1. A spinal rod adapted to stabilize the spine, wherein the spinal rod comprises: an elongated rod having a first end, a second end and a longitudinal rod axis; a housing at the first end of the of the rod; a rod bore passing through the housing perpendicular to the rod axis; a spherical pocket within the bore; a ball-shaped mount trapped within the spherical pocket; a ball bore passing through the ball-shaped mount and adapted to receive a post; and the ball-shaped mount being dimensionally stable such that when the ball-shaped mount is secured to a post, the ball-shaped mount can still pivot and rotate within the spherical pocket of the elongated rod thereby enabling the elongated rod to be secured to the post while allowing the elongated rod to pivot and rotate relative to the post.
1. A spinal rod adapted to stabilize the spine, wherein the spinal rod comprises: an elongated rod having a first end, a second end and a longitudinal rod axis; a housing at the first end of the of the rod; a rod bore passing through the housing perpendicular to the rod axis; a spherical pocket within the bore; a ball-shaped mount trapped within the spherical pocket; a ball bore passing through the ball-shaped mount and adapted to receive a post; and the ball-shaped mount being dimensionally stable such that when the ball-shaped mount is secured to a post, the ball-shaped mount can still pivot and rotate within the spherical pocket of the elongated rod thereby enabling the elongated rod to be secured to the post while allowing the elongated rod to pivot and rotate relative to the post. 7. The spinal rod of claim 1 , in combination with a bone screw, wherein: the bone screw comprises a threaded shaft adapted to engage a vertebra and a post that can mount the ball-shaped mount; and the bone screw is configured such that the post may deflect relative to the threaded shaft in response to a load placed on the post by the spinal rod.