Abstract: A coupling device for securing an elongate member to the spine is provided. The coupling device comprises a compressible inner member that secures an anchor member therein when the inner member is axially shifted within an outer member. The elongate member is retained within the device by an axially inserted locking member, and may be secured independently of the anchor member. The coupling device and anchor may be configured to provide increased angulation of the anchor with respect to the coupling device. For instance, anchor member may have an offset head portion in order to provide normal pivoting of the coupling device when the anchor is attached to bone at an angle.

Abstract: A receiving part for receiving a rod for coupling the rod to a bone anchoring element includes a receiving part body including a rod receiving portion with a channel for receiving a rod, and a head receiving portion for accommodating a head of a bone anchoring element, the head receiving portion having an open end and being flexible so as to allow introduction and clamping of the head, the head receiving portion having an exterior surface with a tapered portion; and a locking ring around the head receiving portion and including an interior surface with a curved portion configured to engage the tapered portion of the exterior surface of the head receiving portion to clamp the head.

Abstract: An anchoring device for attaching an upper vertebra adjacent to a lower vertebra comprises a clamp having a first end and a second end opposite the first end, adapted to be positioned around upper and lower lateral masses of the adjacent vertebrae, and a fastener which in an installed position engages opposite ends of the clamp and which engages adjacent vertebrae thereby attaching the adjacent vertebrae together.

Abstract: A receiving part for receiving a rod for coupling the rod to a bone anchoring element, the receiving part including: a receiving part body including a rod receiving portion with a channel for receiving a rod, and a head receiving portion for accommodating a head of a bone anchoring element, the head receiving portion having an open end and being flexible for inserting and clamping of the head; a locking ring around the head receiving portion to exert a first force onto the head receiving portion to lock the head therein; and a pre-locking ring separate from the locking ring and around the head receiving portion to exert a second force less than the first force onto the head receiving portion to clamp the head in a temporary pre-locking position.

Abstract: A method of assembling a bone anchor assembly is presented. The bone anchor assembly includes a bone anchor and housing configured to receive the bone anchor and a longitudinal member. The bone anchor is inserted into a passage in the housing and material is swaged to retain the bone anchor in the housing. The material that is swaged is a portion of the housing or additional material added to the assembly.

Abstract: A locking mechanism (100) and method of fixation, such as the fixation of a fixation device (104) like a bone screw and of a rod (106) to the spine. The locking mechanism (100) includes a body (102), an insert (108, 308), a rod seat (110, 310) and a set screw. The body (102) includes a bottom portion (114) configured to receive the fixation device (104) and the insert (108, 308) but prevents the insert (108, 308) and fixation device (104) from passing therethrough once the insert (108, 308) and fixation device (104) are engaged. The body (102) further includes a side portion (120) configured to receive the rod (106). Between the rod (106) and the insert (108, 308) is a rod seat (110, 310).

Abstract: A poly-axial bone fastener assembly having a collar and a bone fastener can be coaxially locked to prevent poly-axial movements of the collar relative to the bone fastener while permitting the collar to rotate about an axis of the bone fastener, thereby combining the functions and advantages of a poly-axial bone screw and a fixed angle bone screw. Some embodiments of a coaxial locking mechanism may include a c-clip with a locking pin, a c-clip with hooks, a split ring with square corners, a pin that spins inside the collar, pins that travel about a neck of the bone fastener, a coaxially locking top that screws into the collar over a head of the bone fastener, and a top nut that threads onto the head of the bone fastener inside the collar to trap a flange of the collar between a shoulder of the bone fastener and the top nut.

Abstract: A pedicle screw assembly including a bone fastener having a lower end for engaging bone and an upper end remote from the lower end; a head having a rod-receiving channel attached to the upper end of said bone fastener; a spinal rod insertable into the rod-receiving channel of said head, said spinal rod having an outer surface extending between first and second ends thereof, wherein at least one of the first and second ends has a reduced diameter section. A spinal rod having an outer surface extending between a first end and a second end thereof; wherein the outer surface of said spinal rod has a reduced diameter section at least one of the first and second ends.

Abstract: A porous PEEK implant system which may provide tissue ingrowth throughout the body of the implant. The implant may comprise a solid or porous PEEK core. The porous PEEK implants may be of general shape and size but provide the structure necessary to carry out the function of the implant. The porous PEEK implant pores may be seeded with agents to encourage tissue ingrowth as well as other agents such as antibiotics, anesthetics, analgesics and the like.

