Abstract: A polyaxial bone screw assembly includes a threaded shank body member having an upper portion with an internal drive and, alternatively, a laterally extending alignment rib or fin. The bone screw assembly also includes a lockable receiver coupling member, an open retainer ring member having a slit or gap and a compression insert member. An inset conical or cylindrical surface on the shank upper portion frictionally engages a similarly shaped inner surface of the retainer ring. The receiver includes a restrictive lower opening that allows for uploading the shank upper portion and compressed retainer ring into the receiver cavity, but prevents passage of the retainer ring out of the receiver once the ring inner surface engages the conical surface of the shank upper portion.

Abstract: Provided is a novel mono-axial taper lock screw for connecting a connecting rod to bone. The screw is capable of being secured to the underlying bone while the screw head adapted to securely hold a connecting rod is rotated about the longitudinal axis of the screw to facilitate a stable connection to the connecting rod. The screw head can be partially locked to hold the device in place while permitting manipulation of the spine. The screw head can then be fully locked securing the connecting rod into a selected position. The screw is configured for easy insertion and connection as well as easy removal and disconnection from the connecting rod. Also provided is a bone fragments. A method of fixing bones or bone fragments is also provided.

Abstract: A bushing for a bone screw assembly includes a distal portion, a receiver portion, and a proximal portion. The distal portion includes a distal engagement surface that engages with a head of a bone screw. The receiver portion receives a fixation rod. The proximal portion includes a proximal engagement surface that engages with a locking member and a deformable portion that deforms from a first configuration to a second configuration based on a force applied by the locking member.

Abstract: A bone screw extension assembly for use in placing a connecting rod percutaneously into tissue of a patient comprises a multi-axial bone screw and a screw extension releasably coupled to yoke of the bone screw. The screw extension includes coaxially disposed outer sleeve and inner sleeves that are movable axially relative to each other. A screw engaging member projects radially from the distal end of the inner sleeve and is configured to releasably engage an extension coupling surface on the inner surface of opposed upstanding arms of the yoke. A securement member including cooperative surfaces is defined adjacent the distal end of the inner and outer sleeves that is operable upon relative axial movement of the inner and outer sleeves to radially secure the sleeves together for minimization of splaying and to thereby maintain the engagement of the screw engaging member and the bone screw.

Abstract: A bone anchor (100) for attaching a rod (108) to a bone has an anchor member (106) for attachment to the bone and an anchor head (104) having a U-shaped opening for receiving the rod. The bone anchor also includes a locking cap (102) that has a main body (900) and a set screw (1000). Advantageously, in one embodiment the locking cap preferably is designed such that a single tool can be used to lock the locking cap in place on the anchor body preferably with a 90° turn and preferably then drive the set screw to clamp the rod. The locking cap also preferably non-threadingly engages the anchor body. The anchor body preferably has an inclined surface on its top surface which elastically deflects extending tabs on the main body to secure the locking cap to the anchor body. A method of implantation and assembly of the bone anchor are also described.

Abstract: A polyaxial pedicle screw may include a receiving head having a transversal U-shaped passage, and a shank having a threaded portion external to the receiving head, and a bulging end rotatable housed within the receiving head. The polyaxial pedicle screw may include a locking insert housed within the receiving head and matable with the bulging end, for locking it into position, and a set-screw engaged in the distal aperture for locking a connecting rod received within the transversal U-shaped passage. The receiving head of the polyaxial screw may include a lateral aperture, the lateral aperture exposing a contact surface of the locking insert in such a way that external pressing component can act on the contact surface to maintain the locking insert into its locking position.

Abstract: Disclosed are spinal fusion assemblies for use in skeletal systems. The assembly includes a coupling element that can be coupled to a fixation element, such as, for example, a screw with a head that removably mates with the coupling element. The coupling element and fixation element are configured to be coupled to an elongate stabilizer, such as a rod, that is positioned between a top and a bottom saddle. A compression member, such as a compression nut, is configured to mate with the coupling element and provides a compressive force to the top and bottom saddles to secure the elongate stabilizer therebetween. The top and bottom saddles are movably positioned within the coupling element such that they can gradually reposition and self-align into a secure engagement with the stabilizer as the compression member provides the compressive force.

