Abstract: Implementations described herein may include a system for manipulating implants coupled by a cord. The system may include a tensioner and a counter tensioner. The tensioner may include a nose assembly and a cord lock assembly for applying tension to the cord. The nose assembly may include a piston having a lumen extending therethrough for receiving the cord and a spring positionable in contact with an indicator region of the piston. The counter may be releasably coupleable to a head of an implant at a proximal end thereof and may guide the cord to a port proximate the distal end thereof, the port for receiving the nose assembly. The counter tensioner may enable translation of the implant relative to another implant implanted in an adjacent or nearby vertebrae. The indicator region of the piston may be visible through a window in a tensioner main body and may indicate cord tension when the nose assembly of the tensioner is coupled to the port of the counter tensioner and engaged with the cord.

Abstract: A receiver assembly includes a receiver with a base defining a central bore for receiving the head of a bone anchor and upright arms defining a channel for receiving a rod, with the central bore having through apertures extending outwardly to outer side surfaces of the receiver and the upright arms having top surfaces, opposite front and back surfaces, vertical tool-engaging slots extending downward from the top surfaces to the through apertures for slidably receiving an insert compression tool, and horizontal tool-engaging grooves on either side of the vertical slots that extend laterally to a front or back surface of the upright arm. The assembly also includes an insert positionable within the central bore with an upward-facing outer engagement surface located within a through aperture and aligned with a vertical tool-engaging slot, and which is configured for compressive engagement by the insert compressing tool to independently lock a position of the receiver with respect to the bone anchor.

Abstract: Methods and systems for monitoring a rod reduction process is provided. The methods and systems include determining, based on at least one parameter, a threshold for forces exerted by a tool on a rod or a pedicle screw and receiving data corresponding to a magnitude of the forces exerted by the tool on the pedicle screw or the rod during reduction of the rod into a head of the pedicle screw. A surgical plan may be updated when the monitored magnitude meets the threshold.

Abstract: A coupling assembly for coupling a rod to a bone anchoring element includes a receiving part having a first end, a second end, a recess having a bottom for receiving the rod, and an accommodation space having an opening at the second end of the receiving part for accommodating a head of the bone anchoring element, and a retainer element configured to be inserted into the receiving part from the first end and to hold at least part of the head, the retainer element having a first portion and a spring portion compressible in an axial direction attached to the first portion. When the retainer element is in the accommodation space in a first position, the spring portion extends in the axial direction from the first portion of the retainer element to an axial position between the first end of the receiving part and the bottom of the recess.

Abstract: A medical implant assembly includes a shank having a head and an anchor portion, and a receiver having a central bore with a locking recess adjacent a bottom opening, an expansion recess above the locking recess, and a horizontal ridge extending circumferentially above the expansion recess. The assembly also includes an insert uploadable into a first position within the central bore with outer surfaces engageable with the horizontal ridge in a first position, a locking ring initially positionable within the lower locking recess or the upper expansion recess, and a blocking ring positionable within the central bore at least partially above the locking ring. The locking ring is first expanded within the expansion recess during uploading the shank head through the bottom opening, and then moves downward into the locking recess to capture the shank head within the central bore.

Abstract: Systems, devices, and associated methods for correcting spinal column deformities that help minimize a number of attachment anchors utilized for correction, facilitate use of straight or contoured rods, and/or help promote a more natural, physiologic motion of the spinal column.

Abstract: A bone anchor assembly includes a shank having a head and an anchor portion, and a receiver having a first channel to receive a rod and an axial bore with an upper internal thread, interference abutment surfaces below the upper internal thread, and a bottom opening. The assembly also includes an insert having a second channel to receive the rod and opposite lateral protrusions positioned above the interference abutment surfaces upon loading into a first position within the axial bore. The assembly further includes a resiliently expandable retainer positionable within the axial bore adjacent the bottom opening to capture and hold the head in the receiver.

Abstract: A slotted washer configured to secure a K-wire to a native bone, including: an upper arm with a screw hole; a lower arm with a screw hole; a connector connecting the upper arm with the lower arm; and a K-wire opening between the connector, lower arm, and upper arm configured to receive and compress the K-wire.

