Double tubular minimally invasive spine surgery: a novel technique expands the surgical visual field during resection of intradural pathologies

OBJECTIVE A major challenge of a minimally invasive spinal approach (MIS) is maintaining freedom of maneuverability through small operative corridors. Unfortunately, during tubular resection of intradural pathologies, the durotomy and its accompanying tenting sutures offer a smaller operating window than the maximum surface of the tube's base. The objective of this study was to evaluate if a novel double tubular technique could expand the surgical visual field during MIS resection of intradural pathologies. METHODS A total of 25 MIS resections of intradural extramedullary pathologies were included. A posterior tubular interlaminar fenestration was performed in all surgeries. A durotomy covering the whole diameter of the tubular base was the standard in all cases. After placement of two tenting sutures on each side of the durotomy and application of tension, the resulting surface of the achieved dura fenestration was measured after optical analysis of the intraoperative video. In the next step, a second tube, 2 mm thinner than and the same length as the first, was inserted telescopically into the first tube, resulting an angulated fulcrum effect on the tenting sutures. RESULTS Optical surface analysis of the dura fenestration before and after the second tubular insertion verified a significant widening of the visual field of 43.1% (mean 18.84 mm(2), 95% CI 16.8-20.8, p value < 0.001). There were no ruptured tenting sutures through the increased tension. Postoperative MRIs verified complete resection of the pathologies. CONCLUSIONS Inserting a second tube telescopically during posterior minimally invasive tubular spinal intradural surgery leads to an angulated fulcrum effect on the dura tenting sutures which consequently increases the surface of the dura fenestration and induces a meaningful widening of the visual field.