Locking mechanism

A spinal implant includes a locking mechanism. The locking mechanism includes an inner surface defining a tapered passageway. A tapered collet is configured for disposal in the tapered passageway. The tapered collet has an inner surface defining a passageway configured for disposal of a longitudinal member. The tapered collet is configured to translate within the tapered passageway between a non-locking orientation in which the longitudinal member is moveable relative to the tapered collet and a locking orientation in which the longitudinal member is fixed relative to the tapered collet.

TECHNICAL FIELD

The present disclosure generally relates to medical devices for the treatment of musculoskeletal disorders, and more particularly to a locking mechanism used during treatment of a spine disorder.

BACKGROUND

Spinal pathologies and disorders such as scoliosis and other curvature abnormalities, kyphosis, degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, tumor, and fracture may result from factors including trauma, disease and degenerative conditions caused by injury and aging. Spinal disorders typically result in symptoms including deformity, pain, nerve damage, and partial or complete loss of mobility.

Non-surgical treatments, such as medication, rehabilitation and exercise can be effective, however, may fail to relieve the symptoms associated with these disorders. Surgical treatment of these spinal disorders includes correction, fusion, fixation, discectomy, laminectomy and implantable prosthetics. Correction treatments used for positioning and alignment may employ implants, such as fixation devices, for stabilization of a treated section of a spine. This disclosure describes an improvement over these prior art technologies.

SUMMARY

Accordingly, a spinal implant is provided. In one embodiment, in accordance with the principles of the present disclosure, the spinal implant includes a locking mechanism. The locking mechanism includes an inner surface defining a tapered passageway. A tapered collet is configured for disposal in the tapered passageway. The tapered collet has an inner surface defining a passageway configured for disposal of a longitudinal member. The tapered collet is configured to axially translate within the tapered passageway between a non-locking orientation such that the longitudinal member is axially moveable within the passageway of the tapered collet and a locking orientation such that the longitudinal member is fixed relative to the tapered collet.

In one embodiment, in accordance with the principles of the present disclosure, the locking mechanism includes an outer member including an inner surface defining a first passageway. The first passageway defines a first central axis along its length. An inner member is engaged to the inner surface of the outer member and defines a second central axis along its length. The inner member includes an inner surface defining a second passageway configured for disposal of a longitudinal member. The second passageway defines a third central axis along its length offset from the second central axis. The locking mechanism is configured to rotate between a non-locking orientation in which the first and third central axes are co-axial such that the longitudinal member is movable relative to the inner and outer members and a locking orientation in which the first and third central axes are offset such that the longitudinal member is fixed relative to the inner and outer members.

In one embodiment, in accordance with the principles of the present disclosure, the locking mechanism includes a wall having an inner surface defining an arcuately shaped first passageway. An outer member is disposable with the inner surface of the wall. The outer member includes an inner surface defining an arcuately shaped second passageway having a first central axis along its length. An inner member extends between a proximal end and a distal end disposable within the second passageway. The inner member defines a second central axis along its length. The inner member includes an inner surface defining a third passageway extending between the proximal and distal ends configured for disposal of a longitudinal member. The third passageway defines a third central axis along its length offset from the second central axis. The locking mechanism is configured to rotate between a non-locking orientation in which the first and third central axes are co-axial and the longitudinal member is movable relative to the inner and outer members and a locking orientation in which the first axis is offset from the third axis and the longitudinal member is fixed relative to the inner and outer members.

While multiple embodiments are disclosed, still other embodiments of the present application will become apparent to those skilled in the art from the following detailed description, which is to be read in connection with the accompanying drawings. As will be apparent, the present disclosure is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present disclosure. Accordingly, the detailed description is to be regarded as illustrative in nature and not restrictive.

Like reference numerals indicate similar parts throughout the figures.

DETAILED DESCRIPTION

The exemplary embodiments of the surgical system and related methods of use disclosed are discussed in terms of medical devices for the treatment of musculoskeletal disorders and more particularly, in terms of a spinal implant including a locking mechanism for locking a spinal implant. It is envisioned that the spinal implant may be employed in applications such as correction of deformities such as kyphosis, scoliosis. For example, the spinal implant can include an interspinous process plate fixation device incorporating a locking mechanism.

