Abstract: A bone anchoring device includes a receiving part with a head receiving portion defining a seat for pivotably receiving a head of a bone anchor, and a rod receiving portion defining a recess for receiving a rod, the recess forming two legs each having an engagement surface for engaging a locking device to lock the rod in the recess, and an expansion limiting member having a surface configured to engage a portion of the receiving part spaced apart from the engagement surfaces of the legs. When the legs are urged radially outwardly, the head receiving portion is urged radially inwardly to compress and lock the head. The expansion limiting member is adjustable from a first configuration relative to the receiving part where the head receiving portion is expandable to permit the insertion of the head, to a second configuration where expansion of the head receiving portion is restricted.

Abstract: A bottom loading fastening system that consists of the polyaxial ball and socket joint used in conjunction with an anchoring bone screw. The system allows attachment of a connector assembly to the anchoring bone screw having a spherical ball connector using a locking ring positioned in a locking ring slot. Upon installation, the locking ring is moved to a ring containment slot to expand a retainer ring, allowing passage of a bone screw spherical ball, the retainer ring forcing the locking ring back to the locking ring slot, thereby permanently attaching the connector assembly to the anchoring bone screw. Movement of the locking ring from the ring containment slot provides an audible sound and tactile indication that the locking ring has secured the connector assembly to the bone screw.

Abstract: A bone screw assembly includes a fastener including a shaft and a head disposed on the shaft. The fastener is configured to be anchored within a subject's bone. A receiving assembly is configured to be movably mounted on the head of the fastener. The receiving assembly includes a receiver disposable around at least a portion of the head of the fastener and defining a channel for receiving a rod member therein. A retaining ring is disposed within the receiver for holding the head of the fastener in the receiver. An insert is disposed in the receiver above the retaining ring. A saddle is disposed in the receiver above the insert. The saddle defines a cradle for seating the rod member in the receiver.

Abstract: A uniplanar bone anchor including a housing and a bone screw is provided. The lower region of the housing defines mating elements that mate with engaging elements on the bone screw to limit movement of the housing relative to the bone screw to a single plane.

Abstract: A coupling device is provided for coupling a rod to a bone anchoring element. The coupling device includes a receiving part having a first end, a second end, a central axis extending through the first end and the second end, and a channel for receiving a rod. The receiving part defines an accommodation space for accommodating a head of a bone anchoring element, the accommodation space having an opening for inserting the head. The coupling device further includes a pressure element arranged at least partially in the accommodation space, the pressure element having a flexible portion to clamp an inserted head, and a clamping element extending at least partially around the flexible portion of the pressure element. The clamping element is configured to move from a first position to a second position in which the clamping element exerts a clamping force onto the pressure element, where the movement includes rotating the clamping element around the central axis.

Abstract: The bottom loading fastening system that consists of the polyaxial ball and socket joint used in conjunction with a bone screw. The system allows attachment to a bone screw using a retaining ring with a blocker ring to assure proper ring positioning. The retaining ring having a continuous inner surface wall and an outer wall having a notch. Upon installation the retainer wall is expanded causing a break at the notch producing an audible and tactile indication that the sufficient force has been applied to set the retainer and blocker rings locking the bone screw to a U-shaped connecting assembly.

Abstract: A polyaxial bone anchor including a housing, a bone screw, and a retainer for pivotably coupling the head of the bone screw to the housing. The retainer is positioned into the bore of the housing and includes a plurality of alternating tabs and slots circumferentially arranged to define a cavity for receiving the head portion of the bone screw therein. The retainer is axially moveable in the housing from a first position in which the head portion is not passable through the lower opening of the retainer to a second position in which the head portion is passable through the lower opening of the retainer.

Abstract: A polyaxial bone screw assembly includes a receiver, a shank, an articulation structure for retaining the shank in the receiver and a compression insert for engagement with a longitudinal connecting member such as a rod. The articulation structure includes substantially spherical convex and concave surfaces that slidably engage both shank and receiver surfaces to provide compound articulation between the receiver and the shank. The receiver includes inwardly directed spring tabs engaging the insert and prohibiting rotation of the insert within the receiver.