Abstract: A bone fixation assembly includes a plurality of bone fixation elements that each include a bone anchor configured to be implanted into underlying bone, such as a vertebra. Each bone anchor is received in an anchor seat, and the anchor seats are joined by a fixation rod so as to operatively couple and fix the position and orientation of the vertebrae relative to each other. The bone anchor is free to rotate relative to the anchor seat, and is also free to pivot in a desired direction relative to the anchor seat.

Abstract: A cannulated screw which maintains compression at the interface between two or more materials in a medical or other setting to effectively secure bone to bone while minimizing separation between the bones and the securement interface. The cannulated screw has a flattened tip, which enables the cannulated screw to more readily bore or self-tap into bone or other material. The flattened tip of the cannulated screw comprises a plurality of cutting teeth which facilitate boring of the flattened tip of the cannulated screw into the material into which the screw is being inserted. In one embodiment, three progressive cutting teeth are provided on the flattened tip of the cannulated screw.

Abstract: A method of conducting a surgical procedure including implanting an anchor into a bone, wherein the anchor comprises a receiving portion and a screw, the screw including a screw head contained within the receiving portion and pivotally engageable with a surface of the receiving portion, and wherein the receiving portion and the screw comprising a different material. The method further includes selecting a rod from a group of rod types and coupling the rod with the receiving portion to stabilize a position of a portion of the spine.

Abstract: The present invention generally provides a polyaxial fixation device having a shank with a spherical head formed on a proximal end thereof, and a receiver member having an axial passage formed therein that is adapted to polyaxially seat the spherical head of the shank. The polyaxial bone screw further includes an engagement member that is adapted to provide sufficient friction between the spherical head and the receiver member to enable the shank to be maintained in a desired angular orientation before locking the spherical head within the receiver member.

Abstract: A screw and coupling element assembly for use with an orthopedic rod implantation apparatus includes a screw with a head and a shaft extending from the head, a coupling element with a seat within which the head is seatable such that the shaft protrudes from the coupling element, and a locking element mateable with the coupling element and when mated is selectively movable through a plurality of positions including unlocked and locked positions. When in the unlocked position, the locking element presents a rod-receiving channel and the head is movable in the seat such that the shaft is directable in a plurality of angles relative to the coupling element. When in the locked position, a rod disposed within the rod-receiving channel is fixed relative to the coupling element and the head is immovable in the seat such that the shaft is fixed at an angle relative to the coupling element.

Abstract: A polyaxial ball and socket joint that can be locked into a fixed position. The fastening system consists of the polyaxial ball and socket joint used in conjunction with a bone screw having threads on one end for use in anchoring to the spine and a spherical connector on the other end operating as a pivot point about which a connecting assembly moves in a polyaxial fashion. A substantially U-shaped connecting assembly has a lower receptacle that operates as a socket for housing an upper retainer ring and a lower split retaining ring. The socket is receptive to the spherical connector which is inserted through the lower split retainer ring causing a momentary displacement thereof which allows for the positioning of the spherical connector between the upper and lower retainer rings.

Abstract: An anchor with a non-threaded securing mechanism for attaching an elongated member to a bone. The anchor includes a receiver, shaft, and securing mechanism. The receiver includes spaced-apart arms that form a channel sized to receive the elongated member. The shaft extends from the receiver and is configured to engage with the bone. The securing mechanism, including a base and an insert, attaches to the receiver to capture the elongated member in the channel. The base is configured to attach to the arms and includes an aperture that receives the insert. The insert extends through the aperture and may contact against the elongated member.

Abstract: A bone fixation assembly and associated method. The bone fixation assembly includes a bone fastener having a head and a bone-engaging portion, a receiver defining an opening along a first axis for receiving the bone fastener at a variable angle, and at least one supporting augment coupled to the bone fastener. The receiver has an inner articulation surface at a lower portion of the opening and matingly articulates with the supporting augment.

Abstract: A system for stabilization of the spinal column, including an elongate support member extending along an axis and a plurality of anchor members configured for anchoring to respective vertebrae. A first of the anchor members is engaged to the support member in a manner that substantially prevents axial movement of the support member relative to the first anchor member, and a second of the anchor members is engaged to the support member in a manner that allows substantially unconstrained axial movement of the support member relative to the second anchor member. In a further embodiment, a third of the anchor members is engaged to the support member in a manner that also allows substantially unconstrained axial movement of the support member relative to the third anchor member, with the second and third anchor members positioned on opposite sides of the first anchor member.