In one embodiment, a locking mechanism is provided for locking a longitudinal member, such as, for example, a spinal rod, post or screw relative to a surface, such as, for example, a spinal plate. The locking mechanism includes a tapered lock that creates an interference fit between an inside taper of a plate and a tapered collet. The tapered collet possesses a snap feature that will resist engagement of the locking taper and allow translation of the plate until a force is applied to the tapered collet to release the snap. The applied force to engage the tapered collet with the inside taper of the plate can occur by an instrument or the plate and collet can possess threads where a nut can create the applied force for locking the locking mechanism.

In one embodiment, a locking mechanism includes a tapered lock with a spherical collar that can be pressed into position so as to create an interference fit between an inside taper of the spherical collar and a tapered collet. The tapered collet possesses a snap feature that will resist engagement of the locking taper and allow translation of a plate until a force is applied to the tapered collet to release the snap. The applied force to engage the tapered collet with the inside taper of the spherical collar can occur by an instrument or the spherical collar and collet can possess threads where a nut can create the applied force to lock the locking mechanism. This locking feature can restrict translation and orbital motion of the plate. In one embodiment, the spherical collar is slit such that the spherical feature will expand and cause an interference fit between the outside of the sphere and the inside of the plate as the tapered collet is pressed into the inside of the sphere's inside taper. In one embodiment, the spherical collar does not have a slit to retain orbital motion after translational motion is restricted.

In one embodiment, a locking mechanism includes an off center axis locking nut that can be threaded to a position which will align inside hole features between an inside cylinder and an outside cylinder. Twisting of the outside cylinder will rotate the axis of the outside cylinder to create an interference fit between both cylinders and a post or screw. The outside cylinder may or may not possess a break off feature to control applied torque to lock the locking mechanism onto the post. An outside cylinder removal nut can be used for disengagement of the locking nut. This locking feature can restrict translation of a plate along the post or screw. A spherical tip on the outer cylinder can allow the plate to orbit about a fixed point on the axis of the post. In one embodiment, the inside cylinder is affixed to the plate and the outside cylinder is threaded away from the plate to lock the locking mechanism. This would restrict both orbital motion and translational motion.

In one embodiment, a locking mechanism includes a two piece off center axis locking nut with an outer sphere that can be twisted to a position which will align two inside hole features of the two components to allow insertion and smooth translation of a post or screw. Twisting of a proximal hex nut feature of the outside cylinder will rotate the two axes out of alignment to create an interference fit between the two piece locking nut which will expand the locking nut and grip the inside of a plate and the post or screw. The locking nut may or may not possess a break off feature to control applied torque to lock the locking mechanism onto the post. A proximal hex nut can be used for disengagement of the locking nut. This locking feature can restrict translation of the plate along the post. The outer spherical feature can be slit to allow expansion and interference within the plate to lock both orbital and translational motion. In one embodiment, the outer sphere does not have a slit, which will result in a restriction only of translational motion. A connection between the plate and post can be assembled with different length posts at the surgery to accommodate patient anatomy. In one embodiment, the post or screw can be removable from the plate by compressing a snap ring, removal of a set screw or pin, or loosening of a clamp.

It is contemplated that one or all of the components of the spinal implant may be disposable, peel-pack, pre-packed sterile devices. One or all of the components of the spinal implant may be reusable. The spinal implant may be configured as a kit with multiple sized and configured components.

Spinal implant10is employed, for example, with an open, mini-open or minimally invasive surgical technique to provide stabilization of a spine or other musculoskeletal structure. In preferred embodiments, the spinal implant10is configured to be integrated with instrumentation to allow for one hand insertion and implantation to stabilize two adjacent vertebrae for any surgical procedure requiring the same.

Turning now toFIGS. 1-8, there is illustrated components of a spinal implant10that includes a locking mechanism12in accordance with the principles of the present disclosure.

Referring toFIG. 1, locking mechanism12includes an inner surface14defining a tapered passageway16. Inner surface14is arcuately shaped and has a low surface roughness Ra. It is contemplated that inner surface14has various surface configurations, such as, for example, rough, threaded, arcuate, undulating, porous, semi-porous, dimpled, polished and/or textured. It is further contemplated that inner surface14is variously shaped, such as, for example, oval, oblong, triangular, square, hexagonal, polygonal, irregular, uniform and/or non-uniform. Inner surface14can be defined by a wall, such as, for example, a spinal plate18. Spinal plate18includes a first surface20and a second surface22configured to engage tissue, such as, for example, bone. Tapered passageway16extends between first and second surfaces20,22of plate18. Tapered passageway16has an arcuate cross section that uniformly decreases in diameter from first surface20to second surface22.

