Bone Anchor Assemblies and Methods With Improved Locking

摘要

Various exemplary methods and devices are provided for fixing bone anchors to bone. In general, the methods and devices can allow for a bone anchor to be fixed to a bone at a desired angle to a receiver member. In an exemplary embodiment, a bone anchor assembly is provided that includes a bone anchor configured to engage bone, a receiver member that seats a spherical head of the bone anchor and a spinal fixation element, a compression member seated within the receiver member, proximally of the head of the bone anchor, and a closure mechanism seated within the receiver member, proximally of the compression member. One or more of the receiver member, the compression member, and the closure mechanism can have gripping features thereon configured to secure the bone anchor and/or the spinal fixation element within the receiver member, thereby reducing a risk of slippage of the bone anchor and/or the spinal fixation element with respect to the receiver member.

主权项

1. A bone anchor assembly, comprising:
a bone anchor having a proximal head portion and a distal shank portion; a receiver member having a polyaxial seat formed therein for polyaxially seating the head portion of the bone anchor; a closure mechanism matable with the receiver member to lock the bone anchor within the receiver member; and a compression member configured to be disposed within the receiver member between the bone anchor and the closure mechanism, the compression member having a proximal end configured to seat a distal end of the closure mechanism, the proximal end having a shape that causes the compression member to move radially inward when a distally-directed force is applied thereto by the closure mechanism that exceeds a threshold force.