Abstract: A system and method for ameliorating spinal column anomalies, such as scoliosis, while accommodating growth of juvenile patients, includes pedicle screws and a spinal rod of non-circular cross section. Each pedicle screw includes spinal rod engagement mean for achieving a slide-only engagement between each segment of said spinal rod that is respectively engaged with the pedicle screw. Pedicle screws are thereby allowed to slide longitudinally along the spinal rod as attached vertebrae move during growth, while movement in other directions is arrested in order to preserve a proper orientation of involved vertebrae to maintain scoliotic correction in three dimensions.

Abstract: A device to attach an elongated member to a bone in a patient with the device including a receiver with arms that are spaced apart that form a channel sized to receive the elongated member, and a groove on an inner surface of at least one of the arms. A shaft may be operatively connected to the receiver and configured to attach to the bone. A securing mechanism is attached to the receiver that includes an outer member and an inner member. The outer member may include a bore and a non-threaded exterior that may be configured to engage with the groove to attach the securing mechanism to the receiver. The second member may be sized to fit in the bore and move axially along the bore in a non-rotational manner. The second member may also include a compressible extension sized to fit in the bore when the extension is moved in the bore and to expand to a width greater than the bore when the second member extends outward beyond the bore.

Abstract: Devices and methods include a multi-axial anchor assembly engageable to a vertebra and a connecting element positionable through a receiver of the anchor assembly. The anchor assembly includes a flexible member between the receiver and an anchor member of the anchor assembly, thereby providing a flexible joint in the anchor assembly for allowing limited movement after primary multi-axial capability between the receiver and the anchor member has been arrested.

Abstract: A lock screw assembly for use with a pedicle screw assembly comprises a lock screw and an upper saddle. The lock screw includes a fastening tool engaging structure at a first end portion thereof and an upper saddle receiving structure at a second end portion thereof. The upper saddle is engaged with the upper saddle receiving structure of the lock screw in a manner allowing the upper saddle to rotate about a centerline axis of the lock screw. A plurality of intersecting spine rod receiving channels extend through a spine rod engaging portion of the upper saddle in a manner such that an outwardly-extending spine rod engaging structure is provided between adjacent ones of the spine rod receiving channels. Upper and lower surfaces of each spine rod engaging structure are acutely angled with respect to each other and wherein a channel edge defined between the surfaces is sharply pointed.

Abstract: The present invention provides a bone screw which can be used for fixation and/or fastening of prosthetic devices or instruments to bone tissue whose structure or dimensions differ from one region to another. In particular, the present invention provides a bone screw which is designed to optimize purchase in both the cancellous and cortical regions of a vertebral body. In an exemplary embodiment, the bone screw has a distal portion and a proximal portion in which the diameter of the thread on the proximal portion of the screw is greater than the diameter of the thread on the distal portion of the screw.

Abstract: The present invention relates to an alternatively monoaxial and polyaxial pedicle or other similar surgical screw that can be used in a polyaxial manner and then locked or otherwise secured at a desired angle or orientation, i.e. used in a monoaxial manner, prior to engaging a rod or other similar stabilization member with the pedicle or other similar surgical screw. In other words, the present invention provides a pedicle or other similar surgical screw that can be selectively used in either a monoaxial or polyaxial configuration, as is desirable in a particular application or at a particular point of a given surgical procedure.

Abstract: The present application is directed to pedicle-based posterior stabilization members and methods of stabilizing vertebral members. The stabilization members generally include a body with first and second connector sections. The first connector section is configured to connect to a pedicle of a first vertebral member. The second connector section is configured to contact an adjacent vertebral member. The second connector section may be positioned at an end of the body, or an intermediate section away from the end.

Abstract: The present application is directed to connectors for attaching an elongated member to a bone. The connectors may include a receiver that is attached to an anchor. The receiver may include a base and outwardly-extending arms that form a channel to receive the elongated member. The base may include an opening that extends into a receptacle. The opening may include a first section in an inferior side of the receiver, and a cut-out in a lateral side. During attachment, the anchor may be positioned relative to the receiver such that a head of the anchor may be inserted into the first section and a shaft of the anchor may be inserted into a second section. After insertion, the anchor is rotated to move the shaft out of the cut-out while the head remains in the receptacle. A wedge is then attached to the receiver over the cut-out to prevent the anchor from escaping.

