Interlaminar, interspinous stabilization devices for the cervical spine

Dynamic, rigid, and convertible dynamic-to-rigid devices and methods of using such devices to treat spinal instability conditions of the cervical spine are provided. The devices may include an interspinous, interlaminar stabilization device configured for interlaminar placement between the spinous processes of adjacent cervical vertebrae and optionally secured to the lamina using bone screws or crimped or rigidly fixed to the spinous process. Multiple devices may be used to enable treatment of multiple levels at the same time.

TECHNICAL FIELD

The present disclosure relates to devices and methods for treating spine instability, in particular the cervical spine, and includes interlaminar, interspinous stabilization devices and methods of using such devices for segmental stabilization of vertebrae of the cervical spine.

BACKGROUND

Spinal instability is often attributed to undesirable excessive motion between vertebrae and can cause significant pain and neurological deficits leading to significant morbidity and mortality. The instability may result from a number of causes, including abnormalities of the vertebrae, the intervertebral discs, the facet joints, and connective tissue around the spine. These abnormalities may arise from congenital abnormalities, diseases, disorders or defects of the spine from trauma or bone degradation, such as osteoarthritis, cancer, or degenerative disc disease. When the spine becomes unstable, the vertebral column becomes misaligned and may produce micromotion between adjacent vertebrae. Vertebral misalignment and micromotion may result in wear to the vertebral bone surfaces and ultimately generate severe pain. These conditions are often chronic and create progressive problems for the sufferer.

Known treatments for spinal instability can include long-term medical management, rehabilitation strategies, interventional (needle-based) approaches, or open surgery. Medical management is generally directed at controlling the symptoms, such as pain reduction, rather than correcting the underlying problem. For some patients, this may require chronic use of pain medications, which may alter patient mental state or cause other negative side effects. Rehabilitation strategies often focus on muscle strengthening and spinal alignment. Interventional approaches may include facet, disc, and/or nerve root injections of analgesics and/or anti-inflammatory medications. Surgical treatment typically includes neural decompression with and without spinal fusion. Procedures are often designed to decompress the nerve roots and/or spinal cord as well as restore vertebral alignment and orientation, replace or repair failing components (e.g. discs), and alleviate the pain.

Recently, a variety of interspinous stabilization devices have become available. These devices are typically implanted between the spinous processes of two or more adjacent vertebrae. By stabilizing the spinous processes in this way, significant stress may be taken off the intervertebral discs to prevent disease progression or to improve conditions such as spinal or neuroforaminal stenosis. In addition, vertebral motion may be controlled without severely altering the anatomy of the spine.

These devices, along with other interspinous stabilization systems, can be secured between adjacent spinous processes using a number of different mechanisms. For example, such devices can include sharp barbs or other surface projections that engage the bony surface of a spinous process. In addition, flexible ligaments or sutures can be placed around the implants and adjacent bone. In some cases, the devices may be rigidly attached to the spinous process using a bone screw or other suitable bone anchor to prevent the interspinous device from migrating or slipping out of position.

Fusion of the spine is a well-known and widely practiced medical procedure to alleviate symptoms and potential problems related to spinal instability such as severe back and/or neck pain due to misaligned, damaged or otherwise diseased spines. In many cases, spinal fusion is carried out by removing mobile interfaces (e.g. failing discs, facet joints, bone) followed by implantation of bone material and/or fusion-promoting adjuncts. Bony fusion can be significantly promoted by decreasing micromotion within the treated segments through orthosis or bracing. External orthosis (e.g. back brace) was the primary means of reducing micromotion and promoting fusion prior to the advent of internal spinal fixation systems. These systems initially employed wires to hold spinal segments firmly together. The wiring systems evolved to more rigid, durable implants including pedicle and lateral mass screws, rods, and intervertebral cages. These rigid spinal fixation systems are often designed to maintain or restore spinal alignment and spacing while enabling bone healing and fusion.

Where it is difficult to maneuver and insert rigid implantable device(s) due to the size limitations or delicate anatomical site (i.e., closeness to facet joints, nerves or spinal cord, for example) of the area to be implanted, it is desirable to provide an implant that inserts along the midline structures and may be converted from a flexible implant into a rigid one that can promote fusion as the spinal condition evolves.