Abstract: An orthopedic bone fixation device including an anchor member having a cavity and an insert member. The anchor member retains the insert member at least partially or entirely in the cavity. The insert member has an insert aperture for accommodating part of a screwdriver or other device.

Abstract: A dynamic spinal stabilization component which supports the spine while providing for the preservation of spinal motion. The component may be integrated in 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 an axially compressible 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: Disclosed are several embodiments directed to a flexible fixation device and method to provide adequate purchase into bone at angles that are awkward for properly engaging inflexible and rigid screws. In one instance, the fixation device is comprised of a head to effect engagement of the device and to acts as an insertion-stop for the device, as well as a helical portion of a suitable cross-sectional geometry to allow for adequate purchase into bone. The helical portion provides fixation as the helical form engages the bone over a relatively large surface area relative to the size of the entry point. The helical portion may be variously configured to resemble, for example, a cork screw, a coiled spring, and so forth. Most variations offer both flexibility (to make angled insertion achievable) while still retaining enough helical-directional rigidity to achieve the desired implantation and fixation.

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: A bone anchor includes a distal bone engaging portion, a proximal portion extending from the distal bone engaging portion that includes a thread profile, and a mating element that threadingly engages the thread profile of the proximal portion. A retention feature between the mating element and the proximal portion deformably engages at least one of the mating element and the proximal portion to resist the mating element from moving relative to the proximal portion of the bone anchor.

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 releasable detent defined between the yoke and the fastener head is configured to releasably retain the yoke in at least one discrete position relative to the fastener. Portions of the releasable detent may also exert a frictional retention force against the fastener head.

Abstract: An anchoring device for anchoring a rod in a bone or a vertebra and for use with at least two rods having a different diameter is provided. The anchoring device includes a shaft and a head for connection to one of said rods. The head is connected to said shaft and has a recess with a base and two substantially vertically extending legs defining a channel for receiving the rod in said channel. The anchoring device further includes a fixation element for clamping said rod in said channel. The fixation element and said base each have a contact surface contacting said rod, the contact surfaces being shaped so as to be able to clamp any of the different rods.

Abstract: A fracture fixation device is described for fixing a bone having a near cortex and a far cortex, comprising a shaft portion configured to span a distance between the near cortex and the far cortex of the bone; a head portion adjoining the shaft portion and providing for engagement of the device with a bone plate, wherein the head portion is integral with the shaft portion; and a threaded front section for engagement of the device with the far cortex of the bone, wherein the device permits motion of the shaft portion relative to the near cortex.

Abstract: An extensible pedicle screw coupling device for holding a spinal rod in the head of a pedicle screw is disclosed. The device is extensible so as to fasten to the rod stably while maintaining fixing power if there is a gap between the vertebra and the rod. The device comprises pedicle screws that are inserted into the vertebrae, and a coupler in which the pedicle screw inserted into the vertebra and a head of the pedicle screw are connected, and the rod is housed therein, and fixes the rod by screw fastening the retainer to a thread formed on the top, and an extending means that can adjust the length so as to correspond to the distance between rod and vertebra is installed on the pedicle screw and the coupler.

Abstract: An extensible pedicle screw coupling device for holding a spinal rod in the head of a pedicle screw is disclosed. The device is extensible so as to fasten to the rod stably while maintaining fixing power if there is a gap between the vertebra and the rod. The device comprises pedicle screws that are inserted into the vertebrae, and a coupler in which the pedicle screw inserted into the vertebra and a head of the pedicle screw are connected, and the rod is housed therein, and fixes the rod by screw fastening the retainer to a thread formed on the top, and an extending means that can adjust the length so as to correspond to the distance between rod and vertebra is installed on the pedicle screw and the coupler.

