one year after surgery. This study also demonstrated a correlation between patients' muscular damage and their clinical outcome. Conclusions. Cortical bone trajectory screws would provide similar outcomes compared to pedicle screws in posterior lumbar interbody fusion at one year after surgery, and this technique represents a reasonable alternative to pedicle screws.