SYSTEMES ET METHODES PERMETTANT DE MIEUX ACCEDER AU CORPS VERTEBRAUX POUR CYPHOPLASTIE, VERTEBROPLASTIE, BIOPSIE DE CORPS VERTEBRAUX OU MISE EN PLACE DE VIS
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.
