SYSTEM AND METHODS FOR IMPROVED ACCESS TO VERTEBRAL BODIES FOR KYPHOPLASTY, VERTEBROPLASTY, VERTEBRAL BODY BIOPSY OR SCREW PLACEMENT

摘要

A method of determining the size and/or placement of screws or otherinstruments in pedicles during surgery in a selected spinal area, comprisinggenerating a dimensionally true three-dimensional image of the bony spine inthe selected spinal area; hollowing out the vertebra in the three-dimensionalimage with cortical wall thicknesses selected by a surgeon performing thesurgery; determining the narrowest cross section (isthmus) within eachpedicle; generating a straight line starting at the center of the isthmus andextending inwardly to a point centered within the anterior cortex so that itis positioned concentrically within the pedicle without touching the wallsthereof, the line terminating inside the vertebral body a predetermineddistance from the anterior inner cortical wall and extending outwardly in theopposite direction to penetrate the posterior pedicle cortex; expanding theline concentrically and radially to a cross sectional size that is less thanthat of the isthmus, the line being expanded into a cylinder that stopsgrowing when any portion thereof contacts the inner cortical wall of thehollowed out vertebral body, with the exception of the posterior pediclecortex; and calculating the ideal pedicle screw or instrument diameter, lengthand/or trajectory based on the dimensions and trajectory of the cylindergenerated for each pedicle. Also, a new and improved method for providingaccess to the interior of a pedicle for a desired transpedicular procedure,and a new and improved pedicle cannula construction are disclosed herein.