It may be desirable in some situations, such as where the spinous process is damaged, weakened, brittle or insufficient in size to serve as a bearing surface, to provide an interspinous stabilization device that can support the spinal segment independent of the failing element(s). It is further desirable to provide an interspinous stabilization system that can be configured to provide either dynamic or rigid stability to the affected vertebral segment of the spinal column. For instance, it would be desirable to provide such a system whereby the dynamic stability allows for controlled motion of the adjacent vertebrae being affected for example following posterior cervical foraminotomy. It would be even more desirable to provide the same system having the ability to allow for rigid, fusion-promoting securement if so desired or needed. Further still, it would be desirable to provide a system that can provide the option of either dynamic or rigid stability at different levels of the vertebral segment, while also allowing for multi-level vertebral stabilization.

Whereas there are a number of options for the lumbar spine, very few such options exist for the cervical spine. Due to the limited space afforded the surgeon, and the biomechanical considerations of the highly-mobile cervical spine, the much desired option of a dynamic stabilization device is rarely available. Even more desirable are convertible devices that allow the option of either dynamic or rigid fixation at the spinal segment of the cervical spine to be treated. Accordingly, it is desirable to provide dynamic, rigid, and convertible dynamic to rigid devices and methods of using such devices for interlaminar, interspinous stabilization of the cervical spine.

SUMMARY

The present disclosure provides dynamic, rigid, and convertible dynamic-to-rigid devices and methods of using such devices to treat spinal instability conditions of the cervical spine. The devices may include an interspinous, interlaminar stabilization device configured for interlaminar placement between the spinous processes of adjacent cervical vertebrae and optionally secured to the lamina using bone screws or crimped or rigidly fixed to the spinous process. Multiple devices may be used to enable treatment of multiple levels at the same time.

In one aspect of the present disclosure, interlaminar, interspinous spinal stabilization devices configured for rigid fixation are provided. These devices may comprise a unitary body having a contour suitable for placement between adjacent cervical vertebrae. In one embodiment, the unitary body may include screw holes to accommodate bone screws such as lateral mass screws. In another embodiment, the body may include brackets for receiving a spinous process of the cervical spine. These brackets may be crimped onto the spinous process. Alternatively, or in addition to the crimping, the brackets may include through-holes for receiving a rivet therethrough. In another embodiment, the body may include extended wings and/or brackets. These devices are configured for rigid fixation of the spinal segment, thereby enabling fusion at that level.

In another aspect of the present disclosure, interlaminar, interspinous spinal stabilization devices configured for dynamic fixation are provided. These devices may comprise a unitary body having a contour suitable for placement between adjacent cervical vertebrae. In one embodiment, the unitary body may include upper and lower plates connected by a flexible hinge or midsection. The unitary body may include one or more pair of brackets for receiving a spinous process of the cervical spine. These brackets may be crimped onto the spinous process. Alternatively, or in addition to the crimping, the brackets may include through-holes for receiving a rivet therethrough. In still another embodiment, the body may include straps for securing around the spinous process. These devices are configured for dynamic fixation of the spinal segment.

In still another aspect of the present disclosure, modular, two-part interlaminar, interspinous spinal stabilization devices are provided. These two-part devices are configured for conversion from a dynamic-to-rigid segmental stabilization of the cervical spine. In one embodiment, a dynamic fixation device may be provided with screw holes for fixation with bone screws. The dynamic fixation device may include an opening for receiving a complementary rigid fixation device. The rigid fixation device may act to block the dynamic fixation device, thereby hindering movement and promoting fusion. In one embodiment, the rigid fixation device may comprise one or more brackets for receiving a spinous process. These brackets may be crimped onto the spinous process. Alternatively, or in addition to the crimping, the brackets may include through-holes for receiving a rivet therethrough.

In further aspect of the present disclosure, various locking screws and mechanisms are provided for use with the devices of the present disclosure. In one embodiment, a retaining plate or locking plate may be provided for use with the devices to prevent backout of screws from the screw holes. In another embodiment, the screw may be provided with self-cutting threads to embed the screw into the screw hole during insertion, thereby preventing backout. In still another embodiment, the screw may be provided with spring tongues to embed the screw into the screw hole during insertion, thereby preventing backout.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. Additional features of the disclosure will be set forth in part in the description which follows or may be learned by practice of the disclosure.