Locking mechanism12includes a tapered collet24configured to transition between a locking orientation and a non-locking orientation. In the locking orientation, collet24restricts the axial translation and/or axial rotation of a longitudinal member. In the non-locking orientation, collet24does not restrict the axial translation and/or axial rotation of longitudinal member34. Collet24is configured for disposal in tapered passageway16. Tapered collet24extends between a proximal end26and a distal end28. Tapered collet24has a conical configuration. In one embodiment, tapered collet24is a wedge. Collet24has an arcuate cross section configuration having a uniformly decreasing diameter from proximal to distal ends26,28corresponding to tapered passageway16. As collet24is inserted within passageway16in direction A as shown inFIG. 1, an interference fit between collet24and inner surface14forms such that collet24resists further axially translation through passageway16. Collet24includes an inner surface30defining a passageway32configured for disposal of a longitudinal member34, such as for example, a post, rod, or a screw, such as, for example, a bone screw. Passageway32has a uniform cross section along its length. Passageway32can have various cross section configurations, such as, for example, oval, oblong, triangular, square, hexagonal, and/or polygonal to accommodate variously shaped longitudinal members. In one embodiment, longitudinal member34is keyed to inner surface30of collet24such that longitudinal member34is restricted from rotating within passageway32. In one embodiment, spinal implant10includes a second spinal plate36disposed about a distal end38of longitudinal member34.

Collet24includes an abutting edge40disposed at distal end28configured to engage second surface22of wall or plate18in the non-locking orientation. Abutting edge40extends substantially perpendicular from an outer surface of collet24. Abutting edge40resists axial translation of collet24in a distal-proximate direction. In one embodiment, inner surface14of wall18includes an arcuate notch or groove42adjacent second surface22. Collet24includes an arcuate projection44disposed proximally adjacent to abutting edge40. Arcuate projection44is configured for disposal in arcuate groove42in the non-locking orientation. In the locking orientation, arcuate projection44abuts second surface22so as to resist axial translation of collet24in the distal-proximate direction. In one embodiment, collet24does not include arcuate projection44and inner surface14does not include groove42.

In operation, tapered collet24axially translates within tapered passageway16between the non-locking orientation and the locking orientation. In the non-locking orientation, as shown inFIG. 3, abutting edge40is in contact with second surface22and arcuate projection44is disposed in groove42. As collet24is axially translated in a proximal-distal direction, such as, for example, the direction shown by arrow A, collet24becomes increasingly resistive to further movement and the frictional engagement between collet24and inner surface14increases causing passageway32of collet24to constrict about longitudinal member34orienting collet24in the locking orientation, as shown inFIG. 2. In the locking orientation, collet24resists the axial translation of longitudinal member34within passageway32. In the locking orientation, arcuate projection44is disposed outside of passageway16and abuts second surface22resisting the movement of collet24in the distal-proximate direction.

In one embodiment, as shown inFIG. 4, spinal implant10includes a locking mechanism112, similar to locking mechanism12described above. Locking mechanism112includes collet24. Locking mechanism112further includes an arcuate collar46extending between a proximal end48and a distal end50. Arcuate collar46has a spherical shape having a rounded outer surface52. It is contemplated that arcuate collar46is variously shaped, such as, for example, those alternatives described herein. In one embodiment, arcuate collar46includes a slit54that extends between proximal and distal ends48,50so that collar46can be dilated. Arcuate collar46includes an inner surface56defining a tapered passageway58, similar to tapered passageway16described above. Tapered passageway58extends between proximal and distal ends48,50of arcuate collar46. Tapered passageway58is configured for disposal of collet24.

Locking mechanism112further includes a wall, such as, for example, a spinal plate118, similar to plate18described above. Plate or wall118has an inner surface114that defines a spherical passageway116configured for disposal of arcuate collar46such that arcuate collar46is rotatable within spherical passageway116. It is contemplated that passageway116is variously shaped, such as, for example, those alternatives described herein.

