A medical device includes a first elongate member defining an interior region and configured to be coupled to a first anatomical structure within a body and a second elongate member configured to be coupled to a second anatomical structure within the body. A portion of the second elongate member is configured to be disposed within the interior region. The first and second elongate members collectively have a first configuration in which they collectively have a first length when the portion of the second elongate member is disposed within the interior region of the first elongate member. When coupled to the first and second anatomical structures, the first and second elongate members can be moved to a second configuration in which they collectively have a second length different than the first length.

Bone anchors and related systems and elements, such as means for engaging a ligament to a bone anchor for correction of spinal deformities. In some embodiments, the bone anchor may be configured for engaging vertebral bone and may comprise an exterior thread form and an interior thread form, which may be positioned within an interior chamber of the bone anchor that may open at the distal end of the bone anchor where an outer thread form may also terminate. The inner chamber may taper in an opposite direction relative to an outer surface of the bone anchor upon which the outer thread form is positioned.

Systems and methods for reducing the risk of PJK, PJF, and other conditions are disclosed herein. In some embodiments, a longitudinal extension can be added to a primary fixation construct to extend the construct to one or more additional vertebral levels. The extension can be attached to a first attachment point, such as a bone anchor implanted in a vertebra that is superior to the primary construct. The extension can also be attached to a second attachment point, such as a component of the primary construct or an anatomical structure disposed inferior to the first attachment point. The extension can be more flexible than the primary construct and/or can limit motion to a lesser degree than the primary construct, thereby providing a more-gradual transition from the instrumented vertebrae to the natural patient anatomy adjacent thereto. The extension can be placed with little or no soft tissue disruption.

Systems and methods for reducing the risk of PJK, PJF, and other conditions are disclosed herein. In some embodiments, a longitudinal extension can be added to a primary fixation construct to extend the construct to one or more additional vertebral levels. The extension can be attached to a first attachment point, such as a bone anchor implanted in a vertebra that is superior to the primary construct. The extension can also be attached to a second attachment point, such as a component of the primary construct or an anatomical structure disposed inferior to the first attachment point. The extension can be more flexible than the primary construct and/or can limit motion to a lesser degree than the primary construct, thereby providing a more-gradual transition from the instrumented vertebrae to the natural patient anatomy adjacent thereto. The extension can be placed with little or no soft tissue disruption.

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. The transition portion includes a rigid length or rod having apertures therein and a molded plastic length that extends through the apertures, thus attaching the plastic length to the rigid length. 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.

Methods for correction of spinal deformities using bone anchors having one or more features configured to actively draw in and/or compact vertebral bone into an inner chamber. In some implementations, a first bone anchor having an inner chamber may be advanced into a first vertebral body of a spinal column. One of more features of the inner chamber may, as the first bone anchor is rotatably or otherwise advanced, actively draw and compact vertebral bone into the inner chamber. A second bone anchor may be advanced into a second vertebral body of the spinal column, after which a tether may be coupled between the first and second bone anchors to apply a corrective force to at least a portion of the spinal column.

Implementations described herein include devices and systems for attenuation of increased spinal flexion loads post-fusion that include a transition member. The transition member may have a tension component coupleable to a fused vertebra of a plurality of fused vertebra of a fusion implant and to an adjacent unfused vertebra. The tension component may be tensionable to a selected value. The tension component may modulate a flexion range of motion of the adjacent unfused vertebra as a function of the selected value of tension of the tension component. The transition member may attenuate spinal flexion loads on adjacent unfused vertebra post-operatively.

Some embodiments relate to a pedicle screw implant construct kit, comprising: at least one pedicle screw including a head; an embracing structure shaped and sized for embracing at least a portion of the screw head; an upper fastener for mounting onto the embracing structure, the upper fastener having a polygonal profile at least on a face of the upper fastener facing a direction opposite the screw.

Bone anchors and related systems and methods for spinal deformity correction. In some implementations, two adjacent bone anchors may be advanced into respective, adjacent vertebral bodies of a spinal column. Cancellous bone may be compacted within respective inner chambers of the bone anchors. The inner chambers may comprise at least one of a plurality of bone engaging protrusions and a profile that increases in cross-sectional area, at least in part, from a proximal end of the inner chambers to a distal end of the inner chambers. A tether may then be coupled between the first and second bone anchors to apply a corrective force to at least a portion of the spinal column.

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.