Patent ID: 9724130
Date: 2017-08-08
CPC Classifications: A61B

Claim:
1. A bone screw assembly, comprising: a screw having a proximal head portion and a distal shank portion; a receiver member polyaxially coupled to the head portion of the screw; a compression cap disposed within the receiver member and having a distal end configured to engage the head portion of the screw, the compression cap including opposed projections extending radially therefrom configured to mate with complementary recesses formed in the receiver member, the compression cap being retained within the receiver member while still allowing polyaxial movement of the receiver member relative to the screw, wherein at least one dimension of the recesses is larger than a corresponding dimension of the projections to allow for some adjustment of the compression cap when the projections are seated in the recesses, wherein the compression cap includes first and second deformable arms having free ends configured to deflect inwards during assembly of the compression cap to the receiver member and to then deflect radially outward when the compression cap is seated in the receiver member, wherein the compression cap is positionable with respect to the receiver member in a first, distal position in which ramped outer surfaces of the arms engage a distal ramped surface of the interior of the receiver member and a second, proximal position in which the ramped outer surfaces of the arms do not engage and are proximal to the distal ramped surface of the interior of the receiver member, and wherein the ramped outer surfaces of the arms of the compression cap move towards each other as the arms are deflected inwards.