Abstract: A spinal jack adapted for installation between first and second vertebral processes and includes a three dimensional and arcuate ergonomic main body constructed from a first and second portions, from which is displaceable an upper body between each of retracted and expanded positions. Each of the jack halves includes gripping portions adapted for engaging the vertebral processes. A worm gear mechanism includes a central horizontally arrayed and rotatable worm gear supported within the main body and accessible through an inlet aperture. A tool bit is engageable with a bit receiving location of the worm gear which is accessible through the inlet aperture.

Abstract: An adjustable spinal stabilization system for maintaining preselected spacing and movement between adjacent vertebrae in a spinal column and for providing overall stability thereto. The system includes at least one interlaminar member positioned in the spaces intermediate a first vertebra and the vertebrae positioned immediately above or immediately below and adjacent to the first vertebra. The interlaminar member is operatively connected to an adjustable support structure and cooperates therewith to maintain the preselected spacing between adjacent vertebrae and to provide overall stability to the spinal column.

Abstract: A modular spinal fixation system for securing an elongate rod to a bone of a patient includes a plurality of bone anchors, each having a universal shank head and an anchor portion opposite the universal shank head configured for fixation to the bone. The system further includes a plurality of pivoting and non-pivoting receiver sub-assemblies, with each receiver sub-assembly including a receiver having an upper portion defining a channel configured to receive the elongate rod and a base defining a lower portion of a central bore communicating with a bottom surface of the receiver through a bottom opening, and one of a shank head-engaging retainer or a rod-engaging insert positioned within the central bore.

Abstract: An interspinous process device includes a first plate, a second plate, and a transverse member between the first plate and the second plate, wherein the second plate is adjustably coupled to the transverse member. A post is coupled to the transverse member and a spring mechanism is disposed between the post and the first plate. The spring mechanism is configured to provide a preloaded compression force to the first and second plates. Methods of implanting the interspinous process device using an inserter tool are also disclosed.

Abstract: Interspinous process implants are disclosed. Also disclosed are systems and kits including such implants, methods of inserting such implants, and methods of alleviating pain or discomfort associated with the spinal column.

Abstract: A pivotal bone anchor assembly includes a bone anchor having a capture portion and an anchor portion opposite the capture portion, and a receiver assembly in a pre-assembled configuration that includes a receiver, a retainer, and a pressure insert. The receiver has a central bore configured to receive the capture portion through a bottom opening, with a lower portion of the central bore including a narrower engagement portion adjacent the bottom opening and a wider expansion portion above the narrower engagement portion. The pre-assembled retainer is configured to widen within the wider expansion portion to receive the capture portion of the bone anchor during its uploading through the bottom opening, then to close around and secure the capture portion while providing for pivotal motion of the bone anchor relative to the receiver.

Abstract: A patient-specific navigation guide for use in spinal surgery including a first and a second guide member, both integral with a supporting frame and extending along a respective longitudinal development axis from a proximal opening to a distal opening for guiding surgical instruments on a first vertebra of a patient. The guide also includes contact members designed to match with a corresponding plurality of contact areas on a first and on a second vertebra of the patient to define a single coupling configuration of the patient-specific navigation guide on the patient's vertebrae. The first and second guide members are substantially opposite with respect to a median plane orthogonal to a straight line joining the longitudinal axes of the first and second guide members. The navigation guide also comprises a single additional third guide member that is integral with the frame and is adapted to abut on a second vertebra.

Abstract: Methods and apparatus provide for: (i) coupling a spinous process plate to one lateral side of a spinous process of a spine of a patient, the spinous process plate extending substantially parallel to a sagittal plane (anterior-posterior plane) through the spine of the patient, the spinous process plate including a first fixation element facilitating a connection of the spinous process plate to the one lateral side of the spinous process; (ii) coupling a laminar plate to a laminar on the one lateral side of the spinous process of the spine, the laminar plate extending transversely from the spinous process plate and transversely to both the sagittal plane and a coronal plane (lateral plane) through the spine of the patient, the laminar plate including a second fixation element facilitating a connection of the laminar plate to the laminar on the one lateral side of the spinous process; (iii) engaging a sub-laminar hook to the laminar on the one lateral side of the spinous process, the sub-laminar hook extending

Abstract: Devices and methods for positioning and immobilizing at least two adjacent vertebrae using adjacent spinous processes. The method includes positioning a spinous process fusion device in an interspinous space between adjacent spinous processes including a rod and a first wing, and attaching a second wing to the rod, for example, using a ratcheting mechanism.

