A pivotal bone anchor assembly includes a shank having an anchor portion and a head with a partially spherical outer surface, a drive socket, an annular planar top surface surrounding the drive socket, and a frusto-conical surface between the planar top surface and the partially spherical outer surface. The assembly further includes a receiver having a base defining an axial bore and an upper portion defining a channel configured to receive a rod, and an insert positionable within the axial bore having an upper surface engageable with the rod, a lower surface for transferring a downwardly-directed force toward the head, and a central aperture for accessing the drive socket, with the rod extending across the central aperture when the fixation rod is engaged by the upper surface. After the head, the insert, and the rod are positioned in the receiver, the frusto-conical surface remains spaced apart from the rod to provide for increased articulation of the shank relative to the receiver.

A dynamic stabilization assembly includes a core, typically in the form of a tensioned cord, at least one pair of bone anchors, a spacer surrounding the core located between the bone anchors, at least one elastic bumper and at least one fixing or blocking member. The core is slidable with respect to at least one of the bone anchors, the spacer and the bumper. The bumper is compressed. Bone screws of the assembly include closure structures that lock against the bone screw independent of any fixing or sliding of the core with respect to the bone screw.

A system for flexibly stabilizing a vertebral motion segment of the facet joint by connecting a first vertebra and a second vertebra is disclosed. The system includes an elongate connection element with end portions interconnected by a flexible coupling member. The system includes first and second attachment portions for connecting the connection element to the vertebrae. A first resilient member is positioned between the first end portion and the first attachment portion, and a second resilient member is positioned between the first attachment portion and the second attachment portion.

A pivotal bone anchor assembly includes a receiver defining a cavity with an upper expansion region and a lower locking region, and a shank having a partial spherical head that is up-loadable into the cavity through a bottom opening. The assembly also includes a resiliently expandable retainer that is positionable within the upper expansion region with a discontinuous partial spherical internal surface and an inwardly facing surface above the discontinuous partial spherical internal surface, and a compression insert having a lower outwardly facing surface configured for side-to-side engagement with the inwardly facing surface and a downwardly facing partial spherical surface for frictionally engaging the head of the shank. The compression insert is positionable in overlapping engagement with the retainer within the receiver with the discontinuous partial spherical internal surface extending above and below a hemisphere of the head of the shank to capture the head within the retainer.

A pivotal bone anchor assembly includes a receiver having a cavity for receiving the head of a shank, a first channel for receiving an elongate rod, and an axial bore extending upward from a bottom opening of the receiver to a discontinuous thread adjacent a top of the receiver with opposed alignment members protruding inwardly beneath the discontinuous thread. The assembly also includes a pressure insert having a second channel for receiving the underside of the elongate rod, a lower surface for applying downward pressure on the shank head, and an outer cylindrical surface with opposite elongate recesses. The pressure insert is loaded into a first position within the axial bore and then rotated into a second position in which the opposed alignment members become positioned within the opposite elongate recesses to hold the second channel of the pressure insert in alignment with the first channel of the receiver.

A pivotal spinal fixation system includes bone anchors comprising capture portions having a partial spherical shape with flat side surfaces, multi-planar receivers with continuous interior circumferential engagement surfaces proximate their bottom openings, and uni-planar receivers with non-continuous interior circumferential engagement surface proximate their bottom openings. The system also includes circular retainers, each having a non-continuous outer circumferential surface configured for non-pivotal engagement with the interior circumferential engagement surfaces of both the multi-planar receivers and the uni-planar receivers, and an inner surface configured to expand and contract around the capture portion and flat side surfaces of a bone anchor so as to capture the bone anchor within a multi-planar or uni-planar receiver. The system provides for pivotal motion of the bone anchors in any of a plurality of angular directions relative to the vertical centerline axes of the multi-planar receivers while limiting pivotal motion to a single pivot plane relative to the vertical centerline axes of the uni-planar receivers.

A pivotal bone anchor assembly includes a shank having a shank head with a partial spherical shape at a proximal end and an anchor portion opposite the shank head for fixation to the bone of a patient. The assembly also includes a receiver having an upper portion defining a channel for receiving an elongate rod and a base defining a cavity in communication with the channel and with a bottom surface of the receiver through a distal opening. The assembly further includes a retainer positionable into non-rotatable and non-pivotal engagement with an inner surface of the cavity prior to the shank head being received within the cavity, with the retainer having a central opening configured to receive and capture the shank head within the cavity while allowing for pivotal motion between the shank and the receiver in at least one plane, and with a lower portion of the retainer extending below the bottom surface of the receiver.

A device for spinal correction includes a stabilizer assembly including a hinge including a first rod-bearing leaf; a second rod-bearing leaf rotatably coupled to the first rod-bearing leaf to provide coronal or sagittal freedom of movement, or both, of the stabilizer assembly; a locking mechanism to lock the first and second rod-bearing leaves at a desired angle; a first stabilizing rod coupled to the first rod-bearing leaf; a second stabilizing rod coupled to the second rod-bearing leaf; and a plurality of monoaxial or polyaxial links, wherein each monoaxial or polyaxial link is movably coupled to the first or second stabilizing rod and is movably couplable to a first spinal rod or a second spinal rod fixed to the spine; wherein the stabilizer assembly is couplable to the first or second spinal rod to stabilize the spine to prevent compression, distraction, or translation of the spinal cord during a spinal correction.

A pivotal bone anchor assembly includes a shank with a head, an anchor portion, and a neck extending between the head and the anchor portion, and a receiver with upright arms defining a channel for receiving a rod and a central bore extending downward to a lower portion of the receiver. The assembly also includes a retaining structure rotatably coupled with the receiver with an internal seating structure pivotally supporting the head while providing for independent rotation of the shank prior to locking the assembly with the rod and a closure. The retaining structure includes an external surface and a slot extending between the seating structure and the external surface with a concave cut-out configured to closely receive the neck so as to provide for increased articulation between the shank and the receiver along the slot, and with the shank and the retaining structure being rotatable together around a centerline axis to align the increased articulation in any radial direction around the circumference of the receiver.

A coupling device for coupling a rod to a bone anchor includes a receiving part configured to receive a head of the bone anchor, the receiving part having a first end and a second end, a central axis that extends between the first and second ends, and two legs at the first end that define a recess extending in a longitudinal direction transverse to the central axis for receiving the rod, and a monolithic pressure member positionable in the receiving part, the pressure member including a rod support surface and an engagement portion to adjust the pressure member to exert pressure on the head. The engagement portion is positioned farther radially from the central axis in the longitudinal direction than a first portion of the rod support surface, and extends closer axially to the first end of the receiving part than the entire first portion of the rod support surface.