SpineAssist offers enhanced performance in spinal surgery when compared to free-hand surgeries, by increasing placement accuracy and reducing neurologic risks. In addition, 49% of the cases reported herein used a percutaneous approach, highlighting the contribution of SpineAssist in procedures without anatomic landmarks.

The advantages associated with a robotic guidance system may make the surgeon more at ease about offering minimally invasive or percutaneous surgical options to patients and more comfortable about implementing pedicle-based fixation in general. This advanced technology may also allow inclusion of patients with complicated anatomic deformities, who are often excluded from pedicle screw-based surgery options.

Difficulties encountered with use of the SpineAssist, while minimal, will be described and suggestions made for future improvements.

OBJECTIVE The authors describe a cadaveric analysis to determine the ideal dimensions and trajectory for considering endoscopic transforaminal interbody implantation. METHODS The soft tissues of 8 human cadavers were removed from L-1 to the sacrum, exposing the posterior bony elements. Facetectomies were performed bilaterally at each lumbar level with resection of the pars interarticularis, revealing the pedicles, nerve roots, and interbody disc space. Each level was digitally photographed with a marker for scale and evaluated with digital analysis software. The traversing and exiting nerve roots and pedicle margins were identified, and the distances between these structures and their relationships to the surrounding structures were documented. RESULTS The dimensions of 2 areas were measured: the working triangle and safe zone. The working triangle is the triangle between the exiting and traversing nerve roots above the superior margin of the inferior pedicle. The safe zone is the trapezoid bounded by the widths of the superior and inferior pedicles between the exiting and traversing nerve roots. The mean surface area for the working triangle was 1.83 cm2, with L5–S1 having the largest area at 2.19 cm2. The mean surface area of the safe zone was 1.19 cm2, with L5–S1 having the largest area at 1.26 cm2. At the medial border of the pedicle extending superiorly, there were no nerve structures within 1.19 cm at any level. On the lateral border of the pedicle, the exiting nerve root was closer superiorly, with the closest being 0.3 cm. CONCLUSIONS The working triangle is a relatively large area. The safe zone, just superior to the pedicle, is free of nerve structures. By utilizing the superior border of the pedicle, the disc space can be accessed within this safe zone without risk of injury to the nerves. A thorough understanding of foraminal anatomy is fundamental for considering how to safely access the disc space, thereby utilizing less invasive endoscopic techniques, and is an important first step in considering what shapes and sizes of interbody implants and retractors are feasible for use in the foramen.