DETAILED DESCRIPTION

FIG. 1Aillustrates an exemplary embodiment of an interlaminar, interspinous spinal stabilization device10of the present disclosure. The device10may comprise a main body12having an upper surface14, a lower surface16, an anterior portion18, and a posterior portion20. The main body12may be formed as a solid body, and as such, the upper and lower surfaces14,16and the anterior and posterior portions18,20may be interconnected, as illustrated. The main body12itself may also be shaped to conform to the anatomy of the spine, and in particular, the cervical spine2. For instance, the posterior portion20may be slightly curved, as shown, as can be the sides26of the main body12.

As further illustrated, the four corners22of the main body12at the anterior portion18can be enlarged to accommodate screw holes24. The screw holes24may be angled to allow the insertion of screws40through the holes and towards the upper or lower vertebrae4,6,8of the cervical spine2, as shown inFIGS. 2A to 2C. In one embodiment, these screws40may diverge and extend upwardly or downwardly. These screws40may be, for example, lateral mass screws and may include an elongated shaft42with a threaded tip44at one end and a screw head46at an opposite end. Such use of lateral mass screws40along with the implantable device10would enable a rigid, secure fixation of the device10in between the cervical vertebrae and consequently stabilize that vertebral segment of the spine2being treated.

The implantable devices10ofFIGS. 1A and 1Bmay be contoured to allow ease of insertion in between the vertebrae, such as for example, by providing a main body12having a wedge shape. For instance, the sides26and posterior portion20may be tapered or narrowed to provide a leading edge. Additionally, the main body12may have a low profile to allow stacking of devices10at multiple levels. This stacking is illustrated inFIGS. 2A to 2Cin which multiple devices10may be used in adjacent levels of the cervical spine2, without abutting one another or crowding the area. The contours of the main body12enable the device10to have a closely matched fit within the interspinous space of the cervical spine2. Thus, when in use, the device10provides sufficient interlaminar support of the cervical vertebrae4,6,8, as shown inFIGS. 2B and 2C. Accordingly, the device10may be appropriately considered an interspinous, interlaminar spinal stabilization device10for the cervical spine.

FIG. 1Billustrates the interlaminar, interspinous spinal stabilization device10ofFIG. 1Awith an optional retaining or locking plate50. Retaining plates, also known as locking plates,50are known in the industry for use in blocking the opening of screw holes24and the associated screw heads46within these screw holes24to prevent undesired screw backout, or the loosening of the screws out of the device10, over time and with repeated micromotion. As shown inFIG. 1B, an exemplary embodiment of a locking plate50may be provided along with the interlaminar, interspinous spinal stabilization device10ofFIG. 1A. The locking plate50may have a similar, complementary shape as the anterior portion of device10, with a narrowed midsection flanked by enlarged arms52. The plate50may include a screw hole54for insertion of a fixation screw (not shown) into a receiving hole32in the anterior portion18of the device10, to securely lock the locking plate50onto the main body12. Once fixed to the main body12, the locking plate50should rest firmly against the anterior portion, while the arms52should cover or block at least a portion of the screw holes24and screw heads46.

FIGS. 3A and 3Billustrate another exemplary embodiment of an interspinous, interlaminar spinal stabilization device110of the present disclosure, whileFIGS. 4A and 4Billustrate the device110in situ in a cervical spine2. The device110ofFIGS. 3A and 3Bshare similar features to the device10ofFIGS. 1A and 1B. As such, these similar features are designated by the same reference number following the prefix “1”. Like device10, device110may comprise a main body112having an upper surface114, a lower surface116, an anterior portion118, and a posterior portion120. The main body112may be formed as a solid body, and as such, the upper and lower surfaces114,116and the anterior and posterior portions118,120may be interconnected, as illustrated. The main body112may also be shaped to conform to the anatomy of the spine, and in particular, the cervical spine2. For instance, the posterior portion120may be slightly curved, as can be the sides126of the main body112. Such curvature enables the form-fitting adherence of the device110to the anatomical region of the intervertebral space of the cervical spine2, as previously described above.

Also like device10, the two corners122of the main body112at the anterior portion118can be enlarged to accommodate screw holes124. The screw holes124may be angled to allow the insertion of screws40such as those previously described through the holes and towards the upper or lower vertebrae4,6,8of the cervical spine2, as shown inFIGS. 4A and 4B. In one embodiment, these screws40may diverge and extend upwardly or downwardly. Use of the screws40would enable a rigid, secure fixation of the device110in between the cervical vertebrae and consequently stabilize that vertebral segment of the spine2.

