An improved dynamic longitudinal connecting member includes a rod portion joined with a tensioned cord portion, for use in a medical implant assembly having at least two bone attachment structures, a spacer covering the join of the rod and cord portions and extending between the at least two bone attachment structures, a sleeve, a bumper and a cord blocker. The spacer and bumper are compressed. The cord portion is slidable with respect to at least one of the bone attachment members.

A vertebral fixing system having a flexible elongated member, a connecting part, and an anchor, where the anchor may engage a bone structure (e.g., a vertebra) through an opening of the connecting part and the flexible elongated member may connect to the connecting part. In some cases, the vertebral fixing system may include a tightening part configured to apply a tension to the elongated member and/or secure the elongated member with respect to the connecting part. The vertebral fixing system may be configured to receive a rod and may be capable of connecting thereto. The connecting part may have a plurality of connecting members, where at least one of the connecting members includes an opening for receiving the anchor and at least one of the connecting members connects to the elongated member.

A pivotal bone anchor assembly includes a receiver having a central bore with a seating surface adjacent a bottom opening and a downward-facing surface above the seating surface, and a shank having a head portion positionable within the axial bore. The assembly also includes a compression insert positionable within the central bore above the head portion and having an upper portion with a notch formed therein to define a resiliently compressible structure extending over the notch. When the head portion of the shank and the compression insert are positioned together in the central bore of the receiver, the engagement between the resiliently compressible structure and the downward-facing surface is configured to provide an axially directed resilient biasing force for a pre-lock friction fit of the pivotal bone anchor assembly prior to securing the longitudinal connecting member in the open channel with the closure.

A vertebral fixing system having a flexible elongated member, a connecting part, and an anchor, where the anchor may engage a bone structure (e.g., a vertebra) through an opening of the connecting part and the flexible elongated member may connect to the connecting part. In some cases, the vertebral fixing system may include a tightening part configured to apply a tension to the elongated member and/or secure the elongated member with respect to the connecting part. The vertebral fixing system may be configured to receive a rod and may be capable of connecting thereto. The connecting part may have a plurality of connecting members, where at least one of the connecting members includes an opening for receiving the anchor and at least one of the connecting members connects to the elongated member.

An improved dynamic longitudinal connecting member includes a rod portion joined with a tensioned cord portion, for use in a medical implant assembly having at least two bone attachment structures, a spacer covering the join of the rod and cord portions and extending between the at least two bone attachment structures, a sleeve, a bumper and a cord blocker. The spacer and bumper are compressed. The cord portion is slidable with respect to at least one of the bone attachment members.

A functionally dynamic stabilization unit and system for treatment of spinal instability are provided. Each unit, and collectively, the system, is configured to control flexion, extension and translation of the affected unstable vertebral area, thereby stabilizing the vertebral segments by restoring normal function. This is achieved by providing a unit and system that allow for lateral bending, axial compression, rotation, anterior segmental height adjustment, and posterior segmental height adjustment. The unit and system provide sufficient segmental stiffness, while also limiting, or controlling, the range of motion (i.e., sufficient stiffness in the neutral or active zone, while limiting or preventing motion outside of the active zone) to stabilize the vertebral segments. In use, the system mimics the natural movement of the normal spine. Furthermore, the system includes a rigid, fusion-promoting coupler configured for use in an adjacent level, or as a substitute for the functionally dynamic unit. The modularity of the system allows adjustment over time and easier revision surgery, and is configured for minimally-invasive, delivery or implantation.

A receiver assembly for capturing an elongate rod in a receiver of a bone anchor includes the receiver, a first threaded closure, and a second threaded closure. The receiver includes an upper portion that defines a first channel, interior surfaces that have helically wound thread, and a lower pressure insert that can be positioned within the first channel and has upright arms. Each of the first threaded closure and the second threaded closure have a cylindrical body with an external surface having continuous helically wound thread that can rotatably mate with the helically wound receiver thread. The first threaded closure and the second threaded closure are interchangeable for different locking configurations in the receiver assembly. The first threaded closure has a downward protrusion that can compressively engage the elongate rod. The second threaded closure has a bottom surface that can compressively engage the upright arms of the lower pressure insert.

A pivotal bone anchor assembly includes a shank having a shank head and an anchor portion, and a receiver having a first channel for receiving a rod and an axial bore for receiving the shank head, with the axial bore including a downwardly-facing abutment surface and opposed rotation blocking and alignment structures beneath a helically wound thread. The assembly also includes a pressure insert having a second channel and opposite outwardly-projecting flanges with notches formed therein. The pressure insert is top loaded into a first position within the axial bore with the second channel in a mal-aligned position relative to the first channel, with subsequent rotation of the pressure insert moving the second channel into alignment with the first channel, the opposite outwardly-projecting flanges under the downwardly-facing abutment surface, and the opposed rotation blocking and alignment structures into the notches formed into the opposite outwardly-projecting flanges.

A medical implant assembly includes a polyaxial bone anchor having a shank, a receiver, a lower compression insert with planar surfaces for closely receiving an elongate connecting member with planar surfaces and a one-piece closure structure. The connecting member is made from a polymer. The closure structure engages both the connecting member and the insert with the engagement between the closure structure and the insert securely locking the polyaxial mechanism even if the connecting member exhibits creep.

Fixation systems including a member, a first attachment portion, a second attachment portion, and an intermediate portion. The first attachment portion is attached at a superior end of the member and includes a first opening. The second attachment portion is attached at an inferior end of the member and includes a second opening. The intermediate portion connects the first and second attachment portions. The fixation systems may also include a relief in at least one of the first opening and the second opening. Surgical methods for inserting the fixation systems in a patient are also disclosed.