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

Abstract: An interspinous stabilization device configured to fit interlaminarly between adjacent vertebrae and their spinous processes, while also cooperating with a bone graft, or bone substitute, component to facilitate fusion at that segment of the spine is disclosed. Also provided is a method for using such a device and bone graft, or bone substitute, component to stabilize a spinal segment.

Abstract: The present invention discloses spinous process fixation devices, systems, and instruments. The spinous process fixation device includes a first member, a second member, a third member, and a fourth member. Each of the first and second members includes a body and an engagement member and the engagement member of the first member couples to the engagement portion of the second member. Each of the third and fourth members also includes a body and an engagement member and the engagement member of the third member couples to the engagement portion of the fourth member. A method of assembling the spinous process fixation device and methods of using the spinous process fixation devices are also disclosed. A reamer instrument is also disclosed.

Abstract: Systems, devices, and methods for treating the spine are disclosed herein. Medical devices can be positioned along a subject's spine to treat various conditions and diseases. The medical device can include an actuator assembly and a clamp assembly. The actuator assembly can be positioned at an interspinous space between a superior spinous process and an inferior spinous process. The actuator assembly can be used to reconfigure the clamp assembly such that the clamp assembly clamps onto the superior and inferior spinous processes.

Abstract: Interspinous process implants are disclosed. Also disclosed are systems and kits including such implants, methods of inserting such implants, and methods of alleviating pain or discomfort associated with the spinal column.

Abstract: Presently disclosed is a spinal implant. In an embodiment, a spinal implant includes a porous body configured to promote bone growth. The porous body may have an attachment portion that is configured to secure the spinal implant to a fixation system attached to one or more vertebra. The porous body may also include a fusion plate extending from the attachment portion and configured to contact transverse processes, lamina, or facet of adjacent vertebrae. Accordingly, when the attachment portion is secured to the fixation system, the fusion plate may be maintained in compression against the transverse processes, lamina, or facet.

Abstract: The present disclosure relates to an interspinous omnidirectional dynamic stabilization device, including a first fixing part, a second fixing part, a connecting structure and an elastic structure. The first fixing part and the second fixing part are fixedly connected to each other through the connecting structure and elastic structure. The bottoms of the first fixing part and the second fixing part are provided with one or more barbs. The elastic structure is made up of one or more U-shaped structures connected to each other. The first fixing part and the second fixing part are provided with fixing holes respectively.

Abstract: Provided herein is a spinal graft that fuses to and stabilizes the spine upon placement thereby helping to prevent spinal stenosis recurrence and eliminating pain associated with an unstable spine. The graft may be coated with a human birth tissue composition. Also provided herein are methods of stabilizing the spine after decompression surgery.

Abstract: An implantable spacer for placement between adjacent spinous processes in a spinal motion segment is provided. The spacer includes a body defining a longitudinal passageway. A first arm and a second arm are connected to the body. Each arm has a pair of extensions and a saddle defining a receiving portion configured for seating a spinous process of a scoliotic spine or a spine with misaligned spinous processes. Each arm has a proximal caming surface and is capable of rotation with respect to the body. An actuator assembly is disposed inside the longitudinal passageway and connected to the body. When advanced, a threaded shaft of the actuator assembly contacts the caming surfaces of arms to rotate them from an undeployed configuration to a deployed configuration. In the deployed configuration, the distracted adjacent spinous processes are seated in the superior and inferior arms of the spacer.

Abstract: A resilient core is positioned between bony projections which are offset from a principal load bearing region of a spinal joint. Shaped projections extend from the core, and engage the bony projections by conforming to anatomical landmarks, and may be fastened to the bony projections. During flexion of the joint, the core absorbs some of the force of compression, and limits an extent to which the joint may compress. If the shaped projections are connected to the bony projections, extension of the joint is inhibited by the projections and the core, limiting the extent to which the joint may be distracted. In this manner, healing is fostered, and a weakened or damaged joint is protected from excessive movement.