In addition, device110may further include a surface modification such as a protrusion or fin128on the upper surface114of the main body112, as illustrated. This protrusion or fin128may further enhance stabilization and anchorage within the interspinous space. In addition, device110may be configured to have a pair of brackets134extending from the lower surface116of the main body112. These brackets134may collectively form a stirrup, or bone-receiving region136. As illustrated inFIGS. 4A and 4B, these brackets134allow the device110to receive a spinous process of the lower vertebra. The brackets134may be configured to be malleable, and allow crimping onto the spinous process. Teeth, spikes, barbs, ridges, or other similarly sharp bone-piercing protrusions or surface roughening features138may be provided on the brackets134to further enhance bone contact with the spinous process.

Like device10above, the interlaminar, interspinous spinal stabilization device110ofFIGS. 3A and 3Bmay utilize one or two different types of fixation mechanisms: screw fixation, such as for example with lateral mass screws40, may be utilized for securing the device110to the upper vertebra, while crimping to the spinous process of the lower vertebra may also be utilized. The device110is configured such that either one or both mechanisms may be implemented, without affecting the other mechanism. And similar to device10, the present device110also allows stacking or multiple devices110to be used at one time at different levels of the cervical spine2.FIGS. 4A and 4Billustrate the use of the devices110whereby one level utilizes screw fixation while the other level utilizes crimping.

Turning now toFIGS. 5A, 5B, 6, 7A, 7B, 8A, 8B, 9A, and 9B, the present disclosure also provides exemplary embodiments of interlaminar, interspinous spinal stabilization devices200that are flexible and allow some motion of the cervical vertebrae while simultaneously stabilizing the vertebral level.FIGS. 5A and 5Billustrate one such exemplary embodiment. Device200as shown inFIGS. 5A and 5Bmay comprise an upper plate202and a lower plate204connected by a flexible midsection206, allowing the plates202,204to move relative to one another. The plates202,204create an open free end208, as illustrated. The device200may be configured to nest securely in between the cervical vertebrae, as illustrated inFIGS. 7A and 7B.

Due to the unique anatomy of the cervical spine2, the upper plate202may be shorter in length than the lower plate204, as can be seen inFIGS. 5B and 7B. In addition, the plates202,204may also be contoured, or curved, in order to matingly fit and interlaminarly support the cervical vertebra at that level. The upper plate202may further include a surface modification such as a protrusion or fin228, as illustrated. This protrusion or fin228may further enhance stabilization and anchorage within the interspinous space, similar to previously described protrusion or fin128above.

Brackets214may be provided on the upper and lower plates202,204. Each pair of brackets214may create a stirrup, or bone-receiving area216, for receiving a spinous process, as can be seen inFIG. 7A. The brackets214may be malleable, to allow crimping onto the spinous process, as previously described with bracket134of device110. Additionally, brackets214may include teeth, spikes, barbs, ridges, or other similarly sharp bone-piercing protrusions or surface roughening features218to further enhance bone contact with the spinous process. These brackets214may be angled relative to the upper and lower surfaces202,204, as illustrated inFIGS. 5B and 7B, in order to conform to the unique anatomy of the cervical spine, and allow stacking or multi-level stabilization, as shown inFIGS. 7A and 7B.

FIG. 6illustrates another exemplary embodiment in which interspinous, interlaminar spinal stabilization device200may optionally utilize a fixation element through the brackets214. As shown, the device200of the present disclosure may be provided with through-holes226at each of the brackets214for receiving a rivet230therethrough. As used herein, it is to be understood that the term rivet is intended to broadly encompass a nut and bolt assembly, without limitation. The rivet230may comprise a threaded bolt232that threadingly engages a threaded nut240at threaded end234. Either one or both of the pair of brackets214of the device200may utilize this additional fixation mechanism.

It is contemplated that the user may elect to crimp the brackets first214, then place the rivet230through the brackets214to secure them onto the spinous process, or merely use the rivet230without first crimping, as the rivet230would effectively move the brackets214together in a crimping manner during installation. Furthermore, the user has the option of utilizing crimping and/or rivet installation in either one or both of the pair of brackets214. Accordingly, it is possible to crimp at the upper level, and use a rivet230at the lower level, or vice versa, without affecting the stability of the device200. Such flexibility enables the user to customize the level of rigidity, fixation, and flexibility of the device at a single level. For example, while not shown, it is contemplated that any one or more of the devices200ofFIGS. 7A and 7Bmay also include a rivet230through the pair of brackets214of the upper or the lower plates202,204, as desired.