Abstract: A modular polyaxial bone screw that incorporates a threaded screw including a head portion and a tulip assembly that selectively “snaps” and locks onto the head portion of the threaded screw in a desired orientation. Thus, the threaded screw may be placed in bone before the tulip assembly is engaged onto the head portion of the threaded screw and a rod is disposed and secured there through using a locking cap, thereby locking the tulip assembly onto the head portion of the threaded screw in the desired orientation.

Abstract: A polyaxial bone anchor has a locking element shaped and configured to allow an anchoring member (e.g., a screw or hook) to polyaxially rotate at large angles about a central axis of the bone anchor before compression locking the anchoring member within an anchor head.

Abstract: A bone screw assembly includes a screw, an outer housing, and an inner housing. The screw includes a shank and a head. The outer housing has a proximal end, a distal end, and a passageway extending longitudinally therethrough. The outer housing defines a saddle at the proximal end thereof for receiving at least a portion of a rod therein. The inner housing is positionable within the passageway of the outer housing. The inner housing has a recessed distal portion for receiving the head of the screw therein. The inner housing also includes a proximal surface defining a substantially V-shaped configuration for receiving rods of different diameters therein.

Abstract: Various exemplary methods and devices are provided for fixing bone anchors to bone. In general, the methods and devices can allow for a bone anchor to be fixed to a bone at a desired angle to a surface of the bone. In an exemplary embodiment, a bone anchor assembly is provided that includes a bone anchor configured to engage bone, a receiver member for seating a head of the bone anchor, and a compression member for securing the bone anchor at fixed angle with respect to the receiver member when the compression member is seated within the receiver member. Corresponding engagement features of the compression member and the receiver member can be engaged in a secured configuration to inhibit or prevent removal of the compression cap from the receiver member and optionally to substantially prevent longitudinal and/or rotational movement of the compression member with respect to the receiver member.

Abstract: A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. The receiver can have crimp tabs, but is devoid of spring tabs and collet-like flexible structures. A down-loadable compression insert (some with lock and release feature), a down-loadable friction fit split retaining ring having super structure for temporary friction fit with an up-loadable shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled.

Abstract: An osseous anchoring implant, various embodiments of which comprise an osseous anchor and a head bearing fixation structure capable of receiving and fixing at least one bar, the head of the implant being traversed by at least one duct, which receives the bar through a lateral aperture, and by a threaded channel, whose axis is not parallel to the axis of the duct, which receives a fixation screw of the bar, the implant being characterized in that it comprises fixation structure of the head on the part of the implant which extends from the osseous anchor, these fixation structures allowing, prior to blocking and fixing, at least a determined mobility of the head around at least one axis not parallel to the axis of symmetry of the osseous anchor. The fixation screw of the bar may comprise a ball and socket at its base.

Abstract: A bone anchoring device includes a bone anchoring element having a shaft and a head; and a receiving part for coupling a rod to the bone anchoring element. The receiving part includes a first portion with a U-shaped recess for receiving the rod, and a second portion for accommodating the head, the second portion having a free end and being flexible so as to allow introduction and clamping of the head. The bone anchoring device also includes a locking ring embracing the second portion. The head is locked by means of exerting pressure with the rod onto the locking ring resulting in compression of the second portion of the receiving part and wherein the locking ring is mounted to the receiving part from the free end of the second portion.

Abstract: An orthopedic implantation device that includes tulip element, a coupling wedge and a locking assembly, and a kit and method of use thereof are described herein. The coupling wedge is located in the bottom of the tulip element. The tulip element includes transverse slots for receiving the rod therein until the rod sits on the coupling wedge. The locking assembly includes a locking cap adapted to be received completely within the tulip element, and having flanges and tabs that cooperate with corresponding grooves in the tulip element. The locking assembly includes a cap set screw adapted to be received within a thru hole in the locking cap element.