Abstract: A tulip assembly configured to be coupled to a head of a bone fixation device includes at least one inner member configured to fix the tulip assembly to the head of a bone fixation device, and an outer member including at least one engagement surface configured to selectively fix a rod in the tulip assembly via rotation of the outer member, wherein the fixation of the tulip assembly to the head of the bone fixation device is independent of the fixation of a rod in the tulip assembly.

Abstract: A low profile bone screw system includes a retainable washer and a low profile bone screw having a smooth conical head for insertion into the washer. The washer has an axial bore with a conical portion for fully seating the screw head and a smooth outer surface shaped like the head of a conventional compression bone screw head. Washer dispensing units are also provided.

Abstract: A cannulated compression screw is used as an orthopedic implant and has a threaded distal end with an insertion tip that includes at least one and preferably two, three or four flutes to allow the screw to be self-tapping. Optionally, the screw also includes one or more reverse cutting flutes proximal to the insertion tip. The distal threads are cancellous threads having a generally constant minor diameter and a generally constant major diameter and a generally constant thread pitch. An intermediate portion of the screw is non-threaded and the proximal end includes a compression wedge or taper that has at least one, and preferably two to five flutes that terminate before the top of the screw. The proximal end further includes a radiused bevel to the terminal surface that includes a hexagonal torque driving recess. The diameter of the non-threaded shaft section is constant distal from the compression wedge to the distal tip where it defines the minor diameter of the threaded portion.

Abstract: A bone screw includes an elongate shaft extending longitudinally between a proximal end and an opposing distal end, the shaft bounding a first passageway at least partially extending between the proximal end and the distal end, the shaft being comprised of a radiolucent material. A core is disposed within the first passageway of the shaft, the core being comprised of a radiopaque material. A rounded head or a substantially U-shaped collar is either integrally formed with or is rigidly attached to the proximal end of the shaft.

Abstract: The present application is directed to connectors for attaching a vertebral rod to an anchor. The connectors may include a body with a first channel to receive the vertebral rod and a second channel to receive the anchor. A cradle may be positioned in the body to contact the vertebral rod. The cradle may be pivotally positioned in the body to accommodate a vertebral rod that is at various angular positions within a predetermined plane. A set screw may engage with the body to secure the vertebral rod to the body and the body to the anchor.

Abstract: A polyaxial screw assembly includes an internal load dampening mechanism for sharing and dampening loads between at least one screw member and at least one rod member interconnected by the assembly. A method of interconnecting the orthopedic screw with the rod by dampening with a body member interconnecting the screw to the rod.

Abstract: A polyaxial screw assembly includes an internal load dampening mechanism for sharing and dampening loads between at least one screw member and at least one rod member interconnected by the assembly. A method of interconnecting the orthopedic screw with the rod includes dampening with a body member interconnecting the screw to the rod.

Abstract: A spinal fixation assembly for connecting an elongate member along a region of a spinal column with a plurality of fasteners is disclosed. The spinal fixation assembly comprises a threaded fastener having a first threaded end region and a second end region configured to receive an elongate member, such as a rod. A locking member is included for securing the elongate member within the second end region. The second end region and the locking member include elastomeric members that contact the elongate member to allow for a degree of dynamic movement.

Abstract: A modular anchoring device including a threaded shank for anchoring within a vertebra, an intermediate element and a head portion configured to receive and secure a rigid or non-rigid stabilization rod. The threaded shank, the intermediate element and the head portion of the anchoring device are cannulated to permit percutaneous implantation of the device. The intermediate portion is designed to be removable from the threaded shank portion subsequent to implantation of the anchoring device to enable substitution of another intermediate element having different dynamic characteristics.

Abstract: A modular anchoring device including a threaded shank for anchoring within a vertebra, an intermediate element and a head portion configured to receive and secure a rigid or non-rigid stabilization rod. The threaded shank, the intermediate element and the head portion of the anchoring device are cannulated to permit percutaneous implantation of the device. The intermediate portion is designed to be removable from the threaded shank portion subsequent to implantation of the anchoring device to enable substitution of another intermediate element having different dynamic characteristics.

