Rate and mode of screw misplacements after 3D-fluoroscopy navigation-assisted insertion and 3D-imaging control of 1547 pedicle screws in spinal levels T10-S1 related to vertebrae and spinal sections.

Abstract

In the field of spinal surgery, 3D-fluoroscopy navigation-assisted pedicle screw (PS) insertion with intra-operative 3D-image control represents a modern application of contemporary navigation technology. In literature, sectional or vertebral accuracy limitations of this image-guidance approach are not profoundly specified. This observational study explicitly differentiates accuracy rates and misplacement mode between spinal sections and single vertebrae from T10 to S1 using a navigation-assisted approach. From February 2011 through July 2015, all 3D-fluoroscopy navigation-assisted, 3D-image controlled PS insertions from T10 to S1 were prospectively recorded and evaluated for PS insertion depth, angulation, and entering-point modifications after intraoperative O-arm control scanning. Major complications requiring revision surgery for neurological damage/major bleedings, and procedure-related unintended violations of anatomical structures were recorded. In 1547 navigation-assisted PS insertions, thoracolumbar accuracy (96.4%) was significantly higher than sacral accuracy (92.6%, p≈0.007) due to special requirements to exact PS (insertion depth) in S1 (p<0.001). Vertebrae with modification rates above average were identified (T10, L5-S1) (p<0.001). Major complications did not occur, anatomical structures were violated in 1.2% (19/1547 PS insertions). In navigation-assisted O-arm-controlled PS placements, correct PS insertion depths are less easily to achieve than correct trajectory or entering-points, which is important for bicortical PS anchorage in S1. Therefore, post-instrumentation PS control by 3D-imaging or at least intraoperative fluoroscopy is recommended for levels with special requirements to exact PS insertion depths (e.g. S1).