Expandable intervertebral implants
Interbody spacers are expandable horizontally and vertically by an application of axial force, and lockable in an expanded configuration. The spacers include support members interconnected to end bodies by pivotable link members. The spacers are introduced between vertebral bodies in a compressed configuration and expanded to fill the intervertebral space and provide support and selective lordotic correction. Graft material may be introduced into the expanded spacer. Provisional and/or supplementary locking means lock the spacers in the expanded configuration. Embodiments of the spacers include symmetrically and asymmetrically configured spacers. Methods of expansion include symmetric expansion or asymmetric expansion along each of two directions.
1. An intervertebral spacer for implantation between first and second vertebral bodies of a portion of a spine, the spacer having a first end and a second end and a first axis extending therebetween, the spacer comprising:
a first support member comprising a first upper body and a first lower body;
a second support member;
a first end body located at the spacer first end and connected to the first and second support members;
a second end body located at the spacer second end and connected to the first and second support members, wherein the axial force acts upon at least one of the end bodies to expand the spacer; and
a plurality of individual links, each link extending between and directly connecting one of the end bodies with one of the first and second support members;
wherein the intervertebral spacer is expandable by an application of axial force along the first axis to expand the first support member away from the second support member along a first direction, and to expand the first upper body away from the first lower body along a second direction;
wherein the first direction is perpendicular to the first axis, and wherein the second direction is perpendicular to the first axis and to the first direction; and
wherein each of the upper and lower bodies includes a first recess in communication with a second recess, wherein the first recess is recessed deeper within the body than the second recess.
2. The intervertebral spacer of claim 1 , wherein the first direction is configured to be approximately parallel relative to the vertebral body endplates and the second direction is configured to be approximately perpendicular relative to the vertebral body endplates.
3. The intervertebral spacer of claim 1 , wherein the spacer is bilaterally symmetrical relative to at least one plane extending along the first axis.
4. The intervertebral spacer of claim 1 , wherein the first end body is drawn toward to the second end body along the first axis to expand the spacer.
5. The intervertebral spacer of claim 1 , wherein each of the individual links rotates laterally outward relative to the end body to which it is connected, to expand the first support member away from the second support member along the first direction.
6. The intervertebral spacer of claim 5 , wherein each of the individual links includes at least one stop surface, wherein the stop surface abuts one of the end bodies to limit expansion of the spacer along the first direction.
7. The intervertebral spacer of claim 1 , wherein a ramp connects the first recess and the second recess, and wherein one of the individual links is urged from the first recess along the ramp into the second recess to expand the upper body away from the lower body along the second direction.
8. The intervertebral spacer of claim 1 , wherein the spacer further comprises:
a collapsed configuration in which the first support member is immediately adjacent the second support member, and the first lower body abuts the first upper body;
a laterally expanded configuration wherein the first support member is expanded away from the second support member along the first direction;
a vertically expanded configuration wherein the first upper body is expanded away from the first lower body along the second direction; and
a provisional locking structure which is integrally formed into each of the first and second support members, wherein the provisional locking structure prevents unintentional collapse of the spacer out of the vertically expanded configuration.
9. The intervertebral spacer of claim 8 , further comprising a supplementary locking structure, wherein the supplementary locking structure is engageable with at least one of the first and second end bodies to lock the spacer in the vertically expanded configuration.
10. The intervertebral spacer of claim 8 , wherein the second support member comprises a second upper body and a second lower body;
wherein when the spacer is in the collapsed configuration the second lower body abuts the second upper body; and
wherein when the spacer is in the vertically expanded configuration the second upper body is expanded away from the second lower body along the second direction.
11. The intervertebral spacer of claim 1 , wherein at least one of the first upper body or first lower body includes an outer surface which is sloped with respect to the first axis, the sloped outer surface providing an integrated lordotic correction when the intervertebral spacer is implanted between first and second vertebral bodies of a portion of a spine.
12. A method for implanting an intervertebral spacer between first and second vertebral bodies of a portion of a spine, the spacer having a first end and a second end and a first axis extending therebetween, the method comprising:
inserting a spacer between first and second vertebral bodies of a portion of a spine, the spacer comprising a first support member comprising a first upper body and a first lower body, and a second support member,
wherein the spacer further comprises:
a first end body located at the spacer first end and connected to the first and second support members and a second end body located at the spacer second end and connected to the first and second support members, and
a plurality of individual links, each link directly connecting one of the end bodies with one of the first and second support members;
wherein each of the upper and lower bodies includes a first recess in communication with a second recess, wherein a ramp connects the first recess and the second recess;
providing an application of axial force along the first axis, wherein the axial force moves the first support member away from the second support member along a first direction and moves the first upper body away from the first lower body along a second direction, wherein the first direction is perpendicular to the first axis, and wherein the second direction is perpendicular to the first axis and to the first direction;
drawing the first end body toward the second end body along the first axis to expand the spacer;
rotating each of the individual links laterally outward relative to the end body to which it is connected, to expand the first support member away from the second support member along the first direction; and
urging at least one of the individual links from the first recess along the ramp into the second recess to expand the upper body away from the lower body along the second direction.
13. The method of claim 12 , wherein the axial force along the first axis expands the spacer laterally along the first direction and then sequentially expands the spacer vertically along the second direction only after lateral expansion is completed.
14. The method of claim 12 , wherein each of the individual links includes at least one stop surface, the method further comprising:
abutting the at least one stop surface against of the end bodies to limit expansion of the spacer along the first direction.
15. The method of claim 12 , wherein the spacer further comprises a collapsed configuration in which the first support member is immediately adjacent the second support member, the first lower body abuts the first upper body, the method further comprising:
moving the first support member away from the second support member along the first direction, wherein the spacer attains a laterally expanded configuration;
moving the first upper body away from the first lower body along the second direction, wherein the spacer attains a vertically expanded configuration; and
provisionally locking the spacer in the vertically expanded configuration wherein locking the spacer prevents unintentional collapse of the spacer out of the vertically expanded configuration.
16. The method of claim 15 , wherein the spacer further comprises a supplementary locking structure, the method further comprising:
engaging the supplementary locking structure with at least one of the first and second end bodies to lock the spacer in the vertically expanded configuration.
17. The method of claim 15 , wherein the second support member comprises a second upper body and a second lower body, the method further comprising:
moving wherein the second upper body away from the second lower body along the second direction to attain the vertically expanded configuration.