Plate/screw locking mechanism devices, systems and methods
View Patent ↗The present disclosure relates, in some embodiments, to locking mechanisms for a fastener (e.g., a bone screw) and associated devices, systems, and methods. According to some embodiments, a lockable bone plate assembly may comprise, for example, a bone plate and a bone screw assembly. A bone plate may comprise, in some embodiments, at least one through hole, the at least one through hole having at least one bone plate hole circumferential recess. According to some embodiments, a bone screw assembly may comprise (a) a bone screw, (b) at least one deployable protrusion, and/or (c) a protrusion driver. The present disclosure further relates, in some embodiments, to methods for bone (e.g., vertebral) fixation. For example, a method may comprise contacting at least a portion of a spine (e.g., cervical spine) of a subject with a lockable bone plate assembly.
1. A bone screw assembly, comprising:
a bone screw;
a deployable protrusion having a stowed position at least partially within the bone screw and a deployed position at least partially protruding from the bone screw, the deployable protrusion being operable to engage a recess of a bone plate; and
a protrusion driver in mechanical communication with the deployable protrusion and operable to drive the deployable protrusion from the stowed position to the deployed position, wherein
the protrusion driver includes an outer circumferential cam surface, and
the deployable protrusion includes a domed end, the domed end being disposed radially outward of the cam surface and in contact with the outer circumferential cam surface.
2. The bone screw assembly according to claim 1 , wherein the protrusion driver is operable to move the deployable protrusion radially outwardly from the stowed position to the deployed position.
3. The bone screw assembly according to claim 1 , wherein the protrusion driver has a deployed position corresponding to the deployed position of the deployable protrusion.
4. The bone screw assembly according to claim 1 , wherein the protrusion driver is operable to lock in the deployed position.
5. The bone screw assembly according to claim 1 , wherein
the bone screw includes a central, longitudinal axis and a bone screw head having at least one notch, and
each of the bone screw and the bone screw head includes a torque surface operable to receive a torque and translate the torque to rotation of the bone screw about the central, longitudinal axis.
6. The bone screw assembly according to claim 1 , wherein the bone screw has a central longitudinal axis and includes:
a bone screw body having threads that taper to a tip; and
a bone screw head fixed to the bone screw body on an end opposite to the tip.
7. The bone screw assembly according to claim 6 , wherein the bone screw head includes an annular groove encircling a notch.
8. The bone screw assembly according to claim 6 , wherein
the bone screw head includes a cavity having a cavity inner surface, and
the cavity inner surface includes a stowed recess and a deployed recess, the deployed recess being closer to the tip than the stowed recess.
9. The bone screw assembly according to claim 1 , wherein a contacting surface between the protrusion driver and the deployable protrusion having a first radial distance in the stowed position and a second radial distance different from the first radial distance in the deployed position.
10. The bone screw assembly according to claim 1 , wherein a profile of an outer circumference of the cam surface varies radially in a cross-section taken transverse to a rotational axis of the protrusion driver.
11. The bone screw assembly according to claim 1 , wherein the protrusion driver includes a slot operable to permit the protrusion driver to be radially compressed.
12. The bone screw assembly according to claim 1 , wherein
the bone screw assembly includes a plurality of the deployable protrusions, each having a domed end in contact with the cam surface, and
the plurality of deployable protrusions are distributed radially about a longitudinal axis of the bone screw.
13. A bone screw assembly, comprising:
a bone screw;
a deployable protrusion having a stowed position at least partially within the bone screw and a deployed position at least partially protruding from the bone screw, the deployable protrusion being operable to engage a recess of a bone plate; and
a protrusion driver in mechanical communication with the deployable protrusion and operable to drive the deployable protrusion from the stowed position to the deployed position, wherein
the protrusion driver includes a cam surface,
the deployable protrusion includes a domed end in contact with the cam surface,
the bone screw has a central longitudinal axis and includes:
a bone screw body having threads that taper to a tip; and
a bone screw head fixed to the bone screw body on an end opposite to the tip,
the bone screw head includes an annular groove encircling a notch,
the protrusion driver includes on its outer circumferential surface at least one axial groove, at least one axial deep recess, and at least one axial shallow recess between the axial groove and the axial deep recess,
the at least one deep recess is configured to engage the deployable protrusion in its stowed position, and
the at least one shallow recess is configured to engage the deployable protrusion in its deployed position.
14. A bone screw assembly, comprising:
a bone screw having a central longitudinal axis and including:
a bone screw body having threads that taper to a tip, and
a bone screw head fixed to the bone screw body on an end opposite to the tip, the bone screw head including a cavity having a cavity inner surface, and the cavity inner surface including a stowed recess and a deployed recess, the deployed recess being closer to the tip than the stowed recess;
a deployable protrusion having a stowed position at least partially within the bone screw and a deployed position at least partially protruding from the bone screw, the deployable protrusion being operable to engage a recess of a bone plate;
a protrusion driver in mechanical communication with the deployable protrusion and operable to drive the deployable protrusion from the stowed position to the deployed position; and
an annular bone screw race in the central cavity having a stowed position and a deployed position, the annular bone screw race including
a first end,
an outer circumferential surface including at least one circumferential nub, and
a second end opposite the first end, wherein
the protrusion driver includes a cam surface,
the deployable protrusion includes a domed end in contact with the cam surface, and
the nub engages the stowed circumferential recess in the stowed position of the race and the nub engages the deployed circumferential recess in the deployed position of the race.
15. The bone screw assembly according to claim 14 , wherein the deployable protrusion includes a bone screw pin having a generally cylindrical shape, a proximal end in mechanical communication with the cam surface and a distal end engageable with the at least one bone plate hole circumferential recess.
16. The bone screw assembly according to claim 15 , wherein the annular bone screw race includes a slot spanning its radial and longitudinal thickness.
17. The bone screw assembly according to claim 16 , wherein the annular bone screw race includes at least one notch distinct from the slot.
18. The bone screw assembly according to claim 16 , wherein the annular bone screw race includes a notch that is contiguous with the slot.
19. The bone screw assembly according to claim 15 , wherein the annular bone screw race includes a central aperture having a threaded central aperture surface.
20. A method of vertebral fixation, comprising:
contacting at least a portion of a spine of a subject with a lockable bone plate assembly, the lockable bone plate assembly including:
a bone plate including a through hole having a recess, and
a bone screw assembly including
a bone screw,
a deployable protrusion having a stowed position at least partially within the bone screw and a deployed position at least partially protruding from the bone screw, the deployable protrusion being operable to engage a recess of a bone plate, and
a protrusion driver in mechanical communication with the deployable protrusion and operable to drive the deployable protrusion from the stowed position to the deployed position, wherein
the protrusion driver includes an outer circumferential cam surface, and
the deployable protrusion includes a domed end, the domed end being disposed radially outward of the cam surface and in contact with the outer circumferential cam surface.
21. The method of vertebral fixation according to claim 20 , wherein the at least a portion of the spine of the subject includes at least a portion of the subject's cervical spine.