Devices and methods for monoaxial screw conversion

摘要

Devices and methods for selectively converting polyaxial bone screws into monoaxial screws are described herein. In one embodiment, a spinal screw extension instrument is provided having an outer component configured to engage a receiving member of a polyaxial screw. The instrument further includes an inner component disposed within an inner lumen of the outer component and configured to translate longitudinally relative to the outer component such that the inner component can apply a distal force to a compression member of the polyaxial screw disposed within a distal portion of the receiving member to thereby convert the polyaxial screw to a monoaxial screw.

主权项

1. A spinal screw extension instrument, comprising:
an outer component having an inner lumen extending therethrough and a distal end with opposed arms configured to engage a receiving member of a polyaxial screw such that opposed slots formed between the opposed arms overlap with opposed slots formed in the receiving member; and an inner component disposed within the inner lumen of the outer component and having a distal end with opposed arms and opposed slots formed between the opposed arms, the inner component being configured to translate longitudinally relative to the outer component such that the opposed arms of the inner component overlap with the opposed arms of the outer component and the opposed slots of the inner component overlap with the opposed slots of the outer component and the receiving member, the opposed arms of the inner component being configured to apply a distal force to a compression member of the polyaxial screw disposed within a distal portion of the receiving member to thereby convert the polyaxial screw to a monoaxial screw; wherein the outer component comprises an outer sleeve configured to engage a feature formed on an outer surface of the receiving member of the polyaxial screw and an inner sleeve disposed within the outer sleeve and configured to abut against an upper surface of the receiving member of the polyaxial screw.