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Pedicle screw extension for use in percutaneous spinal fixation

  • US 8,845,640 B2
  • Filed: 06/18/2010
  • Issued: 09/30/2014
  • Est. Priority Date: 06/18/2010
  • Status: Active Grant
First Claim
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1. A bone screw extension assembly for use in placing a connecting rod percutaneously into tissue of a patient, comprising:

  • a multi-axial bone screw including a shaft having a threaded screw portion and a yoke articulatingly attached to said shaft, said yoke having an exterior surface and a slot therethrough for receiving a connecting rod, said slot defined by a pair of upstanding arms having opposed interior surfaces, said yoke including an extension coupling surface and a first holding surface on a side surface of said yoke;

    a screw extension releasably coupled to said yoke of said bone screw, said screw extension including an elongate hollow outer sleeve having a distal end and a proximal end and an elongate hollow inner sleeve disposed within said outer sleeve and having a distal end and a proximal end, said outer sleeve and said inner sleeve being movable rotationally relative to each other;

    a screw engaging member projecting radially from the distal end of said inner sleeve and configured to engage said extension coupling surface upon relative rotation of said inner sleeve and said outer sleeve;

    a securement member including a securement surface defined adjacent the distal end of said inner sleeve and a cooperative securement surface defined adjacent the distal end of said outer sleeve, said securement surface and said cooperative securement surface being operable upon relative rotation of said inner sleeve and said outer sleeve to cooperatively engage and thereby radially secure said inner sleeve and said outer sleeve together and to maintain the engagement of said screw engaging member and said bone screw; and

    a second holding surface extending lengthwise on the distal end of said outer sleeve aligned with and engaging said first holding surface for holding said yoke and said outer sleeve together in common against rotation while said inner sleeve rotates relative to said outer sleeve and said yoke.

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