Implants and instruments for enhancing vertebral alignment and sagittal balance

1. A pivoting screw assembly for surgical implantation, comprising:

a fixation screw, including:

a threaded shank, and a head having a concave curved cradle that is shaped and disposed to receive, contact, and support a cylindrical stabilization rod, and a tapered surface that is adjacent to the threaded shank, the tapered surface including a linear taper, a curved taper, or a combination thereof, wherein the screw head further includes a plurality of contoured surfaces sloping away from the cradle toward the tapered surface, the plurality of contoured surfaces adapted to support the cylindrical stabilization rod and including contours selected from the group consisting of bevels, chamfers, curves, and combinations thereof;

a receiver body adapted for engagement with the fixation screw having an aperture

having a generally U-shaped conformation, and including

a base that includes a curved exterior surface, an interior surface having a through slot for receiving the shank and a seat with a curved surface for contacting the tapered surface of the fixation screw; and

opposing sidewalls extending from the base, the opposing sidewalls including interior and exterior surfaces, and including on the interior surfaces opposing flats adjacent to the base and a threaded portion proximal to the flats; and

wherein the base and the opposing sidewalls are shaped and disposed to receive the spinal stabilization rod in contact with the cradle of the screw head inserted in the through slot, and

wherein the curved exterior surface of the base and the curved surface of the seat of the base include an essentially common curvature.

2. The pivoting screw assembly of claim 1 , further comprising a generally cylindrical compression component including a threaded surface disposed and arranged to engage with the threaded portions on the interior surfaces of the opposing sidewalls of the receiver body, the compression component shaped to contact and compress against a spinal stabilization rod in contact with the cradle of the screw head.

3. The pivoting screw assembly of claim 1 , further comprising:

a spinal stabilization rod including

a shaft including a first terminus and a second terminus;

a head disposed at the first terminus, the head including a curved contact surface; and

an engagement recess disposed in the curved contact surface.

4. The pivoting screw assembly of claim 1 , wherein the receiver body includes a pair of opposing slats extending from above the threaded portion away from the seat, the pair of opposing slats defining a central passage and a handle grip adapted to be affixed to the elongate slats via insertion of the slats into opposing engagement slots, the handle grip including a central through hole, wherein the opposing slats are removably attached to the receiver body.

5. The pivoting screw assembly of claim 4 , wherein the central passage has a circumference that is defined by the pair of opposing slats, and wherein not more than 60% of the circumference includes combined circumferential edges of the pair of opposing slats, and at least 40% of the circumference is defined by gaps between the opposing slats.

6. The pivoting screw assembly of claim 4 , wherein the pair of opposing slats is detachable from the receiver body opposing sidewalls and includes a score for removal from the receiving body.

7. The pivoting screw assembly of claim 1 , further including a footing, the footing including a curved support surface shaped and disposed to support the curved exterior surface of the base, the curved support surface of the footing including the essentially common curvature.

8. The pivoting screw assembly of claim 1 , wherein the plurality of contoured surfaces are adapted to support the cylindrical stabilization rod that is inserted through the generally U-shaped conformation of the receiver body where an angulation of the rod precludes the rod from resting on the cradle.

9. A pivoting screw assembly for surgical implantation, comprising:

a fixation screw, including:

a threaded shank, and a head having a concave curved cradle that is shaped and disposed to receive and support a cylindrical stabilization rod, and a tapered surface that is adjacent to the threaded shank, the tapered surface including a linear taper, a curved taper, or a combination thereof, wherein the screw head further includes a plurality of contoured surfaces sloping away from the cradle toward the tapered surface, the plurality of contoured surfaces adapted to support the cylindrical stabilization rod and including contours selected from the group consisting of bevels, chamfers, curves, and combinations thereof;

a receiver body adapted for engagement with the fixation screw having an aperture having a generally U-shaped conformation, and including

a base that includes a curved exterior surface, an interior surface having a through slot for receiving the shank and a seat with a curved surface for contacting the tapered surface of the fixation screw; and

opposing sidewalls extending from the base, the opposing sidewalls including interior and exterior surfaces, and including on the interior surfaces opposing flats adjacent to the base and a threaded portion proximal to the flats; and

wherein the base and the opposing sidewalls are shaped and disposed to receive the spinal stabilization rod in contact with the cradle of the screw head inserted in the through slot,

wherein the curved exterior surface of the base and the curved surface of the seat of the base include an essentially common curvature, and

wherein, as assembled, the curved exterior surface of the base, and the curved surface of the seat of the base, restrict rotation of the receiver body to a single axis of rotation aligned with the essentially common curvature and wherein the opposing flats limit the extent of pivotal movement of the receiver body.

10. A pivoting screw assembly for surgical implantation, comprising:

a fixation screw, including:

a threaded shank, and a head having a concave curved cradle that is shaped and disposed to receive and support a cylindrical stabilization rod, and a tapered surface that is adjacent to the threaded shank, the tapered surface including a linear taper, a curved taper, or a combination thereof;

a receiver body adapted for engagement with the fixation screw having an aperture having a generally U-shaped conformation, and including

a base that includes a curved exterior surface, an interior surface having a through slot for receiving the shank and a seat with a curved surface for contacting the tapered surface of the fixation screw; and

opposing sidewalls extending from the base, the opposing sidewalls including interior and exterior surfaces, and including on the interior surfaces opposing flats adjacent to the base and a threaded portion proximal to the flats; and

a footing, the footing including a curved support surface shaped and disposed to support the curved exterior surface of the base, the curved support surface of the footing including the essentially common curvature;

wherein the base and the opposing sidewalls are shaped and disposed to receive the spinal stabilization rod in contact with the cradle of the screw head inserted in the through slot,

wherein the curved exterior surface of the base and the curved surface of the seat of the base include an essentially common curvature, and

wherein the footing includes at least one clocking alignment recess, and the fixation screw includes at least one clocking alignment projection arranged and disposed to interlock with the at least one clocking alignment recess when assembled.

11. The pivoting screw assembly of claim 10 , wherein the screw head further includes a plurality of contoured surfaces sloping away from the cradle toward the tapered surface, the plurality of contoured surfaces including contours selected from the group consisting of bevels, chamfers, curves, and combinations thereof.