Abstract: A modular dynamic pedicle screw system including anchoring device having a threaded shank for anchoring within a vertebra, an intermediate element and a head portion configured to receive and secure a rigid or non-rigid stabilization rod. The threaded shank, the intermediate element and the head portion of the anchoring device are cannulated to permit percutaneous implantation of the device. The intermediate portion is designed to be removable from the threaded shank portion subsequent to implantation of the anchoring device to enable substitution of another intermediate element having different dynamic characteristics. The dynamic stabilization system includes an adjustable torque limiting device that is interchangeable between a tap device and a screw driver.

Abstract: A vertebral stabilization assembly for stabilizing a vertebral segment. The assembly includes a vertebral anchor, a first stabilization member, a second stabilization member, and a threaded fastener. A post of the first stabilization member is configured to be positioned in a first socket of the head portion of the vertebral anchor and a post of the second stabilization member is configured to be positioned in a second socket of the head portion of the vertebral anchor. The threaded fastener is configured to threadedly engage a threaded opening of the head portion such that when the threaded fastener is threaded into the threaded opening, the threaded fastener engages both the post of the first stabilization member and the post of the second stabilization member.

Abstract: A threaded rod or pedicle screw for insertion into the pedicle portion of a vertebra and having at its exposed end a second threaded rod rigidly connected in a generally parallel orientation to the longitudinal axis of the pedicle screw. The second rod being offset from the longitudinal axis of the pedicle screw and having a locking pin or arm and retaining nut for affixing a rod to the pedicle screw substantially over and aligned with the longitudinal axis of the pedicle screw.

Abstract: A fastener assembly for a spinal fixation system that is particularly useful in treatment of pediatric and small-statured patients includes a fastener, an attachment member, and a locking member. The fastener has a lower portion for contacting a bone and an upper portion integral with the lower portion. The upper portion has two open channels. Each channel is configured and dimensioned to receive a portion of a longitudinal or connecting member along its circumference. The attachment member is positionable on the fastener and at least partially covers the channel that receives the longitudinal or connecting member. The locking member is operatively associated with the upper portion of the fastener and secures the attachment member and the longitudinal or connecting member to the fastener.

Abstract: A dynamic bone anchor for anchoring a spine stabilization assembly which supports the spine while providing for the preservation of spinal motion. The dynamic bone anchor provides load sharing while preserving range of motion and reducing stress exerted upon the bone anchors and spinal anatomy. The dynamic bone anchor includes a deflectable post connected by a ball-joint to a threaded anchor. Deflection of the deflectable post is controlled by a compliant ring. The force/deflection properties of the dynamic bone anchor may be adapted to the anatomy and functional requirements of the patient. The dynamic bone anchor may be used as a component of a dynamic stabilization system which supports the spine while providing for the preservation of spinal motion.

Abstract: Systems and methods for reducing spinal stabilization rods. One embodiment provides an instrument including a body (defining a threaded slot for receiving the spinal stabilization rod), an alignment feature, and a flange (for mounting the instrument on a bone anchor), each of which can correspond to portions of the bone anchor. The alignment feature can align the threads of the instrument and bone anchor to form substantially continuous threads. The alignment features can be a pin and a hole oriented radially with respect to the instrument. An actuator can actuate the instrument alignment features toward, or away from, the instrument body. An actuator slot can correspond to the instrument slot. The threads of the instrument slot can include a thread diameter transition portion. In some embodiments, the instrument threads can include an anti-splay feature which mitigates reaction moments arising from the reduction of the spinal stabilization rod.

Abstract: A versatile offset connector for connecting components of a dynamic stabilization system which supports the spine while providing for the preservation of spinal motion. Alternative embodiments can be used for spine fusion. Embodiments of the dynamic stabilization system have an anchor system, a deflection system, a vertical rod system and a connection system. The anchor system anchors the construct to the spinal anatomy. The deflection system provides dynamic stabilization while reducing the stress exerted upon the bone anchors and spinal anatomy. The connection system includes coaxial connectors and offset connectors which adjustably connect the deflection system, vertical rod system and anchor system allowing for appropriate, efficient and convenient placement of the anchor system relative to the spine.