Abstract: Coupling assemblies and systems and methods are provided with an anchor member movably coupled with a receiver member extending along a receiver axis. A seat member is movable in the receiver member to assume any one of a plurality of orientations corresponding to an orientation of a connecting element extending through the receiver member transversely to the receiver axis.

Abstract: An implant having a receiver that is adapted to receive a polyaxial screw in the bore and either an internal or external cap. The cap can be an external or internal cap and the implant further has at least one locking aid in the form of at least one of a tactile feedback, a visual feedback or an enhanced fixation between the cap and a rod that is received in the receiver.

Abstract: The disclosure relates generally to embodiments of systems and methods of spinal stabilization. Embodiments include methods that use a dilator to displace tissue proximate to a sleeve. An embodiment of a surgical system can comprise a dilator that may define a working channel from a first opening to a second opening. The dilator can be positioned to displace tissue proximate to the sleeve. The dilator may be shaped to allow a first end of an elongated member to enter the working channel through the first opening and exit the dilator through the second opening to be percutaneously moved to another assembly.

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 for inserting and clamping of the head, and an exterior surface with a curved portion; and a locking ring around the head receiving portion, wherein the locking ring has an interior surface with a curved portion for engagement with the curved portion of the exterior surface of the head receiving portion for locking a position of the head relative to the head receiving portion.

Abstract: An apparatus (10) includes a fastener (16) engageable with a bone portion to connect a longitudinal member (12) to the bone portion. A housing (40) has a first passage (42) configured to receive the longitudinal member (12) and a second passage (44) extending transverse to the first passage. The fastener (16) extends through an opening (50) in the housing (40) into the second passage (44). A longitudinal axis (18) of the fastener (16) is positionable in any one of a plurality of angular positions relative to a longitudinal axis (46) of the second passage (44). A spacer (60) received in the second passage (44) of the housing (40) is engageable with the fastener (16) and the longitudinal member (12). A member (70) applies a force to prevent relative movement between the fastener (16) and the housing (40) and permit manual movement of the fastener (16) relative to the housing (40) against the force when the longitudinal member (12) is disengaged from the spacer (60).

Abstract: A stabilization assembly for stabilizing a vertebra or other bone includes: at least two rods having different diameters; an anchoring element having a shaft and a head; a receiving part for interchangeably receiving any one of the rods to connect the rod to the anchoring element, the receiving part including a rod receiving portion with a channel for receiving the rod, and a head receiving portion having an open end and being flexible to allow introduction and clamping of the head; and a locking ring configured to be arranged around the head receiving portion and to clamp the head in the head receiving portion; wherein the locking ring includes a contact surface configured to contact any one of the at least two rods at at least two distinct contact areas that are spaced apart from one another in a circumferential direction of the rod.

Abstract: An orthopedic bone anchor device is disclosed that includes, in one embodiment, a receiver member, an anchor member and a retaining member. The retaining member may retain the anchor member at least partially in the receiver member. In certain embodiments, the anchor member may have a groove in a head for accommodating part of the retaining member, and/or a multiple lead thread.

Abstract: A bone anchor assembly may include a fixation member securable to a bone, a coupling member, a compressible member and a locking member. The fixation member may be formed monolithically with the coupling member, and the coupling member may have a loop portion shaped to receive the compressible member. The compressible member may comprise a compressible sphere with a bore extending therethrough, the bore shaped to receive an elongated member. The locking member may be actuable through an aperture in the coupling member to urge compression of the compressible member to lock the elongated member in a fixed position. The compressible member may be polyaxially adjustable relative to the coupling member.

Abstract: A polyaxial screw assembly includes a pedicle screw, a coupling, an insert, and a housing. The pedicle screw includes a shank having a helical thread formed thereon and a head at one end. The coupling is positioned on top the pedicle screw and releasably engages portions of the head. The coupling and pedicle screw are positioned within a distal portion of the housing. The pedicle screw is slid through an opening in the insert and the insert is thread into the distal portion of the housing to retain the coupling and the pedicle screw within the housing. The pedicle screw is rotatable and pivotable relative to the housing. Compressing the coupling within the housing locks the pedicle screw in a desired orientation.

