Intervertebral implants
An interbody implant can comprise a cage and a porous structure. The cage can comprise an anterior segment, a medial segment, a posterior segment and a lateral segment contiguously connected to each other to define an interior space. The porous structure can be located in the interior space and can be bounded by the cage. The porous structure can comprise opposed superior and inferior surfaces exposed through the cage, an internal cavity located in an interior of the porous structure, and a plurality of ports connecting the internal cavity to the superior and inferior surfaces. A superior-inferior stiffness of the interbody implant can be defined by the porous structure. The porous structure can be compressed within a patient by movement of the spine to biologically stimulate bone growth in vertebrae adjacent the interbody implant. The implant can be configured for lateral, anterior and posterior insertion at different spine levels.
1 . An interbody implant comprising:
a first cage defining a first interior space;
a second cage defining a second interior space; and
a monolithic porous structure bounded by the first cage and the second cage, the monolithic porous structure comprising:
a first panel located in the first interior space of the first cage, the first panel including a first surface exposed through the first cage, the first surface including a first plurality of pores defined by a first lattice structure;
a second panel located in the second interior space of the second cage, the second panel including a second surface exposed through the second cage, the second surface including a second plurality of pores defined by a second lattice structure; and
a third panel defining an interior cavity able to receive bone-growth-promoting material through a plurality of openings,
wherein a plurality of ports connect the interior cavity within the third panel to the first and second plurality of pores in the first and second surfaces of the first and second panels, respectively, to distribute the bone-growth-promoting material within the interior cavity through the first and second plurality of pores while maintaining a stiffness for the monolithic porous structure that also permits compression of the monolithic porous structure.
2 . The interbody implant of claim 1 , wherein a portion of the third panel is positioned between the first and second cages such that the first and second cages are separated from making contact, to permit the monolithic porous structure to compress and without interference during compression caused by contact between the first and second cages.
3 . The interbody implant of claim 1 , further comprising a socket for coupling with a shaft of an insertion tool.
4 . The interbody implant of claim 3 , wherein the socket includes a first portion formed from a first segment of the first cage and a second portion formed from a second segment of the second cage opposite the first cage about the third panel of the monolithic porous structure such that the first and second portions of the socket are separated from making contact, and wherein the first and second portions of the socket are each threaded.
5 . The interbody implant of claim 3 , wherein the socket is a formed component that is insertable into an opening defined in the third panel, wherein the opening is dimensioned to have a first portion of the third panel of the monolithic porous structure located between the first cage and the socket and a second portion of the third panel of the monolithic porous structure located between the second cage and the socket such that the first cage, the second cage, and the socket are separated from making contact, and wherein the socket includes a bore that is threaded.
6 . The interbody implant of claim 1 , further comprising a support wall extending across the interior cavity to separate the interior cavity into separate sub-cavities, wherein the support wall is located at a center of the interbody implant.
7 . The interbody implant of claim 6 , wherein the support wall is porous with a plurality of openings, to allow for bone-growth-promoting material to distribute between the sub-cavities within the middle panel.
8 . The interbody implant of claim 1 , further comprising a third plurality of pores defined by a third lattice structure within an exterior surface of the third panel, wherein the interior cavity within the third panel is in communication with the third plurality of pores to distribute the bone-growth-promoting material within the interior cavity through the third plurality of pores while maintaining the stiffness for the monolithic porous structure that also permits compression of the monolithic porous structure.
9 . The interbody implant of claim 1 , wherein the first cage comprises an anterior segment, a medial segment, a posterior segment, and a lateral segment contiguously connected to each other to define the first interior space, and wherein the second cage comprises an anterior segment, a medial segment, a posterior segment, and a lateral segment contiguously connected to each other to define the second interior space.
10 . The interbody implant of claim 9 , wherein the first surface of the first panel is a superior surface and the second surface of the second panel is an inferior surface,
wherein superior surfaces of the anterior segment, the medial segment, the posterior segment, and the lateral segment of the first cage are substantially flush with the superior surface of the first panel, and
wherein inferior surfaces of the anterior segment, the medial segment, the posterior segment, and the lateral segment of the second cage are substantially flush with the inferior surface of the second panel.
