Divergent Bilateral Posterior Lumbar Interbody Fusion with Cortical Screw Fixation: Description of New Trajectory for Interbody Technique from Midline Exposure

BACKGROUND: A major drawback to use of cortical bone trajectory pedicle screws (CBTPSs) with traditional posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion grafts is that traditional graft insertion trajectories require wider posterior exposure. This wider exposure, beyond the limits otherwise required for CBTPS placement, negates a primary benefit of CBTPS fixation. The aim of this study was to define an alternative surgical technique for interbody graft placement that, when used in conjunction with CBTPS fixation, permits both minimal soft tissue dissection and optimal graft placement. METHODS: A team of neurosurgeons specializing in treatment of spinal pathologies developed a surgical technique for insertion of bilateral PLIF grafts that complements the principles of CBTPS fixation. This technique is illustrated in a patient undergoing lumbosacral decompression, CBTPS fixation, and 3-column arthrodesis. RESULTS: The described technique uses a divergent trajectory of bilateral PLIF grafts rather than the traditional parallel or convergent trajectories. CONCLUSIONS: By aiming medially to laterally with the interbody graft, one recapitulates many advantages of CBTPSs, including avoidance of wide tissue dissection, greater intergraft volume available for bone grafting, and greater graft coverage of the hypophyseal ring. The prospective collection of outcome data for patients who undergo lumbosacral fusion using the divergent PLIF technique is ongoing.