Abstract: A spinal stabilization system and method are provided for treating a patient's spinal column, for maintaining preselected spacing and movement between adjacent vertebrae in a spinal column, and for providing overall stability thereto. The system includes an interlaminar member positioned in the space intermediate a first vertebra and the vertebrae positioned immediately below and adjacent to the first vertebra. The interlaminar member is operatively connected to an adjustable support structure and cooperates therewith to maintain the preselected spacing between adjacent vertebrae and to provide overall stability to the spinal column.

Abstract: A spinal screw assembly providing an adjustable securement of a fixation rod across at least two vertebrae. The assembly includes a pedicle screw having a spherical head portion, a threaded shaft portion and a tool engagement surface in the head portion for use in driving the screw into a vertebrae. The head portion of the screw is positioned in a body member adjacent a curvilinear surface disposed about an aperture in the end of the body member such that the shaft portion of the screw extends therethrough and the curvilinear inner surface abuts and mates with the head portion of the screw so as to define a ball joint therewith. The body member additionally defines a pair of opposed parallel slots therein adapted to receive a portion of the fixation rod and a locking cap bears against the fixation rod to releasably secure the rod within the assembly.

Abstract: A spinal screw assembly providing an adjustable securement of a fixation rod across at least two vertebrae. The assembly includes a pedicle screw having a spherical head portion, a threaded shaft portion and a tool engagement surface in the head portion for use in driving the screw into a vertebrae. The head portion of the screw is positioned in a body member adjacent a curvilinear surface disposed about an aperture in the end of the body member such that the shaft portion of the screw extends therethrough and the curvilinear inner surface abuts and mates with the head portion of the screw so as to define a ball joint therewith. The body member additionally defines a pair of opposed parallel slots therein adapted to receive a portion of the fixation rod and a locking cap bears against the fixation rod to releasably secure the rod within the assembly.

Abstract: A spinal screw assembly providing an adjustable securement of a fixation rod across at least two vertebrae. The assembly includes a pedicle screw having a spherical head portion, a threaded shaft portion and a tool engagement surface in the head portion for use in driving the screw into a vertebrae. The head portion of the screw is positioned in a body member adjacent a curvilinear surface disposed about an aperture in the end of the body member such that the shaft portion of the screw extends therethrough and the curvilinear inner surface abuts and mates with the head portion of the screw so as to define a ball joint therewith. The body member additionally defines a pair of opposed parallel slots therein adapted to receive a portion of the fixation rod and a locking cap bears against the fixation rod to releasably secure the rod within the assembly.

Abstract: An expandable interspinous process fixation system capable of restoring spinal stability and facilitating fusion. In one embodiment, the expandable interspinous process fixation system includes a central ramp, a first endplate, and a second endplate, the central ramp capable of being moved in a first direction to move the first and second endplates outwardly and into an expanded configuration. Each endplate supporting fixed and/or adjustable spinous process engaging plates.

Abstract: A spinal implant apparatus that is an expandable spacer including features to minimize or eliminate spacer cant or offset during and after completing the expansion process. The spacer includes a top component, a base component in engagement with the top component, and an expansion mechanism arranged to change the top component's position with respect to the base component. The mechanism for causing expansion may be a screw, a cam, a wedge or other form of distracting device. In one embodiment, the expandable spacer includes a base component with a set of towers and a top component with a set of corresponding silos, where the towers and silos are configured to minimize or eliminate tilt of the top component as it extends upwardly from the base component.

Abstract: The invention refers to a device 1 for supporting a spinal column in the region of the transverse or spinous processions of two adjacent vertebrae and/or for spreading two adjacent ribs, comprising at least a first body 2 and a second body 3, each body having a receptacle 4 for a transverse or spinous process of a vertebra or for a rib; and a rotational joint 12 between the first body 2 and the second body 3, such that the first body 2 and the second body 3 are rotatable relative to one another about a common axis of rotation X, wherein the distance between the receptacles of the first body 2 and the second body 3 can be adjusted by means of the rotational movement of the first body 2 relative to the second body 3, which is characterized in that the receptacles 4 of the first body 2 and the second body 3 are designed such that the transverse or spinous processes of adjacent vertebrae or adjacent ribs can be received therein at least in a rotational angle of 0° to 180°, preferably 0° to 270°, of the first body

Abstract: Systems, methods and devices for providing orthopedic implant augments are provided which have fastener locking mechanisms. The augments include a surface for mating with an implant component and a surface for interfacing with a patient's bone. The fastener locking mechanisms are aligned such that the augment may be locked in a variety of orientations while maintaining close contact with both an implant and a patient's bone. The alignment of the locking mechanisms provides variability and adjustability to the augment to address a variety of bone anatomies and requirements.