11 . The interbody implant of claim 9 , wherein the third panel includes an anterior surface, a medial surface, a posterior surface, and a lateral surface,
wherein anterior surfaces of the anterior segments of the first and second cages are substantially flush with the anterior surface of the third panel,
wherein medial surfaces of the medial segments of the first and second cages are substantially flush with the medial surface of the third panel,
wherein posterior surfaces of the posterior segments of the first and second cages are substantially flush with the posterior surface of the third panel, and
wherein lateral surfaces of the lateral segments of the first and second cages are substantially flush with the lateral surface of the third panel.
12 . The interbody implant of claim 1 , further comprising a wedge structure located on an end of the interbody implant, wherein the wedge structure comprises tapered surfaces on the first and second panels of the monolithic porous structure and corresponding portions of the first and second cages that together form a thinnest portion of the interbody implant.
13 . The interbody implant of claim 1 , wherein:
a first side of the first and second cages and the monolithic porous structure are curved so that a first side of the interbody implant is convex; and
a second side of the first and second cages and the monolithic porous structure are curved so that a second side of the interbody implant is concave.
14 . An intervertebral implant, comprising:
a monolithic porous structure formed of a porous material having a plurality of openings in a plurality of exterior surfaces, the monolithic porous structure shaped to define:
an interior cavity able to receive and store bone-graft material;
a superior panel;
an inferior panel;
a middle panel separating the superior panel and the inferior panel to define the interior cavity; and
a plurality of passages extending through the monolithic porous structure to intersect the interior cavity and distribute the bone-graft material within the interior cavity through the plurality of openings while maintaining a longitudinal stiffness for the monolithic porous structure that also permits compression of the monolithic porous structure;
a first cerclage cage surrounding the monolithic porous structure; and
a second cerclage cage surrounding the monolithic porous structure such that the longitudinal stiffness of the intervertebral implant is defined by the monolithic porous structure.
15 . The intervertebral implant of claim 14 , wherein
the superior panel includes a superior exterior surface of the plurality of exterior surfaces with a first plurality of openings extending through the superior panel to partially define the plurality of longitudinal passages; and
the inferior panel includes an inferior exterior surface of the plurality of exterior surfaces with a second plurality of openings extending through the inferior panel to partially define the plurality of longitudinal passages.
16 . The intervertebral implant of claim 15 , wherein the middle panel includes:
a posterior exterior surface of the plurality of exterior surfaces with a third plurality of openings extending through the middle panel and in communication with the interior cavity; and
an anterior exterior surface of the plurality of exterior surfaces with at least one anterior opening through which the bone graft material may be inserted into the interior cavity.
17 . The intervertebral implant of claim 14 , further comprising a socket able to receive an insertion tool, wherein the socket does not connect the first cerclage cage and the second cerclage cage.
18 . An intervertebral implant for implantation with an insertion tool, the intervertebral implant comprising:
a monolithic porous structure formed of a porous material having a plurality of openings in a plurality of exterior surfaces, the monolithic porous structure shaped to define:
an interior cavity able to receive and store bone-graft material; and
a plurality of longitudinal passages extending through the monolithic porous structure to intersect the interior cavity and distribute the bone-graft material within the interior cavity through the plurality of openings while maintaining a longitudinal stiffness for the monolithic porous structure that also permits compression of the monolithic porous structure;
a first cerclage cage surrounding the monolithic porous structure;
a second cerclage cage surrounding the monolithic porous structure and uncoupled from the first cerclage cage such that the longitudinal stiffness of the intervertebral implant is defined by the monolithic porous structure; and
a socket able to receive the insertion tool, wherein the socket includes a first portion formed from a first segment of the first cerclage cage and a second portion formed from a second segment of the second cerclage cage opposite the first cerclage cage.
19 . The intervertebral implant of claim 18 , wherein the first and second portions of the socket are separated from making contact by the monolithic porous structure, and wherein the first and second portions of the socket are threaded.
20 . The intervertebral implant of claim 18 , wherein the socket is a formed component that is insertable into an opening defined in the monolithic porous structure, wherein the opening is dimensioned to have a first portion of the monolithic porous structure is located between the first cerclage cage and the socket and a second portion of the monolithic porous structure is located between the second cerclage cage and the socket such that the first cerclage cage, the second cerclage cage, and the socket are separated from making contact, and wherein the socket includes a bore that is threaded.