FIGS. 8A and 8Billustrate yet another exemplary embodiment of the interspinous, interlaminar spinal stabilization device200′ of the present disclosure. The device200′ shares all of the same features of device200ofFIGS. 5A and 5B, with the exception that, in this embodiment, the brackets214are replaced with bars244. These bars244may include a slot246for receiving a fastening element such as a tie, belt, or strap250, such as illustrated. The straps250may be configured to securely wrap around the upper or lower spinous processes of the level of the cervical spine being stabilized. As shown, the straps250may be connected to a housing unit260that allows length-wise adjustment by a mechanism such as a rotating knob or dial262. In one embodiment, the adjustment mechanism may comprise a screw that, when rotated, tightens the straps250around the spinous process. This housing unit260may be located at the side of the device200′. Use of the strap250would thus enable fixation without the need to drill a hole through the spinous process.FIGS. 9A and 9Billustrate the use of this embodiment in situ, at a single level. Of course, it is contemplated that multiple devices200′ may be stacked and therefore multiple levels may be stabilized at the same time, as previously described.

FIGS. 10A and 10Billustrate even still another exemplary embodiment of the interspinous, interlaminar spinal stabilization device300of the present disclosure. The device300may comprise a main body302having two different pairs of extensions for attachment to bone: a pair of wings or arms304that extend upwardly from the main body302, and a pair of brackets314extending downwardly from the main body302. Each of these extensions will be described in greater detail now.

As shown, wings or arms304may extend from the main body302in an upwardly direction. The ends of the wings or arms304may include screw holes306for receiving a bone screw such as, for example, the lateral mass screws40previously described. The screw holes306may be angled to allow the screws40to be inserted into the body of the vertebra of the upper level where stabilization is taking place.

A pair of brackets314may extend downwardly from the main body302to create a stirrup or bone-receiving area316for receiving a spinous process. The brackets314may further include teeth, barbs, spikes, ridges, or other similarly sharp bone-piercing protrusions or surface roughening features318to further enhance bone contact with the spinous process. These brackets314may be angled relative to the main body302, in order to conform to the unique anatomy of the cervical spine, and allow stacking or multi-level stabilization, as previously described and shown. Also similar to the devices previously described, the brackets314may optionally utilize a fixation element through the brackets314. As shown, the device300of the present disclosure may be provided with through-holes326at each of the brackets314for receiving a rivet230therethrough. The rivet230may comprise a threaded bolt232that threadingly engages a threaded nut240, similar to the rivet230previously described.

The main body302may further include a central opening310which may be used to hold a fusion enhancing material or therapeutic agent, such as for example, bone substitute material, bone morphogenic protein, bone graft material including demineralized bone matrix, bone chips, autograft, allograft, xenograft, medical agents, stem cells, proteins, or other biological agents that promote bone fusion or provide therapeutic benefits, including antibiotics or antimicrobial agents and the like. The main body302may additionally include a surface modification such as a protrusion or fin328, as illustrated. This protrusion or fin328may further enhance stabilization and anchorage within the interspinous space, similar to previously described protrusion or fin128,228above.

FIGS. 11A and 11Bshow a variation of device300′ in which all of the features of device300are present, along with an additional pair of brackets314. As illustrated, the device300′ provides yet an additional extension comprising an upwardly extending pair of brackets314. The upwardly extending pair of brackets314is identical to those extending downwardly, and are angled and shaped to match the anatomy of the cervical spine2.FIG. 11Bshows the device300′ in use with a rivet230through the upwardly extending brackets314. It is understood, of course, that the rivet230may be utilized by the lower brackets314, or both upper and lower brackets314, with optional lateral mass screws40extending through the wings304. At the same time, the user may optionally crimp the brackets314in addition to, or instead of, using the rivet230. Accordingly, this type of unitary body302provides several different rigid fixation options at different locations, thereby promoting fusion.

FIGS. 12A, 12B, 13A, 13B, 14, 15A, 15B, and 16A-16Dshow various exemplary embodiments of a modular, two-part interspinous spinal stabilization device of the present disclosure. Turning now toFIGS. 12A and 12B, a two-part modular design for an interlaminar, interspinous spinal stabilization device400is illustrated. The device400may comprise a main frame402having a sleeve-receiving opening410for receiving a sleeve or insert450. The main frame402may further include upwardly extending arms or wings404, similar to the wings or arms304previously described above. The wings or arms404may include angled screw holes406similar to the screw holes306previously described above.

