Pedicle screw with expansion anchor sleeve

{
  "publication_number": "US2010324607A1",
  "country": "US",
  "kind": "A1",
  "title": "Pedicle screw with expansion anchor sleeve",
  "abstract": "A bone anchor for use in conjunction with orthopedic spinal fixation comprising a pedicle screw having a threaded proximal tip for threaded insertion into a hole prepared into a vertebral body through the pedicle of the vertebra from the posterior approach. The shank of the anchor is of smaller diameter than the proximal tip so as to receive a sleeve after insertion into the bone. The tubular sleeve is provided with a plurality of longitudinal slots evenly arranged about the longitudinal axis of the sleeve to forming a plurality of longitudinal. A tubular compression collar for insertion over said shank portion is provided on the shank and driven toward the proximal tip compression the sleeve and causing the ribs to expand radially into a star pattern securing the anchor in the bone. A tubular collar of natural or synthetic bone growth promoting material may be inserted to promote bone growth, close the hole and further stabilize the anchor. An elastomeric collar may also be inserted over the shank and extend beyond the end of the shank to flexibly receive a rod seat for receiving an orthopedic rod affixed to said elastomeric collar.",
  "claims": [
    "1. A bone anchor comprising a screw having a shank portion and proximal portion, the proximal portion having a diameter greater than the shank portion, said proximal portion characterized by external threads for engagement with a hole prepared in a bone; a tubular sleeve having a first end and a second end and sized for insertion over said shank portion of the said screw wherein said first end is engaged with said proximal portion, said sleeve having a plurality of longitudinal slots arranged about the longitudinal axis of said sleeve thereby forming a plurality of longitudinal ribs there between; a tubular collar for insertion over said shank portion wherein said collar is engaged with said second end of said sleeve. 2. The bone anchor of claim 1 further comprising a tubular collar of natural or synthetic bone growth promoting material for insertion over said shank portion wherein said bone growth promoting material collar is advanced down said shank so as to contact said bone; an elastomeric collar for insertion over said shank portion, said elastomeric extending beyond the distal end of said shank portion; and a rod seat for receiving an orthopedic rod affixed to said elastomeric collar. 3. A method of securing a bone anchor to a bone comprising the steps of: providing a pre-drilled hole in a bone; inserting into said hole a bone screw having a shank portion and proximal portion, the proximal portion having a diameter greater than the shank portion, said proximal portion characterized by external threads, said thread engaging the surface of said bone within said hole so as to advance said proximal portion of said screw into said hole on rotation of said shank portion; inserting a tubular sleeve having a first end and a second end over said shank portion of the said screw and into said hole wherein said first end is engaged with said proximal portion of said bone screw, said sleeve having a plurality of longitudinal slots arranged about the longitudinal axis of said sleeve thereby forming a plurality of longitudinal ribs there between; inserting a compression collar over said shank portion of the said screw and into said hole wherein said compression collar is engaged with said second end of said sleeve; driving said compression collar down said shank toward said proximal end thereby compressing said sleeve and causing said ribs form a radial pattern of arms substantially perpendicular to said longitudinal axis, said pattern having a diameter greater than the diameter of said hole. 4. The method of claim 3 further comprising inserting over said shank portion a collar of natural or synthetic bone growth promoting material, said bone growth promoting material collar being advanced down said shank so as to contact said bone. 5. The method of claim 3 further comprising inserting over said shank portion an elastomeric collar, said elastomeric extending beyond the distal end of said shank portion. 6. The method of claim 5 further comprising inserting a rod seat on to said elastomeric collar for receiving an orthopedic rod."
  ],
  "description_excerpt": "1. Field of the Invention\n\nThe present invention relates to spinal fixation devices and, more particularly to a modular screw/sleeve assembly for insertion into spinal bone for fixation of the vertebra such as by affixing orthopedic implantation structures to the spine.\n\n2. Description of the Background\n\nThe spinal column is a highly complex arrangement of 24 individual vertebral bones separated by cartilaginous intervertebral discs supported by muscle and ligament that houses and protects critical elements of the nervous system and supports the body. Despite this role the spine is a highly flexible structure that is capable of significant articulation through a wide range of motion. In a healthy spine this flexibility is a result of its composite nature which permits relative movement between adjacent vertebra at the intervertebral discs and at the facet joints. The spinal vertebra vary in form along the length of the spine but are generally comprised of a roughly cylindrical vertebral body anterior to a central canal that houses the spinal cord. The central canal is formed and the spinal cord protected from the posterior approach by the vertebral arch, which is itself comprised of two pedicles extending laterally from the vertebral body and joined medially by the lamina. The transverse process extend laterally from the pedicle/laminar joint and the spinous process extends posteriorily and generally down from medial line where the plates of the lamina join. The cylindrical vertebral bodies are stacked and separated from each other by resilient intervertebral discs.",
  "cpc": [
    "A61B 17/8685",
    "A61B 17/7032",
    "A61B 17/8625",
    "A61B 17/864"
  ],
  "ipc": [
    "A61B 17/86"
  ],
  "inventors": [
    "Reginald J. Davis"
  ],
  "filing_date": "2010-06-23",
  "publication_date": "2010-12-23",
  "priority_date": "2009-06-23",
  "application_number": "US-82194510-A",
  "family_id": "43354961",
  "cited_by_count": 183,
  "citations": [
    "US4379451A",
    "US5634926A",
    "US20040199165A1"
  ]
}