Abstract: A device is configured to provide a large visible area and work area in the body of a patient for access to the interior of a body. The device has at least one outer part having an outer tube. An inner tube passes into the outer tube through this outer tube having at an outer tube distal end an expanding part which is expandable beyond the outer diameter of the outer tube.

Abstract: A pivotal bone anchor assembly includes a receiver with a base defining an internal cavity with a seating surface adjacent a bottom opening and an upper portion defining a channel configured to receive an elongate rod. The assembly also includes an anchor member having a proximal end portion with a partial spherical or spheroid shaped head to establish pivotable motion between the anchor member and the receiver, and a planar top surface surrounding an internal drive socket. The assembly further includes an insert positionable within the channel to transfer a downwardly-directed force onto the proximal end portion to lock a position of the anchor member relative to the receiver, with the planar top surface remaining spaced apart from the insert so as to not directly receive the downwardly-directed force therefrom. A method of use is disclosed.

Abstract: A favored angle screw assembly and a rod receiver body for a favored angle pedicle screw assembly. The favored angle screw assembly includes a pedicle screw and the rod receiver body. The rod receiver body includes a tubular wall having a first end with a first opening, a second end with a second opening, and a bore extending from the first opening to the second opening. The bore features a first bore section adjacent to the first opening, a second bore section adjacent the second opening, and a third bore section having a first end adjacent to the first bore section and a second end adjacent to the seat surface. The third bore section defines a transition surface that conforms to a side wall of an oblique three-dimensional shape.

Abstract: One or more connectors insertable into a surgical incision to couple rods together. The connector may include one or more bushings or joints to displace the one or more rods in one or more directions to a variety of orientations. One or more fasteners and/or bushings may be used to engage the one or more rods.

Abstract: A receiver assembly includes a receiver with upright arms extending upward from a base to define an open channel for receiving a rod, and a central bore communicating with a bottom of the base through a bottom opening and having a discontinuous guide and advancement structure proximate the tops of the upright arms. Each upright arm further includes one or more tool engagement grooves extending horizontally and circumferentially below the top of the upright arm to a front or back outer face the receiver.

Abstract: A system for percutaneous spinal fusion may include two spaced apart blades connected together by a coupling such that the blades define a percutaneous pathway from a skin incision to an implanted pedicle fastener. The coupling may be c-shaped and may have at least one flexible tab for engaging one or more holes along the length of the blades. If one of the blades becomes disconnected from the pedicle fastener, a supplemental access device may be provided comprising a tubular body having a channel therein for receiving the other of the blades. If both of the blades become disconnected, a supplemental access device may be provided comprising a gripping member received within a locking member. The gripping member may have two legs engageable with the pedicle fastener, and the locking member may move along the gripping member to prevent the legs from disengaging the pedicle fastener.

Abstract: A spinal construct includes a coupling member including a first mating surface engageable with an existing fastener implant. The existing fastener implant defines a cavity configured for disposal of an existing spinal rod implant. A connector is engageable with the existing fastener implant and has a rod extending therefrom. A locking member is engageable with a second mating surface of the coupling member. Systems, surgical instruments, implants and methods are disclosed.

Abstract: The preferred embodiment of the present invention is generally described as a lordotic pre-sacral rod implant, or implant construct, for use in association with spinal fusion procedures. In an embodiment, the lordotic pre-sacral rod implant incorporates a washer configured to press against the endplate of the L5 vertebral body and thereby force the vertebral bodies of the lumbosacral junction into a lordotic orientation.

Abstract: An articulated fixation device is provided having a high degree of adjustability for securing a plate member thereof to a skull and at least one spinal rod thereof to a vertebral bone. In one form, an adjustable bridge member is provided that is adjustably connected to both the plate member and the spinal rod. The adjustable connections can include an upper and rearward pivot connection between the plate member and the bridge member and a lower and forward pivot connection between the spinal rod and the bridge member.