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. A down-loadable compression insert with tool receiving arm extensions, a down-loadable friction fit split retaining ring and 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: A bone anchor system anchors a support member to a bone. The bone anchor system comprises a body having a shank adapted for insertion into a hole in the bone. A head is formed on the shank. The head has a support engagement portion adapted to secure the support member to the body. A passage extends from an entry point to an exit point formed in the body. An expandable member has a flexible wall at least partially enclosing an anchoring chamber. The expandable member has an expanded state configured to conform to a cavity in the bone. The anchoring chamber is in fluid communication with the exit point. The expandable member is adapted to expand when a filler material is provided into the anchoring chamber. A portion of the expandable member conforms to the cavity and the body and the support member are substantially anchored to the bone.

Abstract: A spinal fixation system that utilizes a composite rod to which polyaxial pedicle screw/tulip assemblies are secured, a screwdriver that permits independent threading of a guide member to the tulip and independent threading of the pedicle screw, together with interengaging conical surfaces that true the screwdriver with the pedicle screw. In preferred embodiments, the screwdriver includes an elongated drive shaft having a handle end for imparting rotation and a pedicle screw engaging end, a cylindrical guide member rotatably mounted about said drive shaft, a knob at one end of said guide member for rotating same and a threaded tulip engaging end at the other end thereof. A grip is preferably sleeved around the cylindrical drive member and is longitudinally movable between proximal and distal positions wherein its distal end uncovers and covers, respectively, the screw engaging unit.

Abstract: A semi-rigid head for a bone screw comprising includes a first rigid portion, a second rigid portion, and a semi-rigid portion. The first rigid portion is configured to receive a fixation rod. The second rigid portion is configured for coupling with a bone screw. The semi-rigid portion links the first rigid portion with the second rigid portion.

Abstract: A bone fastener includes a shaft extending from a first end to a second end and defines a longitudinal axis. The shaft includes an inner surface that defines an axially extending cavity. The bone fastener further includes a body disposed within the cavity and in fixed engagement with the inner surface. The body includes a rigid element positioned within only a subregion of the cavity to form a stiffened zone exclusively in an adjacent portion of the shaft. Methods of use are disclosed.

Abstract: A multi-axial screw assembly comprises a receiver, a base member, a crown and a bone screw. The base member includes an aperture extending through the base member and an opening on a bottom portion of the base member. The base member is rotatable relative to the receiver and has an inner wall extending partially around the aperture. The crown is received in the receiver and configured to mate to the base member. The crown has a projection configured to extend into the opening of the base member. The projection is configured to have an abutting surface. The bone screw is located between the base member and the crown, the bone screw is configured to be provisionally fixed within the receiver by a force between the abutting surface of the projection and the inner wall of the base member.

Abstract: A multi-axial screw assembly comprises a bone anchoring member, a receiver, a crown and a snap ring. The receiver member has an aperture extending along a central axis of the receiver member. The aperture receives the bone anchoring member. The receiver member has a cutout on an interior wall of the receiver member. The cutout has an angled wall surface. The angled wall surface extends along the central axis of the receiver. The crown is configured to be received within the receiver member along the central axis of the receiver member. The crown has a groove around the circumference of the crown. The snap ring is configured to be received in the groove of the crown and in the cutout in the receiver member. The snap ring exerts an axial force on the crown when the snap ring abuts the angled wall surface of the receiver member.

Abstract: The present invention relates to a screw for fixing vertebra comprising a cage as a prosthesis which can be extended to be protruded beyond an external diameter of a screw, and improving the drawback from detaching from the spine following surgical procedures.