Abstract: A polyaxial bone anchor including a housing and a bone screw. A bottom surface of the housing includes an aperture that defines an angulation limit of the bone screw for each azimuthal angle around a longitudinal axis of the housing. The aperture is V-shaped, with the V-shape having converging side walls that define a low-angulation direction near their intersection and a high-angulation direction opposite the low-angulation direction. In some cases, the angulation limit of the bone screw is generally constant over a range of azimuthal angles centered around the high-angulation direction. The housing may be modular, including tabs on one component that are plastically deformed to engage a lip on another component. During assembly, a mandrel advances longitudinally along a bore in the housing, and forces the tabs radially outward toward the lip to a radially outward plastically deformed state.

Abstract: 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 a retainer ring within a retaining ring groove. The retaining ring cooperates with the connector assembly and a saddle that is positioned atop the spherical connector.

Abstract: 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 a retainer ring within a retaining ring groove.

Abstract: A system and associated method are provided for mechanically fixating a region of a skull to a portion of a spine. A plate is provided to contact a region of a skull and be secured thereto. A spinal rod is configured to extend from a location adjacent the plate to a location adjacent at least one vertebra. An adjustable housing is provided to secure the rod to the plate, and has a first position wherein the relative position of the rod to the plate can be adjusted and a second position wherein the relative position of the rod to the plate is secured.

Abstract: A polyaxial bone screw assembly includes a threaded shank body having an upper capture structure, a head and an open, compressible retainer collar. The capture structure and retainer collar are both threaded for rotatable attachment within a cavity of the head. The head has a U-shaped cradle defining a channel for receiving a spinal fixation rod. The head channel communicates with the cavity and further with a restrictive opening that allows for loading the capture structure into the head but prevents passage of the attached retainer collar out of the head. The open retainer collar may be bottom- or top-loaded by compressing open ends of the ring towards each other, the collar springing back into a rounded shape after insertion in the head. The open collar has an external substantially spherical surface that mates with an internal surface of the head, providing a ball joint, enabling the head to be disposed at an angle relative to the shank body.

Abstract: The present invention generally is directed toward a spinal fixation system whereby a coupling element allows the physician to selectively lock or unlock either the connection between the coupling element and a fastener, such as to allow for repositioning of the coupling element, or the connection between the coupling element and an elongate rod. The locking or unlocking of these connections may be made independently and as desired by the physician.

Abstract: A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in a receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. The upper portion expands a retaining member in the receiver cavity to capture the shank upper portion in the receiver. In some embodiment either the retaining member or an insert provide for a friction fit of the shank upper portion in the receiver resulting in non-floppy placement of the shank with respect to the receiver. Some retainers and inserts have a lock-and-release feature. Final locking of the polyaxial mechanism is provided by frictional engagement between the shank upper portion and the retaining member. A pre-assembled receiver, retaining member and optional insert may be popped-on or snapped-on to the shank upper portion prior to or after implantation of the shank into a vertebra.

Abstract: A spinal fixation device may include a bone anchoring member, a rod receiver, and an connection member. The rod receiver may include a channel for receiving a rod projection from a first adjacent fixation assembly. The rod receiver may have a central axis such that the channel is generally perpendicular to the central axis. The connection member may have a rod projection configured to extend to a second adjacent fixation assembly. The rod receiver may be coupled to the connection member and rotatable about the central axis of the rod receiver. The interior fixation assembly may be axially fixed such that the bone anchoring member, the rod receiver and the connection member are not translatably movable relative to each other.