Within the main frame402is an insert or sleeve450comprising a main body452. A pair of brackets454extends upwardly from the main body452, while another pair of brackets454extends downwardly from the main body452in a fashion similar to that shown inFIGS. 11A and 11Bof device300′. Like device300′, the pair of brackets454creates a stirrup or bone-receiving area456for receiving a spinous process. The brackets454may further include teeth, spikes, barbs, ridges, or other similarly sharp bone-piercing protrusions or surface roughening features458to further enhance bone contact with the spinous process. These brackets454may be angled relative to the main body452, in order to conform to the unique anatomy of the cervical spine, and allow stacking or multi-level stabilization, as previously described and shown. Also similar to the devices previously described, the brackets454may optionally utilize a fixation element through the brackets454. Accordingly, the brackets454may be provided with through-holes464for receiving a rivet230therethrough. The rivet230may comprise a threaded bolt232that threadingly engages a threaded nut240, similar to the rivet230previously described.

The main body452may further include a central opening460which may be used to hold a bone graft or other fusion enhancing material. The main body452may additionally include a surface modification such as a protrusion or fin462, as illustrated. This protrusion or fin462may further enhance stabilization and anchorage within the interspinous space, similar to previously described protrusion or fin128,228,328above.

Although not shown, it is contemplated that bone screws such as, for example, lateral mass screws40may be used to fix the wings404of the main frame402to a vertebra. Optional rivets230may be used for fixing either or both of the pair of brackets454to a spinous process. Additionally, each of the pair of brackets may be configured to be crimped onto the spinous process, either instead of, or in addition to, the use of the rivets for rigid fixation.

In one embodiment, the two components of the device400may comprise different materials for different properties. For example, the main frame402may be formed of a polyetheretherketone (PEEK) material to facilitate fixation with lateral mass screws40, while the sleeve or insert450may be formed of a metal such as, for example, titanium to allow optional crimping and/or fixation with a rivet230.

FIGS. 13A and 13Billustrate still another exemplary embodiment of a two-part modular interlaminar, interspinous spinal stabilization device500. The device500shares similar features to device400previously described, and may comprise a main frame502having an insert-receiving slot510for receiving an insert550. The main frame502may further include upwardly extending arms or wings504, similar to the wings or arms304,404previously described above. The wings or arms504may include angled screw holes506similar to the screw holes306,406previously described above for use with a bone screw such as, for example, the lateral mass screws40previously described. However, unlike the opening410of device400, the insert-receiving slot510of device500is partially open and contains a rail512for sliding engagement with the insert550, as shown by the arrow inFIG. 13A.

The insert550may comprise a main body552, and a pair of brackets554extending downwardly from the main body552in a fashion similar to that shown inFIGS. 11A and 11Bof device300′. Like device300′, the pair of brackets554creates a stirrup or bone-receiving area556for receiving a spinous process. The brackets554may further include teeth, spikes, barbs, ridges, or other similarly sharp bone-piercing protrusions or surface roughening features558to further enhance bone contact with the spinous process. These brackets554may be angled relative to the main body552, in order to conform to the unique anatomy of the cervical spine, and allow stacking or multi-level stabilization, as previously described and shown. Also similar to the devices previously described, the brackets554may optionally utilize a fixation element through the brackets554. Accordingly, the brackets554may be provided with through-holes564for receiving a rivet230therethrough. The rivet230may comprise a threaded bolt232that threadingly engages a threaded nut240, similar to the rivet230previously described.

The main body552may further include a central opening560which may be used to hold a fusion enhancing material or therapeutic agent such as described above. The main body552may additionally include a surface modification such as a protrusion or fin562, as illustrated. This protrusion or fin562may further enhance stabilization and anchorage within the interspinous space, similar to previously described protrusion or fin128,228,328,462above. In addition, the main body552may include a groove566that allows the body552to be slidingly inserted into the insert-receiving opening510of the main frame502along the rails512.FIG. 13Bshows a fully assembled device500in which the insert550is nested securely within the frame502of device500.

Although not shown, it is contemplated that bone screws such as, for example, lateral mass screws40may be used to fix the wings504of the main frame502to a vertebra. Optional rivet230may be used for fixing the pair of brackets554to a spinous process. Additionally, the pair of brackets may be configured to be crimped onto the spinous process, either instead of, or in addition to, the use of the rivet for rigid fixation.