Abstract: A system, a method, and instruments for manipulating a surgical cord into spinal implants to assist in correcting a spinal deformity are described. The system may include a tensioner, a tensioner extension, and a counter tensioner. One of the instruments can include an elongate body, a dual coupler, and a nose member. The elongate body has a flexible cylindrical member adapted to carry tension along a longitudinal axis, where the flexible cylindrical member is sized to receive a surgical cord through a lumen within the flexible cylindrical member. The dual coupler is disposed on a proximal end of the elongate body, and include a bore for receiving a nose portion of a tensioner and for guiding the surgical cord into the tensioner. The nose member is disposed on a distal end of the elongate body, and be adapted to discharge the surgical cord from the elongate body.

Abstract: A spinal fixation device includes an inner housing, an outer housing, a screw, and a pivot inhibitor. The outer housing is circumferentially disposed around at least a portion of the inner housing, wherein the outer and inner housings are translatable relative to one another to cause transitioning of the spinal fixation device between a locked configuration and an unlocked configuration. The screw including a screw head pivotably coupled to a lower portion of the inner housing and a shaft extending from the screw head. The pivot inhibitor is coupled to one of the inner housing or screw, such that pivoting of the inner housing about the screw head is inhibited in a direction of the pivot inhibitor.

Abstract: One or more tethers for use with fastener assemblies and a method for use of the one or more tethers with the fastener assemblies is provided. The one or more tethers can be attached between a first fastener assembly positioned with respect to a first vertebrae adjacent a first side of a spinous process of a second vertebrae and a second fastener assembly positioned with respect to the vertebrae adjacent a second side of the spinous process of the second vertebrae. The one or more tethers can be tensioned against the spinous process of the second vertebrae to mitigate stresses on an uninstrumented level of the spine.

Abstract: An occipital plate and hinged rod assembly. The occipital plate having a screw-attachment section having through holes for securing the occipital plate to a skull, a laterally-extending section, a tulip connector, a slide clip disposed underneath the laterally-extending section and engaging a base of the tulip connector, and an insert ring encompassing side walls of tulip connector. The laterally-extending section, the tulip connector, the slide clip, and the insert ring have respective surfaces with complementary curvatures that fit together. The hinged rod assembly is connected to the occipital plate by rods.

Abstract: An anchoring system for implanting in bone, the system comprising a first coupling assembly having a first clamp and a first coupling body that receives and holds a first stabilization element; a second coupling assembly that receives and holds a second stabilization element; and a plate that attaches to the first coupling assembly and the second coupling assembly, wherein the first coupling assembly attaches to a bone fastener, and wherein the first coupling body includes a cap retainer that receives a locking cap that applies a directional force to force the first coupling body toward the plate, and applies another directional force to force the first clamp toward the plate, thereby fixedly securing the first coupling body and the first clamp to the plate.

Abstract: A bone fixation system with variable z-axis translation is provided. The system includes an outer tulip coupled to a bone fastener via a screw retainer. An inner tulip is coupled to the outer tulip such that the inner tulip is longitudinally movably relative to the outer tulip. The inner tulip includes a lock that provides a seat for a connecting rod. The inner tulip together with a seated rod is permitted to translate along the z-axis inside the outer tulip when in an unlocked position. Also in the unlocked position, the bone fastener is free to angulate relative to the outer tulip. The z-axis position of the inner tulip and rod relative to the outer tulip is fixed in a locked position. Also, in the locked position, the bone fastener is locked with respect to the outer tulip. The system may be adjusted between the locked and unlocked positions by way of a set screw.

Abstract: A pivotal bone anchor assembly includes a receiver having a first channel configured to receive an elongate rod and an axial bore with a bottom opening, and a shank having a head portion positionable into the axial bore with the shank extending downward through the bottom opening. The assembly also includes an insert positionable into the axial bore above the head portion and having a second channel alignable with the first channel, opposite extensions extending outwardly in the direction of the channels to block rotation between the receiver and the insert, and upward-facing surfaces located radially outward from a central opening. The upward-facing surfaces are configured for releasable compressive engagement by a compressing tool after the elongate rod is received within the channels and prior to a final locking of the assembly with a closure top, so as to provisionally lock the shank from pivoting with respect to the receiver.

