Patent ID: 8182512
Filing Date: 2012-05-22
Classification: A61B,A61F

Abstract:
1. A facet joint prosthesis comprising: a first pedicle screw, a second pedicle screw and a third pedicle screw, wherein the first pedicle screw, second pedicle screw and third pedicle screw each comprise a threaded shaft and a screw head; first outer member comprising a first end and a second end, wherein the first end comprises an open ended elongate bulbous portion, the open ended elongate bulbous portion having an open end and an elongate bulbous cavity central to the elongate bulbous portion, the elongate bulbous portion tapering to a shaft via a neck portion, the shaft extending toward the second end, wherein the second end comprises an eyelet having a central passage that receives the first pedicle screw and a beveled inner rim that surrounds the central passage and supports the first pedicle screw head; and first inner member comprising a first end and a second end, wherein the first end comprises an elongate bulbous portion that tapers to a shaft via a neck portion, the shaft extending toward the second end, wherein the second end comprises an eyelet having a central passage that receives the second pedicle screw and a beveled inner rim that surrounds the central passage and supports the second pedicle screw head; a second outer member comprising a first end and a second end, wherein the first end comprises an open ended elongate bulbous portion, the open ended elongate bulbous portion having an open end and an elongate bulbous cavity central to the elongate bulbous portion, the elongate bulbous portion tapering to a shaft via a neck portion, the shaft extending toward the second end, wherein the second end comprises an offset eyelet having a central passage that receives the third pedicle screw, the offset eyelet being either stepped up or stepped down from the shaft to which the offset eyelet is attached; and a second inner member comprising a first end and a second end, wherein the first end comprises an elongate bulbous portion that tapers to a shaft via a neck portion, the shaft extending toward the second end, wherein the second end comprises an offset eyelet having a central passage that receives the third pedicle screw, the offset eyelet being either stepped up or stepped down from the shaft to which the offset eyelet is attached, wherein the elongate bulbous cavity of the first outer member receives the elongate bulbous portion of the second inner member through a cavity slot in the open ended elongate bulbous portion of the first outer member, with the shaft of the second inner member extending out of the open end of the open ended elongate bulbous portion of the first outer member, wherein the elongate bulbous cavity of the second outer member receives the elongate bulbous portion of the first inner member through a cavity slot in the open ended elongate bulbous portion of the second outer member, with the shaft of the first inner member extending out of the open end of the open ended elongate bulbous portion of the second outer member, and wherein the offset eyelet of the second outer member and the offset eyelet of the second inner member are so constructed as to align with one another in a manner that the shafts of the second outer member and the second inner member will be approximately aligned in plane when the third pedicle screw is received through the two, respective, offset eyelets.