Abstract: A bottom-loading multi-axial bone anchor apparatus is disclosed. The apparatus includes a receiver member, a crown member, a bone anchor and a retaining member. The receiver member defines an upper opening and a lower opening, which may form part of the same opening, a channel, and a groove. The crown member and bone anchor are loaded into the lower opening of the receiver member, and the retaining member fits around the bone anchor and into the groove in the receiver member. The bone anchor is capable of multi-axial positioning with respect to the receiver member. An elongated member is placed in the channel of the receiver member, contacting the crown member, and a compression member is applied via the upper opening. The compression member presses down on the elongated member, which presses down on the crown member and locks the bone anchor between the crown member and the retaining member.

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: The present invention may include a pedicle screw with a multifunctional adaptor, a strain reliever, and a dual-surface cap. The multifunctional adaptor may include a convex pivot ring for improving multi-axial movement and locking stability, an integrated locking mechanism for improving maneuverability, and an integrated compression member for improving the assembly process. The strain reliever may be formed along a neck of the pedicle screw for relieving mechanical stress asserted thereto, and thereby preventing a breakage thereof. The dual-surface cap may provide a slightly sloped surface for reducing the tension of the stabilizing rod. The present invention may also provide for a dynamic adaptor for flexibly connecting two stabilizing rods, which may be versatilely adapted to various pedicle screw configurations.

Abstract: A polyaxial bone screw includes a head member and a shank member. The shank has a capture end and an opposite threaded end for threaded insertion into a vertebra. The head has a U-shaped cradle for receiving a spinal fixation rod and a central bore for receiving the capture end of the shank. An expandible retainer ring with a radial split is snapped onto the capture end of the shank to retain it within the head. The retainer ring has a spherical outer surface which forms a ball joint with a spherical socket cavity within the head to enable the head to be angled relative to the shank. A threaded closure plug is tightened within the cradle to clamp the rod into engagement with a knurled dome on the capture end of the shank to secure the rod relative to the vertebra.

Abstract: A spinal fixation assembly and capless multi-axial screw system and method are shown. The assembly comprises a receiver having a rotary lock which in one embodiment includes a plurality of channels which urge and lock the elongated member to the screw using a bayonet type connection.

Abstract: The present teachings provide one or more surgical implements for repairing damaged tissue, such as in the case of a spinal fixation procedure. A multiplanar bone anchor system for a fixation procedure is provided. The system can include a bone fastener. The bone fastener can include a head and a second end adapted to engage an anatomy. The bone fastener can extend along a longitudinal axis. The system can also include a coupling arrangement coupled to the head of the bone fastener so that the bone fastener is rotatable about the longitudinal axis to define a first plane of motion. The system can further include a saddle, which can be coupled to the coupling arrangement. The saddle can be movable relative to at least one of the bone fastener and the coupling arrangement to define a second plane of motion.

Abstract: An assembly for connecting a support element to a bone. The assembly comprises: a bone screw having a head at one end of a threaded shaft; and a clamp comprising: a base at a first end of the clamp delimiting an opening for receiving the head of the bone screw; and at least two side members extending from the base towards a second end of the clamp. The head of the bone screw and the clamp are configured to allow the head of the bone screw to be inserted into the base from the direction of the first end at a first orientation of the base to the bone screw, and to retain an inserted bone screw within the base at a second orientation of the base relative to the bone screw. This allows the screw to be inserted into the bone without requiring prior assembly of the screw and clamp. It also allows later revision whereby the clamp can be removed from the screw without requiring an implanted screw to be removed from the bone.

Abstract: A spine stabilization system having a dynamic screw comprises at least one bone anchor assembly comprising a receiver member and a bone engaging member pivotably connected to the receiver member. A bearing is provided in the receiver member that engages a portion of the bone engaging member. An elongated connecting member is connected to the receiver member. A retention member insert is provided within the receiver member between the elongated connecting member and the bearing. The retention member is configured to secure the bearing within the retention member.

Abstract: A polyaxial screw assembly includes a pedicle screw, a coupling, an insert, and a housing. The pedicle screw includes a shank having a helical thread formed thereon and a head at one end. The coupling is positioned on top the pedicle screw and releasably engages portions of the head. The coupling and pedicle screw are positioned within a distal portion of the housing. The pedicle screw is slid through an opening in the insert and the insert is thread into the distal portion of the housing to retain the coupling and the pedicle screw within the housing. The pedicle screw is rotatable and pivotable relative to the housing. Compressing the coupling within the housing locks the pedicle screw in a desired orientation.