Abstract: An orthopedic implant including a U-shaped head having a base and first and second legs extending therefrom and spaced apart from one another to define a U-shaped channel. The first and second legs each include a distal end and together define a distal opening in communication with the U-shaped channel. The first and second legs also together define an internal helical thread extending from the distal end toward the base and configured for threading engagement with a lock member. The first leg defines a starter thread turn proximately adjacent the distal end and having a thread profile substantially similar to a thread profile of primary thread turns proximal the starter thread turn. The second leg defines a non-threaded feature proximately adjacent the distal end that removes and is devoid of the starter thread turn. In one embodiment, the non-threaded feature comprises a substantially smooth and non-threaded surface extending proximally from the distal end of the second leg toward the base.

Abstract: A snap-off surgical screw configured for threading into a bone of a patient using a driver member, comprising a shaft extension joined to a screw portion via a frangible connection. The frangible connection comprises at least one defect formed through an outer surface of the frangible connection. The defect is configured to promote selective separation of the shaft extension from the screw portion at the defect. A proximal end of the screw portion is preferably provided with a recess, and the frangible connection is preferably positioned in the recess to thereby configure the shaft extension to snap-off from the screw portion below the proximal end of the screw portion.

Abstract: A receiving part for coupling a rod to a bone anchoring element includes: a receiving part body with a rod receiving portion and a head receiving portion having an open end for introducing a head of a bone anchoring element, and a locking ring, wherein the head receiving portion includes a plurality of flexible wall portions, the flexible wall portions and the locking ring being configured to engage each other at circumferentially distinct pressure areas having positions corresponding to circumferentially separated projections on at least one of the flexible wall portions or the locking ring, and wherein the locking ring exerts a first force on at least one of the flexible wall portions at a corresponding pressure area, and exerts a second force less than the first force on the at least one flexible wall portion in a region circumferentially adjacent to the corresponding pressure area.

Abstract: A bone stabilizer assembly includes a fixation element, a coupling element, and a compression nut. The fixation element is adapted to engage a bone and having a head portion and shank portion. The coupling element has an internal bore sized to receive the shank portion of the fixation element and a pyramid-shaped seat for supporting the head portion of the fixation element. The coupling element is adapted to receive a stabilizer rod. The compression nut is engagable with the coupling element and is adapted to rotatingly move distally into the coupling element to translate a force to the head portion through the rod and the saddle such that the head portion is forced against the seat of the coupling element to prevent relative movement between the fixation element and the coupling element.

Abstract: An improved system and method for positioning screws and rods to immobilize bones is provided. Specifically, the system and method is optimal for performing transforaminal lumbar interbody fusion (TLIF) and other interbody fusions in the spine. The system involves pedicle screws detachably connected to wires that guide rods down to the screws. The wires are strong, narrow, flexible, adjustable in tension, and easily disconnected from the screws after rod placement via a process such as cutting, radiating, burning, dissolving, etc. The use of wires to place the rods avoids the conventional bulky tower apparatuses of the prior art while at the same time enhancing the accuracy of placement. One of the preferred methods involves relying upon the natural lordotic curvature of the spine and the narrow diameter of the wires to insert many elements through a single minimally invasive incision.

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 durability enhanced compliant sleeve. 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 bone anchoring nail is provided having a threadless shaft with a free end, a head opposite to the free end, the head having a substantially U-shaped recess for accommodation of a rod or a rod-shaped element, a longitudinal bore extending through the shaft and opening towards any one of the head and the free end and a plurality of openings extending through the wall of the shaft and being in communication with the bore. The bone anchoring nail allows quick insertion and reliable fixation enhanced by the in-growth of blood vessels.

Abstract: A tool set for implanting a rod in a human spine in conjunction with bone screws. The tool set includes a pair of end guide tools that receive opposite ends of the rod in channels and under manipulation by a surgeon facilitate transport of the rod toward the bone screws attached to the guide tools. Intermediate guide tools having guiding pass through slots are utilized to guide intermediate locations along the rod toward associated bone screws. An attachment structure operably connects the guide tools to the bone screws. The guide tools each include a lower guide and advancement structure to allow a closure top with mating structure to be rotated and driven downward against the rod and to cooperate with similar structure in the bone screw to seat and lock the rod therein.

