8. A bone stabilization assembly comprising: a bone anchor having a longitudinal anchor axis; a housing fixed to one end of the bone anchor; the housing having an exterior surface coaxial with the anchor axis; the housing having an internal bore coaxial with anchor axis; a post extending from the bore the post being secured to the bone anchor in a manner that allows deflection of the post relative to bone anchor in response to a load; a clamp ring mounted on the exterior surface of the housing wherein the clamp ring may be positioned at a plurality of positions around the anchor axis relative to the housing; a rod clamp having a channel sized and adapted to receive a spinal rod along a channel axis; a rotary joint connecting the clamp ring and the rod clamp which allows the rod clamp to rotate relative to the clamp ring around a joint axis which is perpendicular to the anchor axis; a fastening mechanism including a single fastener, wherein operation of the single fastener is adapted to secure a spinal rod within the channel, lock the rotary joint and secure the clamp ring to the housing and the housing has a plurality of splines extending at intervals from the exterior surface and oriented parallel to the longitudinal axis of the bone screw; the clamp ring has a plurality of complementary splines; whereby the clamp ring may be secured in a plurality of discrete angular orientations about the housing and whereby the splines of the housing can engage the splines of the clamp ring to prevent rotation of the clamp ring when the clamp ring is secured to the housing.
9. The bone stabilization assembly of claim 8 , wherein the channel axis intersects the anchor axis.