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, a down-loadable friction fit split retaining ring having inner and outer tangs 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 polyaxial bone anchoring device includes a receiving part configured to be pivotably connected to a head of an anchoring element, the receiving part having a channel for receiving a rod and an accommodation space having an opening for accommodating the head, and a sleeve-like insert piece having a sleeve axis and a spherical segment-shaped outer surface portion. The insert piece is configured to be positioned around a portion of the head in the receiving part and to pivot in the receiving part, and includes a first part and a separable second part configured to be connected with the first part by a connection structure configured to permit translational movement between the first part and the second part in a direction transverse to the sleeve axis, while preventing movement between the first part and the second part in a direction parallel to the sleeve axis.

Abstract: A modular uniplanar pedicle screw assembly for use with a polyaxial bone fastener. The modular assembly comprises a uniplanar tulip assembly adapted to be coupled to a head of the polyaxial bone fastener, wherein the uniplanar tulip assembly includes a longitudinal slot. The modular assembly further includes an adapter having a lower portion and an upper portion. The lower portion is sized and shaped to be received in a recess of the bone fastener head. The upper portion extends from the lower portion and is adapted to slide along the longitudinal slot of the uniplanar tulip assembly to allow movement of the uniplanar tulip assembly in a first plane along a direction that is parallel to a longitudinal axis of the longitudinal slot, the longitudinal slot preventing movement of the uniplanar tulip assembly in a second plane lateral to the first plane relative to the bone fastener.

Abstract: Multi-function driver instruments and related methods are disclosed herein, e.g., for applying a fastener to a bone anchor. In some embodiments, a single instrument can include features for driving multiple different types of fasteners, independently driving multiple different components of a single fastener assembly, and so forth, with the instrument being switchable between multiple operating modes to select the feature needed for a particular function. The instrument can include features for retaining a fastener to the instrument, e.g., during initial insertion of the fastener.

Abstract: The present invention relates generally to medical devices and methods generally aimed at spinal surgery. In particular, the disclosed system and associated methods relate to performing spinal fixation with the use of a deformity system.

Abstract: The present invention relates to a bone-fixation anchor comprising a rigid expandable part and a soft part. The rigid expandable part secures the anchor with respect to the bone and the soft part enables the anchor to fit any bone screw on the market.

Abstract: The present invention is directed an anchor assembly for use in spinal fixation to interconnect a longitudinal spinal rod with a patient's vertebra. The anchor assembly preferably includes a bone anchor, a body with a rod-receiving channel, an insert member (preferably a bushing), and a locking cap with a saddle. The anchor assembly preferably enables in-situ assembly where the bone anchor may be secured to the patient's vertebra prior to being received within the body of the bone anchor assembly. Accordingly, the anchor assembly enables a surgeon to implant the bone anchor without the body to maximize visibility and access around the anchoring site. Once the bone anchor has been secured to the patient's vertebra, the body may be snapped onto the bone anchor and a spinal rod may be inserted into the rod-receiving channel.

Abstract: A cam lock mechanism for use with an associated consumer product includes a base member defining a receptacle. A cam member is received in the receptacle of the base member. The cam member has an engaged position wherein the cam member is configured to be non-movably fixed relative to the associated consumer product and a released position wherein the cam member is configured to be movable relative to the associated consumer product. A lever is hingedly connected to the cam member. The lever has a closed position wherein the lever is configured to move the cam member into the engaged position and an opened position wherein the cam member is in the released position.

Abstract: A polyaxial bone screw for attaching a rod to a vertebra comprises a fastener having a threaded shank and a head. A yoke has a rod receiving channel for receiving the rod. A screw support rotatably attached to the yoke has a cavity articulatingly and rotatably supporting the fastener head, a hole receiving the threaded fastener shank therethrough, and a plurality of slots for maximum screw angulation. A crown has an upper rod receiving surface, a lower surface in contact with the fastener head and a projecting surface in contact with the yoke. A biasing element between the screw support and the yoke applies biasing forces among the fastener, the crown, and the yoke to provide sufficient friction to retain the yoke in a manipulable position relative to the fastener. A set screw is supported by the yoke to overcome the bias and to rigidly secure the components.