Abstract: A medical implant assembly includes a polyaxial bone anchor having a shank with an upper portion, a receiver, a retainer for holding the shank upper portion in the receiver, a lower compression insert with surfaces for closely receiving an elongate connecting member and a closure structure that may independently engage the lower compression insert to lock the shank with respect to the receiver while selectively not locking the elongate member. Projections or splines of the shank upper portion mate with holding pockets on the retainer. The bone anchor includes a shank upper surface exclusively engaging the lower compression insert that is spaced from the retainer, the retainer and shank being configured for polyaxial motion with respect to the receiver prior to locking.

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 receiver has a U-shaped channel for receiving a spinal fixation rod. The shank upper portion is designed to directly frictionally engage the spinal fixation rod when a closure structure operably urges the rod toward the upper portion, fixing the bone screw shank body in a selected angular orientation with respect to the receiver.

Abstract: System and methods are provided that include a plate member engageable to the spinal column with an anchor assembly. The anchor assembly includes a coupling member having a post extending through at least one opening of the plate member and an anchor member pivotally captured in a receiver member of the coupling member below a lower surface of the plate member. A locking member secures the plate member to the coupling member.

Abstract: A fastener assembly including an existing polyaxial pedicle screw that has been previously installed in a spinal structure, the polyaxial pedicle screw including a polyaxial head to which a prosthetic member is secured, a fastening portion fastened to the polyaxial head over the prosthetic member, and a connector element that extends from the fastening portion, the connector element being connected to another spinal structure.

Abstract: A bone anchor assembly is provided, which may be used in cervical, thoracic, lumbar or sacral areas of the spine or other orthopedic locations. The anchor assembly includes a bone anchor, a receiver mounted to the bone anchor, a saddle within the receiver, a spacer within the receiver, and an engaging member. The receiver extends along a central longitudinal axis proximally away from the bone anchor. A rod or other elongated connecting element is received in a passage of the receiver in contact with the saddle, and the engaging member engages the connecting element against the saddle, which engages the saddle against the spacer, which in turn engages the proximal head of the bone anchor in the receiver. The orientation of the saddle in the receiver is adjustable to correspond to the orientation of the connecting element relative to the central longitudinal axis of the receiver.

Abstract: A novel surgical screw is presented as a polyaxial, multiaxial, or monoaxial screw. The polyaxial screw allows versatile angulation between a bone anchor section and a screw body and allows the surgeon to attach a rod to the invention in a top-loading manner and manipulate the rod to accommodate a patient's body and the surgical goals. The screw uses a rod saddle to seat a rod, and permits the surgeon to sagitally manipulate the rod. After implantation of the screw and insertion of the rod, a locking screw is used to fix the angle and position of the rod and screw body.

Abstract: Methods, systems, devices and tools for placing bone stabilization components in a patient are provided. The systems and devices have a reduced number of discrete components that allow placement through small incisions and tubes. More particularly, the present invention is directed to screws for use in systems and methods of treating the spine, which eliminate pain and enable spinal motion, which effectively mimics that of a normally functioning spine. Methods are also provided for installation of the screw and other subject systems.

Abstract: A polyaxial bone screw includes a head member and a shank member. The shank has a capture end and an opposite threaded end for threaded insertion into a vertebra. The head has a U-shaped cradle for receiving a spinal fixation rod and a central bore for receiving the capture end of the shank. An expandable retainer ring with a radial split is snapped onto the capture end of the shank to retain it within the head. The retainer ring has a spherical outer surface which forms a ball joint with a spherical socket cavity within the head to enable the head to be angled relative to the shank. A threaded closure plug is tightened within the cradle to clamp the rod into engagement with a knurled dome on the capture end of the shank to secure the rod relative to the vertebra.