Abstract: A spinal screw assembly providing an adjustable securement of a fixation rod across at least two vertebrae. The assembly includes a pedicle screw having a spherical head portion, a threaded shaft portion and a tool engagement surface in the head portion for use in driving the screw into a vertebrae. The head portion of the screw is positioned in a body member adjacent a curvilinear surface disposed about an aperture in the end of the body member such that the shaft portion of the screw extends therethrough and the curvilinear inner surface abuts and mates with the head portion of the screw so as to define a ball joint therewith. The body member additionally defines a pair of opposed parallel slots therein adapted to receive a portion of the fixation rod and a locking cap bears against the fixation rod to releasably secure the rod within the assembly.

Abstract: Devices, systems and methods for dynamically stabilizing the spine are provided. The devices include an expandable spacer having an undeployed configuration and a deployed configuration, wherein the spacer has axial and radial dimensions for positioning between the spinous processes of adjacent vertebrae. The systems include one or more spacers and a mechanical actuation means for delivering and deploying the spacer. The methods involve the implantation of one or more spacers within the interspinous space.

Abstract: A device for treatment of spondylotic disease includes a distractor for distracting vertebral facets of first and second vertebrae located adjacent each other. The distractor includes a first abutment surface for interfacing with an inferior articular facet of the first vertebra. The distractor also includes a second abutment surface for interfacing with the superior articular facet of the second vertebra corresponding to the inferior articular facet of the first vertebra. The first and second abutment surfaces of the distractor engage with each other and are separated by a predetermined distance.

Abstract: In some embodiments, a method includes disposing a flexible band through an aperture of a support member, the support member having a fixation portion configured to secure the support member to a first bone portion. The method includes advancing a portion of the flexible band through an attachment portion of the flexible band until the flexible band is secured to a second bone portion. The method includes advancing a portion of the fixation portion of the support member into the first bone portion until the support member is secured to the first bone portion.

Abstract: This equipment (1) comprises at least one connecting bar (100), at least one flexible ligament (101) and at least one connecting assembly (1). According to the invention, —a connecting part (2) of said assembly forms an engagement conduit (15) for engagement of the connecting bar (100); —the body (6) of this part (2) has a central conduit (10) for receiving a tightening part (3) and two lateral conduits (11) for receiving the strands of the ligament; —said tightening part (3) comprises a threaded pin (16) capable to be engaged into said central conduit (10) and a base (17) for bearing against the connecting bar (100); —the nut (4) has a distal portion (31) coaxial with itself, on which is pivotally mounted a pressing ring (5) adapted to be engaged into said lateral conduits (11) and to tighten the strand of the ligament (101).

Abstract: Implantable devices are provided for stabilizing adjacent vertebrae and the lumbosacral region of a patient. The devices can comprise an interspinous flexible spacer body having a substantially U-shape comprising a superior section, inferior section, and a midsection extending therebetween. The superior and/or inferior sections can include a pair of lateral walls configured to engage a spinous process of a vertebra. Fixation caps can be provided for securing a spinous process of a vertebra to the flexible spacer body. To secure the flexible spacer body between the lumbar vertebra and an adjacent vertebra, an anchor assembly is provided. Also provided are methods of using the implantable devices to stabilize a patient's spine.

Abstract: This invention relates to an improved structure for an interspinous stabilization device that more evenly distributes loads throughout the adjacent vertebrae than known interspinous stabilization devices, and further readily compensates for graft settling so as to maintain continued axial loading of the graft. More specifically, this invention relates to a medical device that helps in performing a spinal fusion procedure by holding the bone graft in place and stabilizing the facet screw by a plate that is attached to it. The invention also performs a dynamic function that compensates for settling of the bone graft over time. This dynamic function may, if desired, be enhanced by a movement-limiting mechanism that allows extension but not flexion such that the bone graft fusion remains in contact and fusion takes place.

