Patent ID: 8603144
Filing Date: 2013-12-10
Classification: A61B

Abstract:
1. A bone screw assembly comprising: a bone anchor having a distal shaft extending along a longitudinal axis configured to engage bone; a proximal head portion; and a rod seat disposed within the proximal head portion for seating the spinal rod, wherein the rod seat allows for a controlled pivoting movement of the spinal rod about two selected axes in two directions relative to the head portion, wherein the proximal head portion includes a U-shaped slot and a recess formed in a bottom surface of the U-shaped slot for receiving the rod seat, wherein the rod seat includes: a first lower element rotatable relative to the proximal head portion in a first direction about a first axis; and a second lower element stacked on the first lower element and rotatable relative to the first lower element in a second direction about a second axis perpendicular to the first axis.