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, a down-loadable friction fit split retaining ring having inner and outer tangs 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 spine fixation device including an elongated bone screw partially embedded in a vertebra of a spine and a retaining head that can receive a rod and a head of the bone screw. The retaining head has an inner member that includes a screw head receiving section for receiving the screw head. The retaining head further has an outer member that includes an inner face that can contact an outer face of the screw head receiving section. When the inner face is in contact with the outer face, the screw head receiving section applies pressure to the screw head to fixate the relative angle between the bone screw and the retaining head.

Abstract: A top-loading pedicle screw system for correcting a misalignment of the spinal column of a patient. The top-loading pedicle screw assembly comprises a screw having a threaded shaft for affixation the assembly to a vertebral pedicle. The screw has a shank top forming an internal curved socket. A head is positioned within the socket to move in a multi-axial relationship thereto. A through bore is formed in the head to receive a rod that joins two or more pedicle screw assemblies to the spinal column of a patient. A locking element is inserted into the head to lock the rod to the head while also locking the head to the shank top of the screw.

Abstract: An orthopedic implant system is disclosed for use in correcting or reducing the progression of scoliosis. The orthopedic implant system can be inserted laterally or posteriorly and comprises an elongated flexible member secured to a user's spinal column via a plurality of vertebral body screws. Typically, the height of the elongated flexible member is significantly greater than the width, creating a flattened cross-sectional aspect. The vertebral body screws comprise a screw base and a screw head with a slot sized to accept an insert. Typically, the elongated flexible member is positioned within the slot via the insert, and is allowed to slide within the screw head as needed, as the user moves. However, at the apex of the user's scoliosis curve, the elongated flexible member is fixed within a vertebral body screw head.

Abstract: A polyaxial bone anchoring device includes a receiving part configured to be pivotably connected to a head of an anchoring element, the receiving part having a channel for receiving a rod and an accommodation space having an opening for accommodating the head, and a sleeve-like insert piece having a sleeve axis and a spherical segment-shaped outer surface portion. The insert piece is configured to be positioned around a portion of the head in the receiving part and to pivot in the receiving part, and includes a first part and a separable second part configured to be connected with the first part by a connection structure configured to permit translational movement between the first part and the second part in a direction transverse to the sleeve axis, while preventing movement between the first part and the second part in a direction parallel to the sleeve axis.

Abstract: Orthopedic fixation devices and methods of installing the same. The orthopedic fixation device may include a coupling element and a bone fastener, whereby the bone fastener can be loaded into the coupling element through the bottom of a bore in the coupling element.

Abstract: The present invention relates to a brace installation instrument placement that is mounted to anchors secured in an animal subject. The installation instrument includes anchor extensions coupled to the anchors. The instrument is movable with respect to the anchors to position a brace in a position more proximate the anchors. The brace can be indexed for insertion at a predetermined orientation with respect to the installation instrument. Methods and techniques for using the installation instrument are also provided.

Abstract: A clamp for a linkage for linking first and second bone fasteners of a prosthesis assembly, the clamp comprising a clamp body having a first receiving portion for receiving a first component of a prosthesis assembly and a second receiving portion for receiving a second component of the prosthesis assembly, the clamp having a deflectable member which deflects from a first position to a second position when one of the first and second components is introduced to its corresponding receiving portion, wherein when the deflectable member is in the second position and the other one of the first and second components is received by the clamp, the deflectable member is engageable with said other one of the first and second components.

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 uniplanar bone anchor system for a fixation procedure is provided. The system can include a bone fastener including a head with a bearing surface and a shaft adapted to engage an anatomy. The system can also include a saddle, which can include a first bore formed about a longitudinal axis that receives the bone fastener and a coupling bore defined transverse to the longitudinal axis. The system can also include a coupling system, which can have a second bearing surface. The coupling system can be received through the coupling bore such that the second bearing surface of the coupling system can contact the bearing surface to permit the bone fastener to move in only one plane.

