Multi-thread bone screw and method

摘要

A bone screw comprises a threaded shank including a distal end portion and a proximal end portion, and defining a first threaded section extending from the distal end portion toward the proximal end portion and adapted for anchoring in cancellous bone. A second threaded section extends contiguously from the first threaded section toward the proximal end portion The second threaded section has a finer thread pattern relative to the first threaded section. In one embodiment, the first threaded section includes a first helical threading defining a single lead thread pattern for anchoring in cancellous bone, and the second threaded section includes a second helical threading interleaved with the first threading to define a duel lead thread pattern for engagement in cortical bone. In a further embodiment, the bone screw includes a head portion extending from the threaded shank and configured for coupling to a spinal implant.

主权项

1. A bone screw configured to enter into tissue having a first hardness and a second hardness, the bone screw comprising:
a threaded shank extending along a longitudinal axis between a distal end portion and a proximal end portion, said threaded shank defining a first threaded section extending from said distal end portion toward said proximal end portion, said threaded shank defining a second threaded section extending contiguously from said first threaded section toward said proximal end portion, said second threaded section comprising a finer thread pattern relative to said first threaded section, wherein said threaded shank includes a first helical threading having a single thread type extending along said threaded shank from said first threaded section and into said second threaded section, said threaded shank including a second helical threading interleaved with said first helical threading to define said second threaded section, each of said first and second helical threadings having a substantially equal thread pitch, a head portion extending from said proximal end portion of said threaded shank, said bone screw being coaxial with said longitudinal axis from said proximal end portion to said head portion, said head portion being configured to have a spinal implant coupled thereto, wherein said head portion comprises a pair of spaced apart arms defining a U-shaped channel therebetween and said spinal implant comprises a spinal rod that is configured to be captured within the U-shaped channel, and a set screw having a threaded outer surface, wherein inner surfaces of said arms are threaded and are configured to engage the threaded outer surface to couple said set screw to said head portion, wherein said bone screw is configured for insertion into an inner region of said tissue having said first hardness and an outer region of said tissue having said second hardness, said second hardness being greater than said first hardness, said bone screw being configured for insertion into said tissue such that said first threaded section penetrates said inner region after said first threaded section penetrates said outer region.