In operation, as tapered collet24is axially translated within passageway58towards distal end50of arcuate collar46in a proximal-distal direction, arcuate collar46dilates or expands about tapered collet24to engage inner surface114of plate118orienting collet24in the locking orientation. In the locking orientation, longitudinal member34is prevented from axially translating and/or rotating relative to inner surface114of plate118. In the locking orientation, as described above with regard toFIGS. 1-3, longitudinal member34is also prevented from axially translating within passageway32of tapered collet24. In the embodiment in which arcuate collar46does not include slit54, as tapered collet24is axially translated towards distal end50of arcuate collar46in the proximal-distal direction, arcuate collar46does not expand, which allows for the continued rotation of collar46relative to inner surface114of plate118, but still resists axial translation of longitudinal member34within passageway32of collet24.

In one embodiment, as shown inFIGS. 5 and 6A-6C, there is shown a locking mechanism212. Locking mechanism212includes an outer member, such as, for example, a hex nut214, and an inner member, such as, for example, a cylinder216disposable within hex nut214in a non-concentric configuration. Hex nut214includes an inner surface218defining a first passageway220. Inner surface218is threaded. It is contemplated that inner surface218has various surface configurations, such as, for example, rough, arcuate, undulating, porous, semi-porous, dimpled, polished and/or textured. First passageway220defines a first central axis along its length.

Cylinder216includes a threaded outer surface222threadedly engaged to inner surface218of hex nut214. It is contemplated that outer surface222has various surface configurations to enhance engagement with hex nut214, such as, for example, those alternatives described herein. Cylinder216defines a second central axis along its length. Cylinder216includes an inner surface224defining a second passageway226configured for disposal of longitudinal member34. Longitudinal member34is keyed to inner surface224such that when longitudinal member34is disposed in second passageway226, longitudinal member34is prevented from rotating relative to inner surface224of cylinder216. Second passageway226defines a third central axis along its length offset from the second central axis of cylinder216, as shown by217inFIG. 6A. Cylinder216has a wall thickness that varies along its circumference creating the offset217between second and third central axes of cylinder216and second passageway226, respectively. In one embodiment, the second central axis of cylinder216is offset from a central axis of hex nut214.

In operation, locking mechanism212rotates between a non-locking orientation and a locking orientation. When locking mechanism212is in the non-locking orientation, the first and third central axes are co-axial so as to receive longitudinal member34and longitudinal member34is movable relative to hex nut214and cylinder216. Once longitudinal member34is disposed within second passageway226, hex nut214or cylinder216is rotated with respect to one another. Upon rotation of hex nut214with respect to cylinder216, the first and third central axes become offset relative to one another, locking longitudinal member34relative to hex nut214and cylinder216. When longitudinal member34is fixed relative to hex nut214and cylinder216, locking mechanism212is in the locking orientation. When locking mechanism212is in the locking orientation, inner surfaces218,224of hex nut214and cylinder216, respectively, frictionally engage longitudinal member34in region230.

In one embodiment, shown inFIG. 7, a locking mechanism312is provided, similar to locking mechanism212described above with regard toFIGS. 5 and 6A-6C. Locking mechanism312includes an outer member314, similar to hex nut214described above. Outer member314extends between a cylindrically shaped proximal end316and a distal end318. Distal end318includes an arcuate collar320, similar to collar24described above with regard toFIG. 4. Outer member314includes an inner surface322that defines a first passageway324along its length. First passageway324defines a first central axis along its length.

Locking mechanism312includes an inner member, such as, for example, an inner cylinder326disposed with first passageway324. Cylinder326defines a second central axis along its length. Cylinder326includes an inner surface328defining a second passageway330configured for disposal of longitudinal member34. Longitudinal member34is keyed to inner surface328such that when longitudinal member34is disposed in second passageway330, longitudinal member34is prevented from rotating relative to inner surface328of cylinder326. Second passageway330defines a third central axis along its length offset from the second central axis of cylinder326, similar to locking mechanism212. Cylinder326has a wall thickness that varies along its circumference creating the offset between second and third central axis of cylinder326and second passageway330, respectively. In one embodiment, outer member314has a varying wall thickness along its circumference so that second central axis of cylinder326is offset from a central axis of outer member314.