Abstract: A polyaxial pedicle screw includes a screwed shaft section for anchoring the pedicle screw in a vertebra, on one axial end of which a shaft head is configured which is coupled in a rotating and/or pivoting manner as well as in a tensile-force transmitting manner to a receiving sleeve for a longitudinal support. The receiving sleeve has a fastening means for selective positional fastening of the receiving sleeve with respect to the shaft section, the fastening means at least consisting of an inlay/pin mounted in the receiving sleeve and acting on the shaft head, and a locking element acting on the inlay/pin. The inlay/pin is configured with attachment points or engagement elements, which are not covered or overlapped by the locking element, for the provisional introduction of a compressive force on the inlay/pin parallel to the locking element.

Abstract: The present invention relates to a brace installation instrument placement that is mounted to anchors secured in an animal subject. The installation instrument includes anchor extensions coupled to the anchors. The instrument is movable with respect to the anchors to position a brace in a position more proximate the anchors. The brace can be indexed for insertion at a predetermined orientation with respect to the installation instrument. Methods and techniques for using the installation instrument are also provided.

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, a down-loadable friction fit split retaining ring having inner and outer tangs 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 fastener includes a proximal member having an inner surface that defines an implant cavity and an outer surface including a first threaded portion configured for penetrating fixation with tissue and a second portion. The proximal member defines a longitudinal axis. An intermediate member includes an inner surface extending between a proximal portion connected with the second portion and a distal portion. A distal member includes an outer surface extending between a proximal portion disposed with the distal portion of the intermediate member and a distal portion configured for penetrating fixation with tissue. The distal member is configured for axial translation relative to the intermediate member. Methods of use are disclosed.

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 uniplanar bone anchor system for a fixation procedure is provided. The system can include a bone fastener including a head with a bearing surface and a shaft adapted to engage an anatomy. The system can also include a saddle, which can include a first bore formed about a longitudinal axis that receives the bone fastener and a coupling bore defined transverse to the longitudinal axis. The system can also include a coupling system, which can have a second bearing surface. The coupling system can be received through the coupling bore such that the second bearing surface of the coupling system can contact the bearing surface to permit the bone fastener to move in only one plane.

Abstract: A pedicle screw fixation system and method for use of the same are disclosed. In one embodiment, a tulip is provided for holding a head of a pedicle screw substantially along a longitudinal axis. The tulip includes opposing first and second U-shaped receiving slots aligned along a transverse axis. A rod is received by the opposing first and second U-shaped receiving slots. A coupling collar includes a plurality of resilient fingers circumferentially disposed therearound such that a snap fit engagement with the head of the pedicle screw formed. The coupling collar includes a first deformable face operable for contact with the rod. A set screw is for adapted for driving engagement through the tulip along the longitudinal axis such that a second deformable face is positioned for contact with the rod. The first and second deformable faces conform to the shape of the rod in response to forceful engagement therewith.

Abstract: The present invention relates generally to a surgical device for the correction of deformities of the spinal column and finds particular, although not exclusive, utility in devices which are surgically implantable. Presently known implantable surgical devices are unable to provide for the progressive correction of spinal deformities assisted by active movements of the human body without fusion of the involved part of the spinal column. The present surgical device comprises a spinal column straightening means for permitting the relative rotation of two substantially adjacent vertebrae about a common axis substantially only in opposite rotational directions.

Abstract: A bone screw of minimally invasive fixation device for lumbar comprises a positioning casing and a screw body. The positioning casing includes a rod securing base and an alignment portion, both of which are integrally formed; an annular notch is formed between them. The alignment portion has at least two pairs of rod alignment openings in a bulb-shaped or keyhole-shaped form with an upper portion larger than a lower portion. Two longitudinal notches extend from near the top across the alignment openings to the rod securing base. The screw body includes a spherical head and a screw rod; the outer diameter of the spherical head is larger than that of the screw rod. The screw body is rotatably connected to the bottom portion of the positioning casing; the spherical head of the screw body is arranged in the spherical pit of the rod securing base.