Patent ID: 9433446
Filing Date: 2016-09-06
CPC Classification: A61B

Claim Text:
1. An anchor extension for releasably coupling to a spinal bone anchor comprising: an elongate hollow outer sleeve having a distal end, a proximal end, and a perimetric sidewall defining a bore through said distal and proximal ends, an interlocking engagement surface defined adjacent the distal end of said outer sleeve, and a pair of opposing slots formed through said sidewall, each slot opening through the distalmost edge of said outer sleeve and extending for a length proximally of said interlocking engagement surface; an elongate hollow inner sleeve disposed within the bore of said outer sleeve and having a distal end, a proximal end, and a perimetric sidewall defining a bore through said distal and proximal ends, a cooperative interlocking engagement surface defined adjacent the distal end of said inner sleeve, and a pair of opposing slots formed through said sidewall, each slot opening through the distalmost end of said inner sleeve and extending for a length proximally of said cooperative interlocking engagement surface, said outer sleeve and said inner sleeve being movable rotationally relative to each other such that the slots of said inner sleeve are aligned with the slots of said outer sleeve without the perimetric sidewall of the distal end of said outer sleeve extending across the slots of said inner sleeve; and an anchor engaging member projecting radially from the distal end of one of said outer sleeve and said inner sleeve for engaging the bone anchor upon relative rotation of said inner sleeve and said outer sleeve, said anchor engaging member being separate from and more distally of each of said interlocking engagement surface and said cooperative interlocking engagement surface, wherein said interlocking engagement surface and said cooperative interlocking engagement surface are operable upon relative rotation of said inner sleeve and said outer sleeve to directly interlock cooperatively with each other and thereby radially secure said inner sleeve and said outer sleeve together against radial movement for maintaining the engagement of said screw engaging member and said bone screw with said slots of said inner sleeve and said outer sleeve being in alignment.