Locking mechanism312further includes an inner surface332defining an arcuately shaped third passageway334. Third passageway334extends between surfaces336,338of a wall or plate340, similar to plate18described above. Arcuate collar320of outer member314is disposed with third passageway334between inner surface332of wall or plate340and an outer surface of cylinder326. With arcuate collar320disposed in third passageway334, outer member314is rotatable about an axis transverse to the first central axis.

In operation, locking mechanism312rotates between a non-locking orientation and a locking orientation. When locking mechanism312is in the non-locking orientation, the first and third central axes are in substantially co-axial alignment so as to receive longitudinal member34. Once longitudinal member34is disposed within second passageway330, outer member314and cylinder326are rotated with respect to one another. Upon rotation of outer member314with respect to cylinder326, for example, the first and third central axes become increasingly offset causing outer member314to dilate or expand such that collar320forcefully engages inner surface332of wall340. When locking mechanism312is in the locking orientation, the first and third central axes are offset such that inner surfaces328,322of cylinder326and outer member314, respectively, frictionally engage longitudinal member34in region344preventing axial and/or rotational movement of longitudinal member34. In one embodiment, outer member314does not dilate or expand as outer member314is rotated with respect to cylinder326such that longitudinal member34is rotatable.

In one embodiment, shown inFIG. 8, a locking mechanism412is provided, similar to locking mechanism312described above. Locking mechanism412includes a wall, such as, for example, a spinal plate418. Plate418includes an inner surface420defining an arcuately shaped first passageway422.

Locking mechanism412includes an outer member, such as, for example, an outer collar424, similar to collar24described above with regard toFIG. 4. Collar424is disposable with passageway422of plate218. Collar424includes an inner surface426defining an arcuately shaped second passageway428having a first central axis along its length.

Locking mechanism412includes an inner member430, similar to outer member314described above, extending between a proximal end432and a distal end434. Proximal end432includes a hex nut and distal end434includes an inner arcuate collar434. Inner arcuate collar434is disposable with second passageway428. Inner member430includes an inner surface436defining a third passageway438extending between proximal and distal ends432,434. Third passageway438is configured for disposal of longitudinal member34. Third passageway438defines a third central axis along its length offset from the second central axis.

In operation, locking mechanism412rotates between a non-locking orientation and a locking orientation. When locking mechanism412is in the non-locking orientation, the first and third central axes are co-axial so as to receive longitudinal member34such that longitudinal member is movable relative to inner member430and collar424. Once longitudinal member34is disposed within third passageway438, outer collar424and inner member430are rotated with respect to one another. Upon rotation of collar424with respect to inner member430, for example, the first and third central axes become offset causing outer collar424to dilate or expand such that collar424forcefully engages inner surface420of wall418. When locking mechanism412is in the locking orientation, with first and third central axes being offset, inner surfaces436,426of inner member430and collar424, respectively, frictionally engage longitudinal member34in region440preventing axial and rotational movement of longitudinal member34. In one embodiment, outer collar424does not dilate or expand as collar424rotates with respect to inner member430such that longitudinal member34remains rotatable.

In one embodiment, spinal implant10may be treated with or include an agent, which may be disposed, packed or layered within, on or about the components and/or surfaces of spinal implant10. It is envisioned that the agent may include bone growth promoting material, such as, for example, bone graft to enhance spinal implant10with spinal processes of vertebrae.

It is contemplated that the agent may include therapeutic polynucleotides or polypeptides. It is further contemplated that the agent may include biocompatible materials, such as, for example, biocompatible metals and/or rigid polymers, such as, titanium elements, metal powders of titanium or titanium compositions, sterile bone materials, such as allograft or xenograft materials, synthetic bone materials such as coral and calcium compositions, such as HA, calcium phosphate and calcium sulfite, biologically active agents, for example, gradual release compositions such as by blending in a bioresorbable polymer that releases the biologically active agent or agents in an appropriate time dependent fashion as the polymer degrades within the patient. Suitable biologically active agents include, for example, BMP, Growth and Differentiation Factors proteins (GDF) and cytokines. The components of fixation system10can be made of radiolucent materials such as polymers. Radiomarkers may be included for identification under x-ray, fluoroscopy, CT or other imaging techniques. It is envisioned that the agent may include one or a plurality of therapeutic agents and/or pharmacological agents for release, including sustained release, to treat, for example, pain, inflammation and degeneration.