Abstract: A locking spring screw, comprising: a cylindrical screw body; a flexible spring member; and, a screw head attached to the cylindrical screw body, wherein the screw head comprises a tool slot adapted for receipt of the spring member, at least one outlet adjacent to the tool slot adapted for passage therethrough of a tongue of the spring member, and, a ridge located opposite the at least one outlet from the cylindrical screw body and at least partially around the circumference of the screw head.

Abstract: Disclosed is a spine fixation apparatus, more particularly, a pedicle screw implanted into a spine and an operating device for the pedicle screw capable of easily inserting a rod to a head 5 section of the pedicle screw in order to securely fix the spine. The pedicle screw has a head section including a recess part defined by first and second sidewalls, a screw section, and a support unit formed at an upper portion of the recess part of the head section while connecting the first sidewall to the second sidewall.

Abstract: A bone screw having a head portion and an adjoining shaft portion is described. The shaft portion has a front, a mid, and a neck section, where at least two of the sections having complementary features and/or attributes to facilitate positive-locking, but flexible engagement of the bone screw to a bone.

Abstract: An orthodontic mini-screw comprises a screw head arranged to be coupled to an ancillary member. A threaded body couples to the screw head and has a first portion arranged to locate in a cortical bone layer of a patient's jaw bone. A second portion of the threaded body is arranged to extend a predefined distance beyond the cortical bone layer and into an adjacent cancellous bone layer, such that a channel extends through the threaded body and out of at least one void located in the first portion. In use the channel is arranged to deliver a settable bio-compatible material into the cancellous bone layer to assist with anchorage of the mini-screw.

Abstract: The invention concerns a fixation apparatus comprising a holder (2?) and a tension sleeve (4?) receiving a bone screw (1?), wherein the bone screw (1?) has a shaft (10?) with a front thread (11?) and a head (12?) at the rear end, and the holder (3?) has a through borehole (30?) with a receiving seat (32?), in which the tension sleeve (4?) is mounted and able to swivel, while the shaft (10?) has a thickening (15?) in a rear region, to the front of the head (12?), whose width increases toward the head (12?), and the width of the tension sleeve (4?) is larger than the width of the shaft (10?) immediately before the thickening (15?) and smaller than the greatest width of the thickening (15?). When screwed in, the thickening (15) widens the tension sleeve (4?) so that it is pressed by its envelope against the wall of the receiving seat (32?). In this way, an angle-stable pressing is achieved for any given orientation of the bone screw (1?).

Abstract: A bone anchoring device has an anchoring element, a receiving portion, and a pressure element. The anchoring element includes a shank to be anchored in a bone or a vertebra and a head, the head having an exterior surface with a spherical segment-shaped portion. The shank and the head are separate parts. The receiving portion includes a first end, a second end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, and a first region adjacent to the second end for receiving a spherical segment-shaped section of the head. The pressure element exerts pressure on the head to lock the head in the receiving portion. The head has a hollow inner portion to receive a free end portion of the shank and wherein the head and the end portion are formed such that the end portion can be elastically clamped by the head.

Abstract: A cannulated bone anchor comprising a self-centering ball-joint suitable for use in a spine stabilization prosthesis which supports the spine while providing for the preservation of spinal motion. The cannulated bone anchor has a deflectable post partially received in a socket of a housing formed in the head of the bone anchor. A centering rod received partially in the post and partially within the housing operates to align the post with the longitudinal axis of the bone anchor. Deflection of the post bends the centering rod which in turn applies a restoring force upon the post. The centering rod includes an inner-superelastic core and an outer polymer sheath.

Abstract: A bone screw system is presented. The bone screw system has a fixation element, a receiving element, coupling element, and a compression element. In one aspect, the fixation element is adapted to engage a bone and has a head portion and a threaded shank portion.