As previously described for device400, the two components of the device500may comprise different materials for different properties. For example, the main frame502may be formed of a polyetheretherketone (PEEK) material to facilitate fixation with lateral mass screws40, while the insert550may be formed of a metal such as, for example, titanium to allow optional crimping and/or fixation with a rivet230.

The main frame502as well as the insert550may be provided in various other forms to provide ultimate flexibility regarding the amount of fixation to bone that can be provided. For instance,FIG. 14shows the main frame502of device500but with the option of an insert550′ instead of insert550. Insert550′ is similar to insert550, but has the added feature of a second pair of brackets554. The brackets554may have the features of bracket554of insert550.

As shown inFIGS. 15A and 15B, it is possible to utilize insert550′ with the upper and lower brackets554along with frame502at one level, while utilizing insert550with a single pair of lower brackets554with frame502at an adjacent level. Thus, as illustrated, it is possible to stack multiple devices500by interchanging the components of the modular device500in order to create an ideal configuration that matches the anatomy of the cervical spine and allows multi-level stabilization without crowding.

FIGS. 16A-16Dshow another variation of device500in which the main frame502′ now includes two pairs of arms504,508. The upper arms504and lower arms508are similar in feature, and can contain screw holes506for receiving a bone screw such as, for example, the lateral mass screws40previously described. These arms504,508may further be positioned adjacent to one another so as not to add unnecessary bulk to the overall frame502′. The insert-receiving slot510of the frame502′ may still contain a rail512for mating with the groove566of the insert550,550′, and as such, the mechanism of attaching the insert550,550′ to the frame502′ remains the same as described above, and as illustrated inFIGS. 16C and 16D.

In the embodiments ofFIGS. 12A, 12B, 13A, 13B, 14, 15A, 15B, and16A-16D, these modular, two-part interlaminar, interspinous spinal stabilization devices enable an initially dynamic device to be converted into a fusion-enabling device by inserting the insert or sleeve into the dynamic device. The insert or sleeve thus acts to block the dynamic device from movement, thereby allowing subsequent fusion treatment of the spinal segment.

FIGS. 17A and 17Bshow an exemplary embodiment of a locking screw600of the present disclosure. The locking screw600may comprise a threaded shaft602that extends into a leading tip604at one end and a screw head606at the opposite end. The tip604may be self-tapping or self-leading. The screw head606may include a tool-engaging opening608. In addition, the screw600may comprise self-cutting threads610adjacent the screw head606, as shown. The self-cutting threads610enable the screw600to embed itself upon insertion into a PEEK screw hole506, such as the one for main frame502of device500, as illustrated inFIG. 17B. Such a screw600would be useful for any number of devices of the present disclosure.

FIGS. 18A and 18Bshow another exemplary embodiment of a locking screw of the present disclosure. The locking screw700may comprise a threaded shaft702that extends into a leading tip704at one end and a screw head706at the opposite end. The tip704may be self-tapping or self-leading. The screw head706may include a tool-engaging opening708. In addition, the screw700may comprise spring tongues710adjacent the screw head706, as shown. The spring tongues710enable the screw700to lodge itself upon insertion into a PEEK screw hole506, such as the one for main frame502of device500, as illustrated inFIG. 18B. Such a screw700would be useful for any number of devices of the present disclosure.

It is contemplated that the devices described and shown herein are useful for treatment of persistent neck pain and joint stress, such as that experienced following disc replacement surgery. Furthermore, the implant devices and their components may be linked together by fastening elements like screws (including overlapping screws), wire bands, ties, and the like, in order to provide an interconnected construct of multiple devices at multiple levels. Additionally, in some instances, small openings may be provided in the midline aspect of the devices provided herein to allow optional suturing of midline structures (e.g., muscle, fascia) during reconstruction of the soft tissues overlying the region.

It is understood that the devices of the present disclosure may be formed from a number of biocompatible materials, including the materials previously mentioned. For instance, the devices may be formed of a medical grade metal like titanium or a titanium alloy. The devices may also be formed from a variety of other materials, such as stainless steel, cobalt chrome, ceramics, and/or polymeric materials, such as ultra-high molecular-weight polyethylene (UHMWPE) and polyetheretherketone (PEEK), either alone or in combination with other suitable materials.