Abstract: The present invention relates to an interspinous dynamic implant. Provided is an interspinous dynamic implant comprising: an upper plate which adheres to an upper spinous process; a lower plate which adheres to a lower spinous process; a movable part, coupled between the front portion of the upper plate and the front portion of the lower plate, for enabling the upper plate and the lower plate to move upwards, downwards, left and right within a certain range according to the movement of spinous processes; an upper spinous process coupling means for tightly coupling the upper plate to the upper spinous process; and a lower spinous process coupling means for tightly coupling the lower plate to the lower spinous process.

Abstract: Prosthetic replacement for a posterior element of a vertebra comprising portions that replace the natural lamina and the four natural facets. The prosthetic replacement may also include portions that replace one or more of the natural spinous process and the two natural transverse processes. If desired, the prosthesis replacement may also replace the natural pedicles. A method for replacing a posterior element of a vertebra is also provided.

Abstract: The present disclosure provides an intervertebral cage including superior and inferior members each including an engagement surface for engaging a corresponding vertebrae. The intervertebral cage also includes a posterior member that extends between a posterior end of the superior and inferior members and spaces them from each other in a superior-inferior direction. The superior and inferior members extend in a posterior-to-anterior direction from the posterior member and define anterior free ends to form a substantially open anterior end between the superior member and the inferior member in a posterior-anterior direction. The engagement surfaces of the superior and inferior members substantially diverge from each other in the superior-inferior direction along the posterior-to-anterior direction. The superior and inferior members each include first apertures extending therethrough in the superior-inferior direction that define a pathway through the intervertebral cage in the superior-inferior direction.

Abstract: This equipment comprises an iliac rod (2), a connection assembly (3, 4) for connecting that iliac rod to a vertebral bar, an iliac anchoring member and an iliac part connecting the iliac rod to that iliac anchoring member; said connecting assembly (3, 4) is independent of the iliac rod (2) and comprises two portions, namely: —a first portion (3), for connecting to said vertebral bar (50), that forms a closed conduit (10) for engagement of that portion (3) on that bar (50); and —a second portion (4), for connecting to said iliac rod (2), that forms a conduit (12) for the engagement of that second portion (4) on the iliac rod (2).

Abstract: Systems, devices, and methods for treating the spine are disclosed herein. Medical devices can be positioned along a subject's spine to treat various conditions and diseases. The medical device can include an actuator assembly and a clamp assembly. The actuator assembly can be positioned at an interspinous space between a superior spinous process and an inferior spinous process. The actuator assembly can be used to reconfigure the clamp assembly such that the clamp assembly clamps onto the superior and inferior spinous processes.

Abstract: An implantable spacer for placement between adjacent spinous processes in a spinal motion segment is provided. The spacer includes a body defining a longitudinal axis and passageway. A first arm and a second arm are connected to the body. Each arm has a pair of extensions and a saddle defining a U-shaped configuration for seating a spinous process therein. Each arm has a proximal caming surface and is capable of rotation with respect to the body. An actuator assembly is disposed inside the passageway and connected to the body. When advanced, a threaded shaft of the actuator assembly contacts the caming surfaces of arms to rotate them from an undeployed configuration to a deployed configuration. In the deployed configuration, the distracted adjacent spinous processes are seated in the U-shaped portion of the arms.

Abstract: Provided herein is a spinal graft that fuses to and stabilizes the spine upon placement thereby helping to prevent spinal stenosis recurrence and eliminating pain associated with an unstable spine. The graft may be coated with a human birth tissue composition. Also provided herein are methods of stabilizing the spine after decompression surgery.

Abstract: An intervertebral implant frame that is configured to be attached to a spacer body can include a pair of arms that extend longitudinally from a support member such that the arms extend substantially around the spacer body. The arms may be configured to expand, crimp, or otherwise engage the spacer body to thereby hold the spacer body to the frame. The spacer body may be made from bone graft.

