Patent ID: 7780706

Claim:
A bone anchor assembly, comprising: a fixation element adapted to engage a bone, the fixation element having a shank portion and a head portion, the shank portion having an external thread form to engage bone, and the head portion adapted to articulate relative to a coupling element; an elongate axle; a coupling element having: (a) an internal bore extending along a longitudinal axis of the coupling element, the bore sized to mate with and articulate with the head portion of the fixation element, and (b) sidewalls comprising: (i) opposing upright projections forming a first channel having a first plane and adapted to receive a connecting rod, at least a portion of the opposing upright projections having locking features on an internal surface; and (ii) opposing downward projections each comprising an aperture, wherein the apertures are opposed and form a cannulation configured to receive the axle, and wherein the opposing downward projections form a second channel defining a second plane and adapted to receive the head of the fixation element therebetween, wherein the second plane is an articulation plane other than and not parallel to the first plane along which the long axis of the connecting rod courses; wherein the axle extends through the cannulation to retain the head portion of the fixation element in the second channel and permit articulation of the fixation element between the opposing downward projections of the coupling element along the second plane and prevents articulation of the fixation element along the first plane; and a compression element engagable with the locking features of the opposing upright projections, the compression element adapted to move distally within the coupling element to transmit a compression force on a connecting rod positioned through the first channel toward the head portion of the fixation element.