Abstract: A dynamic bone anchor for anchoring a spine stabilization assembly which supports the spine while providing for the preservation of spinal motion. The dynamic bone anchor provides load sharing while preserving range of motion and reducing stress exerted upon the bone anchors and spinal anatomy. The dynamic bone anchor includes a deflectable post connected by a ball-joint to a threaded anchor. Deflection of the deflectable post is controlled by a compliant member. The dynamic bone anchor may be used as a component of a dynamic stabilization system which supports the spine while providing for the preservation of spinal motion. The dynamic bone anchor has splines on the outside of the housing to facilitate installation and the secure attachment of spine stabilization components.

Abstract: A dynamic bone anchor for anchoring a spine stabilization assembly which supports the spine while providing for the preservation of spinal motion. The dynamic bone anchor provides load sharing while preserving range of motion and reducing stress exerted upon the bone anchors and spinal anatomy. The dynamic bone anchor includes a deflectable post connected by a ball-joint to a threaded anchor. Deflection of the deflectable post is controlled by a compliant ring. The force/deflection properties of the dynamic bone anchor may be adapted to the anatomy and functional requirements of the patient. The dynamic bone anchor may be used as a component of a dynamic stabilization system which supports the spine while providing for the preservation of spinal motion.

Abstract: A dynamic spinal stabilization component which supports the spine while providing for the preservation of spinal motion. The component is selectably attachable to a bone anchor for implantation in a bone of the spine. The component and bone anchor provide load sharing while preserving range of motion and reducing stress exerted upon the bone anchors and spinal anatomy. The dynamic spinal stabilization component includes a deflectable post connected by a ball-joint to a threaded anchor. Deflection of the deflectable post is controlled by a centering spring. The force/deflection properties of the dynamic bone anchor may be adapted to the anatomy and functional requirements of the patient. The dynamic spinal stabilization component may be used as a component of a dynamic stabilization system which supports the spine while providing for the preservation of spinal motion.

Abstract: A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in a receiver and retained within the receiver by a retaining structure in the form of an open ring. The retaining structure is compressible, having an opening with two ends that may be pressed toward one another. The receiver has a U-shaped cradle defining a channel for receiving a spinal fixation rod. The receiver channel communicates with a cavity partially defined by an upper spherical surface and a substantially cylindrical surface communicating with a bottom opening of the receiver that allows for bottom loading the shank upper portion and the compressed retaining structure into the receiver, but prevents passage of the retaining structure out of the receiver once the retaining structure expands to an original form thereof and thus retains the shank upper portion within the cavity.

Abstract: A spinal fixation system includes a rod and anchor devices that include a bone engaging fastener having a head defining a spherical socket. A ball insert is placed within the socket and rotated so that the ball insert is juxtaposed with the socket. The anchor device further includes a yoke defining a yoke channel for receiving the rod and a stem engaged to the ball insert captured within the socket. A sleeve disposed between the yoke channel and the fastener head supports the rod. A set screw is operable to clamp the rod against the sleeve and draw the insert into engagement within the socket. A friction element in the form of a wave spring is disposed between the yoke and the fastener head is configured to releasably retain the yoke in at least one discrete position relative to the fastener.

Abstract: A device pivotally connects two stabilizing parts to a bone. The device comprises at least one bone fixing element with a central axis, an anchor part designed to be fixed in or onto the bone, and a head part that can be attached to both stabilizing parts. The two stabilizing parts are located axially one below the other. Each stabilizing part has a cavity there through running coaxially to the central axis. A clamping element, which can be elastically deformed transversely to the central axis, is rotatably mounted in each cavity. The clamping element has a central bore running coaxially to the central axis for receiving the head part. The device comprises at least one wedge or cone that can be axially clamped in the central bores, enabling the head part of the bone fixing element to be removably fixed in at least one of the stabilizing parts.

Abstract: Methods and systems for reducing spinal stabilization rods. In one embodiment, a method can include attaching a collar to a boney structure. The collar can include a body and an extension, each including arms further defining threaded slots. A separation member can couple the body and the extension to each other. The method can include reducing the rod using the collar and separating the extension from the body by applying a torque to the extension. The separation of the extension from the body can be accomplished with one substantially continuous motion and can leave tissues adjacent to the collar substantially undisturbed. The arms of the extension can be prevented from splaying, thereby mitigating a moment during the reduction of the spinal stabilization rod through the extension. Thus, the separation member can transmit tensile forces and certain amounts of torques between the body and the extension.