Patent ID: 8936626
Filing Date: 2015-01-20
Classification: A61B

Abstract:
1. A method for bi-cortical screw fixation in a vertebrae comprising the steps of: inserting a guidewire into a pre-determined location in a pedicle defining an initial surgical path; advancing one or more inner dilators over said guidewire down to the bone surface of the pedicle to expand soft tissues surrounding said guidewire; advancing over the one or more inner dilators a final dilator having an lumen sized to pass a minimally invasive pedicle screw; removing at least one of the one or more inner dilators; advancing a probe through the final dilator and any remaining inner dilators, the probe having a blunt tip and a visual reference scale for reading against a visual reference located on at least one of the final dilator and a remaining inner dilator, the blunt tip of the probe being advanced through the pedicle and cancellous bone of the vertebral body to create a guide hole until said blunt leading end of the probe contacts the anterior cortical wall of the vertebrae; establishing a fixed trajectory aligned with the guide hole formed by the advancement of the blunt tip of the probe through the vertebral body by fixing the position of said final dilator while said probe is still in positioned within said guide hole; determining a depth of the vertebra by comparing the visual reference scale on the probe against the visual reference located on the final dilator or remaining inner dilator; removing the guidewire and blunt tip probe from surgical site and inserting a bone tap through the final dilator along the fixed trajectory and tapping the guide hole while monitoring for breach of the pedicle wall with a neuromonitoring system coupled to the tap, the bone tap having a depth stop set to a predetermined depth based on the determined depth of the vertebra removing bone tap and all dilators except final dilator from surgical path; advancing pedicle screw of a length selected based upon the determined depth of the vertebra down the tapped guide hole such that a distal end of the screw is seated in the anterior cortical bone of vertebrae.