Abstract: An adjustable implant (10, 60, 70, 80, 90) has a base (12) and a displaceable element (16) providing opposing tissue contact surfaces (14, 18). A linkage (20, 26) is pivotally connected to the displaceable element. A linkage mover (38, 40), engaged so as to be displaceable along the base, is associated with the linkage (20, 26) so as to define a displaceable pivot location (24, 30) for pivotal motion of the linkage relative to the base, in certain preferred embodiments, the base (12) has an internally threaded track (42, 44) in which a threaded segment of the linkage mover (38, 40) is engaged, so that rotation of the threaded segment about its central axis advances the linkage mover along the threaded track, thereby displacing the displaceable pivot locations and adjusting a separation between the first contact surface and at least part of the second contact surface.

Abstract: The present invention provides spinous process implant and associated methods. In one aspect of the invention the implant limits the maximum spacing between the spinous processes. In another aspect of the invention, a spacer has at least one transverse opening to facilitate tissue in-growth. In another aspect of the invention, an implant includes a spacer and separate extensions engageable with the spacer. The spacer is provided in a variety of lengths and superior to inferior surface spacings. In another aspect of the invention, an implant includes a spacer and a cerclage element offset from the midline of the spacer in use so that the spacer defines a fulcrum and the cerclage element is operative to impart a moment to the vertebrae about the spacer. In another aspect of the invention, instrumentation for inserting the implant is provided. In other aspects of the invention, methods for treating spine disease are provided.

Abstract: An implantable device may be provided. The implantable device may comprise an upper assembly comprising a ramped base and a pair of opposing windows. The pair of opposing windows may extend upward from either lateral side of the ramped base. A gripping assembly may be disposed in each window. The implantable device may further comprise a lower assembly comprising a ramped base and a pair of opposing windows. The pair of opposing windows may extend down from either lateral side of the ramped base. A gripping assembly is disposed in each window. The implantable device may further comprise a ramped actuator assembly disposed between the upper assembly and the lower assembly. The ramped actuator may be configured to transition the implantable device from a collapsed form having a first height to an expanded form having a second height and wherein the second height is greater than the first height.

Abstract: Embodiments herein are generally directed to spinal implants for use in orthopedic stabilization assemblies. In some embodiments, these implants may be used in conjunction with laminoplasty or laminectomy procedures.

Abstract: An expandable spinal prosthesis is disclosed, including a first surface having a first plurality of tissue anchors; a second surface opposite the first surface, the second surface having a second plurality of tissue anchors; a first wall between the first and second surfaces, and a second wall between the first and second surfaces, the second wall located opposite the first wall and being movable with respect to the first wall. A surgical instrument is also provided, including an elongated shaft defining a proximal end and a distal end; a first prosthesis engagement element accessible from the proximal end and extending from the distal end; and a second prosthesis engagement element accessible from the proximal end and extending from the distal end, the second prosthesis engagement element including a plurality of gear teeth.

Abstract: Devices and methods are adapted to permit fixation and stabilization of the bony elements of the skeleton. The devices permit adjustment and maintenance of the spatial relationship between neighboring bones. The motion between adjacent skeletal segments may be maintained, limited or completely eliminated.

Abstract: Prosthetic replacement for a posterior element of a vertebra comprising portions that replace the natural lamina and the four natural facets. The prosthetic replacement may also include portions that replace one or more of the natural spinous process and the two natural transverse processes. If desired, the prosthesis replacement may also replace the natural pedicles. A method for replacing a posterior element of a vertebra is also provided.

Abstract: A polyaxial interspinous fusion device is described. The polyaxial interspinous fusion device has a fixed anchor, a polyaxial anchor, and a bone spacer. The fixed anchor has a center ring, one or more fixed anchor arms projecting laterally from the center ring, and a barrel projecting transversely from the center ring. The polyaxial anchor has a socket ring and one or more polyaxial anchor arms projecting laterally from the socket ring, wherein the socket ring has a concave engagement surface. The bone spacer has a spacer head having a convex socket engagement surface that matches the concave engagement surface of the socket ring. The bone spacer also has one or more zip lock flanges extending transversely from the spacer head and one or more bone abutments extending transversely from the spacer head. The zip lock flanges and bone abutments of the bone spacer fit through the socket ring and the barrel of the fixed anchor fits through the socket ring.