Monoblock implant and method for cervical spine fusion surgery
A monoblock implant for fusing a cervical motion segment includes (a) an interbody portion configured to be positioned between superior and inferior vertebral bodies, of the cervical motion segment, with a first side of the interbody portion facing a first uncinate joint of the cervical motion segment and a second side of the interbody portion facing a second uncinate joint of the cervical motion segment, (b) a first wing extending away from the first side to extend into the first uncinate joint, and (c) a second wing extending away from the second side to extend into the second uncinate joint.
1. A monoblock implant for fusing a cervical motion segment, comprising:
an interbody portion configured to be positioned between superior and inferior vertebral bodies of the cervical motion segment, with a first side of the interbody portion facing a first uncinate joint of the cervical motion segment and a second side of the interbody portion facing a second uncinate joint of the cervical motion segment;
a first wing extending away from the first side to extend into the first uncinate joint; and
a second wing extending away from the second side to extend into the second uncinate joint;
the interbody portion including a superior interbody surface configured to face the superior vertebral body and an inferior interbody surface configured to face the inferior vertebral body, maximum distance between the superior and inferior interbody surfaces defining an axial extent of the interbody portion in an axial dimension, each of the first and second wings being oriented at an oblique angle to the axial extent to reach beyond the superior interbody surface in the axial dimension; and
each of the first and second wings including:
a superior wing surface configured to face the superior vertebral body of the cervical motion segment, the superior wing surface being oriented at a first oblique angle to the superior interbody surface; and
an inferior wing surface configured to face the inferior vertebral body of the cervical motion segment, the inferior wing surface being oriented at a second oblique angle to the inferior interbody surface; and
wherein each of the superior wing surface and the inferior wing surface of the first and second wings, respectively, extends axially beyond the superior interbody surface in the axial dimension, and each of the first wing and the second wing form at least one void for accommodating a fusion promoting material.
2. The monoblock implant of claim 1 , being a rigid single piece.
3. The monoblock implant of claim 1 , the axial extent decreasing along an anterior-to-posterior direction.
4. The monoblock implant of claim 1 , distance by which each of the first and second wings extends beyond the superior interbody surface decreasing along the anterior-to-posterior direction.
5. The monoblock implant of claim 1 , wherein the superior wing surface being oriented at the first oblique angle, in a range between 10 and 75 degrees, to the superior interbody surface; and
the second oblique angle being at least as large as the first oblique angle.
6. The monoblock implant of claim 5 , the superior wing surface forming a continuation of the superior interbody surface, the inferior wing surface forming a continuation of the inferior interbody surface.
7. The monoblock implant of claim 1 , wherein a distance between the superior and inferior wing surfaces decreasing with distance from the interbody portion.
8. The monoblock implant of claim 7 , for each of the first and second wings, the superior and inferior wing surfaces converging at a rounded edge farthest from the interbody portion.
9. The monoblock implant of claim 1 , the first and second sides being non-parallel such that lateral width of the interbody portion decreases along an anterior-to-posterior direction.
10. The monoblock implant of claim 1 , at least part of each of the first and second wings being porous.
11. The monoblock implant of claim 1 , wherein the interbody portion forms one or more interbody voids for accommodating the fusion promoting material.
12. The monoblock implant of claim 11 , at least one of the voids occupying at least 90 percent of a volume of an envelope spanned by the interbody portion.
13. A method for fusing a cervical motion segment, comprising:
inserting, from an anterior side of the cervical motion segment, a rigid, single-piece, monoblock implant between superior and inferior vertebral bodies of the cervical motion segment, the monoblock implant spanning from a first location within a first uncinate joint of the cervical motion segment, across intervertebral disk space of the cervical motion segment, to a second location within a second uncinate joint of the cervical motion segment; and
wherein the monoblock implant having an interbody portion configured to be positioned between the superior and inferior vertebral bodies, of the cervical motion segment, with a first side of the interbody portion facing the first uncinate joint of the cervical motion segment and a second side of the interbody portion facing the second uncinate joint of the cervical motion segment;
a first wing extending away from the first side to extend into the first location within the first uncinate joint; and
a second wing extending away from the second side to extend into the second location within the second uncinate joint;
the interbody portion including a superior interbody surface configured to face the superior vertebral body and an inferior interbody surface configured to face the inferior vertebral body, maximum distance between the superior and inferior interbody surfaces defining an axial extent of the interbody portion in an axial dimension; and
each of the first and second wings including:
a superior wing surface configured to face the superior vertebral body of the cervical motion segment, the superior wing surface being oriented at a first oblique angle to the superior interbody surface;
an inferior wing surface configured to face the inferior vertebral body of the cervical motion segment, the inferior wing surface being oriented at a second oblique angle to the inferior interbody surface; and
wherein each of the superior wing surface and the inferior wing surface of the first and second wings, respectively, extends axially beyond the superior interbody surface in the axial dimension, and each of the first wing and the second wing define at least one void for accommodating a fusion promoting material.
14. The method of claim 13 , each of the first location and the second location being axially superior to the intervertebral disk space.
15. The method of claim 13 , further comprising, prior to the step of inserting, modifying at least one of inferior surface of the superior vertebral body and superior surface of the inferior vertebral body to accommodate a shape of the monoblock implant.
16. The method of claim 15 , the step of modifying comprising removing tissue from each of the inferior surface and the superior surface at an interface between the intervertebral disk space and each of the first and second uncinate joints.
17. The method of claim 13 , further comprising promoting fusion, via the monoblock implant, between cortical bone of the superior and inferior vertebral bodies in each of the first and second uncinate joints.
18. The method of claim 17 , the step of inserting further comprising carrying, to the intervertebral disk space, bone graft material in one or more voids of the monoblock implant.