Abstract: A bone anchoring device includes a bone anchoring element having a shaft for anchoring in the bone 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 first end and a second end and a U-shaped recess for receiving the rod, the recess extending from the first end in the direction of the second end thereby forming two free legs and a second portion at the side of the second end opposite to the first end 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: Systems for reducing a fracture in a bone, comprising a bone plate and a polyaxial fastener. In some examples the head of the polyaxial fastener has a deformable portion. As a fastener is inserted into an opening of a bone plate, threads located within the opening deform the deformable portion to secure the fastener in place at a desired angle within the opening. The head of the fastener also includes a bottom portion that bears against a portion of the opening to move the bone plate relative to the underlying tissue. A securing member or other structure may be included at the interface of the head and the deformable portion to secure the deformable portion to the head. At least one flute may be included on the deformable portion that provides a lead-in for the threads within the opening to cut into the deformable portion.

Abstract: Bone screws have heads which are provided with a hex socket as well as a threaded portion. A screw driver system includes a hex driver and a threaded driver. The screw driver system permits driving the screw through a plate system into a bone until desired compression is obtained. Then the screw is locked to the plate while maintaining the imparted compression.

Abstract: An apparatus and method for reinforcing a bone fixation assembly includes a first connector element for coupling to a first bone screw assembly, a second connector element for coupling to a second bone screw assembly, and an elongated connecting element that interconnects the first connector element and second connector element. An end of the first connector element is adapted to engage an elongated fixation element in a first bone screw assembly, and an end of the second connector element is adapted to engage an elongated fixation element in a second bone screw assembly.

Abstract: A retraction device comprises at least one retracting blade and a pedicle screw. The retracting blade has a distal end having at least one projection with a passage for engaging a retention pin. The pedicle screw has a threaded body and a movable head. The movable head has at least one recess with a channel that can be aligned with the passage of the projection.

Abstract: An osteosynthesis system includes a pedicular screw and a bar of longitudinal axis, the screw having a U-shaped head with two branches and a base for defining an inter-branch space in which the bar is received, a screw shank with a bone thread, and elements for blocking the bar in the space and including at least a tab and movement elements for moving the tab relative to the branches in a plane substantially parallel to the axis, the movement elements being arranged so that the tab occupies two positions, a first position where the tab does not co-operate with the bar, and a second position where the tab co-operates with at least one of the branches in such a manner that at least a portion of the tab is situated in the space and applies on the bar a pressure force that is directed towards the base of the U-shape.

Abstract: A polyaxial bone screw includes a shaft, a body member, and a toroidal member. The shaft includes a longitudinal axis and a proximal end with a head having a generally rounded surface. The body member has a bore disposed longitudinally therethrough and a groove defined by a luminal surface of the bore. The toroidal member has an elliptical cross-section with a major axis and disposed within the groove to engage the generally rounded surface of the head at a point of contact.

Abstract: A bone anchor assembly and a rigid extension rod removably coupleable thereto. The bone anchor assembly includes a screw base and a pivoting post. The post has a first recess in a proximal endface thereof, which may have first threads therein. The extension rod has a distal section separated from a proximal section by an intermediate section. The rod distal section has external threads that are threadingly engageable with the threads of the post recess. The rod third section may have external third threads of a different size. The rod intermediate section has an unthreaded exterior. When the extension rod is coupled to the post, an exterior of the second section of the extension rod is aligned with the exterior of the post. Other connection approaches may be used. An optional spacer may also be used to couple the rod to the post.

Abstract: The present invention relates to dynamic bone fixation elements and a surgical method to stabilize bone or bone fragments. The dynamic bone fixation elements preferably include a bone engaging component and a load carrier engaging component. The bone engaging component preferably includes a plurality of threads for engaging a patient's bone and a lumen. The load carrier engaging component preferably includes a head portion for engaging a load carrier (e.g., bone plate) and a shaft portion. The shaft portion preferably at least partially extends into the lumen. Preferably at least a portion of an outer surface of the shaft portion is spaced away from at least a portion of an inner surface of the lumen via a gap so that the head portion can move with respect to the bone engaging component. The distal end of the shaft portion is preferably coupled to the lumen.