A dynamic fixation medical implant having at least two bone anchors includes a longitudinal connecting member assembly having at least one transition portion and cooperating outer sleeve, both the transition portion and sleeve being disposed between the two bone anchors. In a first embodiment, the transition portion includes a rigid length or rod having apertures therein for tying or otherwise attaching the rigid length to a second rigid length or to a flexible cord. Slender ties or cords extend through a plurality of apertures in the rigid lengths or are threaded, tied or plaited to the larger flexible cord or cable. In a second embodiment, a transition portion includes slender ties of a cord that are imbedded in a molded plastic of a more rigid member. The outer sleeve may include compression grooves. The sleeve surrounds the transition portion and extends between the pair of bone anchors, the sleeve being compressible in a longitudinal direction between the bone anchors.

According to some embodiments, systems and methods of ultrasonic detection of implantable medical device distraction are provided. The system includes a first elongate member and a second elongate member. The first elongate member has a first end that is configured to be attached to a first location on the skeletal system of a subject, a second end, and at least one landmark identifiable using ultrasound. The second elongate member has a first end that is movably coupled to the second end of the first elongate member, a second end configured to be attached to a second location on the skeletal system, and at least one landmark identifiable using ultrasound. Movement of the first elongate member in relation to the second elongate member causes a corresponding movement of the at least one first landmark in relation to the at least one second landmark which can be detected using ultrasound.

A method for securing a longitudinal connection member assembly into multiple bone anchors by inserting the assembly into the bone anchors before or after the assembly is tensioned. The assembly includes a tensionable cord, an outer end blocker, and a set screw. The cord has a first end portion fixedly connected to a first structure, extends through a through-bore of a second structure, and has a second end portion that extends through a blocker through-bore of the outer end blocker. The outer end blocker has oppositely spaced lateral external planar surfaces and a threaded closed bore. The set screw is releasably engageable to the outer end blocker via the threaded closed bore. The method further includes tensioning the cord from the second end portion, holding the planar surfaces during tensioning of the cord within the blocker, and securing the tensioned cord to the outer end blocker by the set screw.

A dynamic longitudinal connecting member assembly includes an anchor member having an integral or otherwise fixed elongate core of circular or non-circular cross-section. The core is pre-tensioned and extends through at least one elastic spacer and at least one outer sleeve. The anchor member and the outer sleeve each attach to at least one bone anchor. In operation, the core is held in tension by the spacer.

A bone anchor assembly includes a receiver having a channel for receiving a rod and a central bore with a locking recess adjacent a bottom opening, an expansion recess above the locking recess, and a discontinuous retaining groove above the expansion recess. The assembly also includes a bone screw having a capture portion uploadable into the central bore through the bottom opening, and an insert positionable within the central bore prior to the capture portion with a pair of protruding engagement structures received within the discontinuous retaining groove. The assembly further includes a lower open ring configured for expansion within the expansion recess prior to downward movement into the locking recess to capture and hold the capture portion within receiver, and an upper open ring positionable within the central bore between the lower open ring and the insert. After the capture portion of the bone screw is captured by the lower open ring, the insert is downwardly deployable by tooling to move the insert into engagement with the capture portion with the pair of engagement structures moving downwardly into engagement with a discontinuous lower overlying surface formed into the central bore, and the upper open ring is configured to occupy the upper expansion recess.

A pivotal bone anchor assembly includes a receiver having a central bore with an integral downward facing surface below a helically wound guide and advancement structure and a first interference surface, and a compression insert configured for top-loading into the central bore into a first position and then being rotatable about the receiver longitudinal axis into a second position defined by an engagement between a second protuberant interference surface of the compression insert and a first interference surface of the central bore. The compression insert further includes radially offset upwardly facing surfaces configured for biased engagement with a downward facing surface of the central bore upon completion of rotation to the second position, and the receiver further includes one or more inwardly extending integral non-resilient structure positionable into one or more outer alignment grooves of the compression insert, also upon the completion of rotation to the second position.

A dynamic longitudinal connecting member assembly includes an anchor member having an integral or otherwise fixed elongate core of circular or non-circular cross-section. The core is pre-tensioned and extends through at least one elastic spacer and at least one outer sleeve. The anchor member and the outer sleeve each attach to at least one bone anchor. In operation, the core is held in tension by the spacer.

A receiver subassembly adapted to couple with the capture portion of a bone anchor or shank to form a pivotal bone anchor assembly. The receiver subassembly includes a receiver having cavity above a distal opening sized and shaped for bottom loading the capture portion there-through, with the cavity configured to support both a split ring retainer and second split ring above of the spit ring retainer within the receiver. The receiver subassembly further includes an insert positionable in the receiver above the split rings and configured for downward deployment by tooling to engage the capture portion of the bone anchor. The split ring retainer is configured to expand around and close below the capture portion of the bone anchor upon an uploading of the capture portion into the cavity, so as to capture the capture portion within the cavity with the bone anchor extending downward through the distal opening.

A dynamic fixation medical implant having at least two bone anchors includes a longitudinal connecting member assembly having at least one transition portion and cooperating outer sleeve, both the transition portion and sleeve being disposed between the two bone anchors. In a first embodiment, the transition portion includes a rigid length or rod having apertures therein for tying or otherwise attaching the rigid length to a second rigid length or to a flexible cord. Slender ties or cords extend through a plurality of apertures in the rigid lengths or are threaded, tied or plaited to the larger flexible cord or cable. In a second embodiment, a transition portion includes slender ties of a cord that are imbedded in a molded plastic of a more rigid member. The outer sleeve may include compression grooves. The sleeve surrounds the transition portion and extends between the pair of bone anchors, the sleeve being compressible in a longitudinal direction between the bone anchors.

A pivotal bone anchor assembly includes a receiver having upright arms defining a receiver channel for receiving an elongate rod, and an axial bore extending downward from the receiver channel to a bottom opening. The upright arms include break-off extensions, outer horizontally extending curvate tool engagement grooves, and side apertures extending inwardly from outer surfaces of the upright arms to deformable crimp wall portions adjacent the axial bore. The assembly also includes a shank having an anchor portion and an integral upper portion that is positionable in the axial bore of the receiver with the shank extending downward through the bottom opening. The assembly further includes an insert with an insert channel positionable within the axial bore and having opposing depressions formed into side surfaces that are configured to cooperate with the crimp wall portions of the receiver to maintain the insert channel in alignment with the receiver channel.