Spinal Implants for Rotationally Adjusting Vertebrae

Abstract

A spinal implant adapted to be positioned within a disc space between adjacent vertebrae includes a first intradiscal element, a second intradiscal element, and a coupling mechanism. The first and second intradiscal elements include respective first and second outer surfaces adapted to be positioned adjacent an endplate of respective first and second adjacent vertebrae. The first and second intradiscal elements further include respective first and second medial surfaces that are opposite the respective first and second outer surfaces, where the second medial surface is adapted to generally face the first medial surface upon assembly of the first intradiscal element with the second intradiscal element. The coupling mechanism is associated with the first and second medial surfaces and is adapted to provide relative rotational movement between the first and second intradiscal elements in a plane generally parallel with the first and second medial surfaces.

What is claimed is: 
     
         1 . A spinal implant adapted to be positioned within a disc space between adjacent vertebrae, the implant comprising:
 a first intradiscal element comprising a first outer surface adapted to be positioned adjacent an endplate of a first one of the adjacent vertebrae and comprising a first medial surface that is opposite the outer surface;   a second intradiscal element comprising a second outer surface adapted to be positioned adjacent an endplate of a second one of the adjacent vertebrae and comprising a second medial surface that is opposite the outer surface and adapted to generally face the first medial surface upon assembly of the first intradiscal element with the second intradiscal element; and   coupling mechanism that is associated with the first and second medial surfaces and that is adapted to provide relative rotational movement between the first and second intradiscal elements in a plane generally parallel with the first and second medial surfaces.   
     
     
         2 . The spinal implant of  claim 1 , wherein the coupling mechanism provides for the relative rotational movement about an axis at a center portion of the first and second medial surfaces. 
     
     
         3 . The spinal implant of  claim 2 , wherein the coupling mechanism comprises a post element extending from a center portion of one of the first and second medial surfaces and an aperture provided in a center portion of the other of the first and second medial surfaces, the post element and aperture adapted to be coupled together. 
     
     
         4 . The spinal implant of  claim 3 , wherein the post element comprises a bulbous distal end, and the aperture comprises an enlarged lower portion that receives the bulbous distal end of the post element. 
     
     
         5 . The spinal implant of  claim 4 , wherein the coupling mechanism further comprises a snap ring adapted to be positioned about a neck of the post element proximal of the bulbous distal end, and the aperture further comprises a circumferential chamber into which the snap ring is able to be engaged. 
     
     
         6 . The spinal implant of  claim 2 , wherein the coupling mechanism comprises an interconnecting rail and channel assembly comprising at least one rail and at least one cooperating channel for receiving one of the at least one rail, wherein at least one rail is provided on one of the first and second intradiscal elements and at least one channel is provided on the other of the first and second intradiscal elements, wherein the at least one rail is adapted to become interconnected with the at least one channel within a limited rotational range by bringing the first and second intradiscal elements together with their first and second medial surfaces facing each other with a rotational offset that is outside of the limited rotational range, and rotating the two intradiscal elements relative to one another to be within the limited rotational range and thereby engage the rail within the channel. 
     
     
         7 . The spinal implant of  claim 6 , wherein the interconnecting rail and channel assembly is provided on the first and second medial surfaces at a location that is away from the axis of rotation that is located in the center portion of the first and second medial surfaces. 
     
     
         8 . The spinal implant of  claim 6 , wherein the interconnecting rail and channel assembly comprises at least two semi-circular rails and two complementary semi-circular channels. 
     
     
         9 . The spinal implant of  claim 8 , wherein a first one of the at least two semi-circular rails and a first one of the at least two semi-circular channels are positioned on respective ones of the first and second medial surfaces at a location that is generally at a mid-point between the center portion of the first and second medial surfaces and a proximal end of the first and second medial surfaces, and a second one of the at least two semi-circular rails and a second one of the at least two semi-circular channels are positioned on respective ones of the first and second medial surfaces at a location that is generally at a mid-point between the center portion of the first and second medial surfaces and a distal end of the first and second medial surfaces. 
     
     
         10 . The spinal implant of  claim 8 , wherein a first one of the at least two semi-circular rails and a first one of the at least two semi-circular channels are positioned on respective ones of the first and second medial surfaces at a location that is generally at a proximal end of the first and second medial surfaces, and a second one of the at least two semi-circular rails and a second one of the at least two semi-circular channels are positioned on respective ones of the first and second medial surfaces at a location that is generally at a distal end of the first and second medial surfaces. 
     
     
         11 . The spinal implant of  claim 6 , wherein a first rail of the at least one rail is a L-shaped rail and a corresponding first channel of the at least one channel is L-shaped in a complementary fashion to allow the coupling of the first rail with the first channel. 
     
     
         12 . The spinal implant of  claim 6 , wherein a first rail of the at least one rail is T-shaped and a corresponding first channel of the at least one channel is T-shaped in a complementary fashion to provide for the coupling of the first rail with the first channel. 
     
     
         13 . The spinal implant of  claim 6 , wherein a first rail of the at least one rail is provided at an acute angle with respect to the medial surface upon which the first rail is provided and a corresponding first channel of the at least one channel provided at the same acute angle with respect to the medial surface in which the first channel is provided, to provide for the coupling of the first rail with the first channel. 
     
     
         14 . The spinal implant of  claim 6 , wherein the at least one rail comprises a first array of ridges on a first surface of the rail, and the at least one channel comprises a second array of ridges on a second surface of the channel, wherein when the first intradiscal member is assembled with the second intradiscal member, wherein the first and second arrays are configured such that ridges of the first array fall within corresponding ridge valleys of the second array to resist the relative rotational movement of the first intradiscal element in relation to the second intradiscal element. 
     
     
         15 . The spinal implant of  claim 1 , further comprising a rotational movement resistance mechanism adapted to resist rotational movement from a plurality of incremented relative rotational positions of the first intradiscal element in relation to the second intradiscal element. 
     
     
         16 . The spinal implant of  claim 1 , wherein the rotational movement resistance mechanism comprises a first array of ridges provided on one of the first and second medial surfaces, and a second array of ridges provided on the other of the first and second medial surfaces, wherein the first and second arrays are configured such that ridges of the first array fall within corresponding ridge valleys of the second array to resist the relative rotational movement of the first intradiscal element in relation to the second intradiscal element. 
     
     
         17 . The spinal implant of  claim 16 , wherein the first and second arrays are provided on their respective medial surfaces at a location that at least in part encircles an axis of rotation of the relative rotational movement between the first and second intradiscal elements. 
     
     
         18 . The spinal implant of  claim 17 , wherein the first and second arrays are provided in a circular pattern, with each of the individual ridge peaks of the first and second arrays being aligned with lines that emanate from the axis of rotation. 
     
     
         19 . The spinal implant of  claim 16 , wherein the first and second arrays are provided on substantially the entire surface area of the first and second medial surfaces, with each of the individual ridge peaks of the first and second arrays being aligned with lines that emanate from the axis of rotation. 
     
     
         20 . The spinal implant of  claim 16 , wherein the first array is provided along a proximal portion of the first medial surface, and the second array is provided along a proximal portion of the second medial surface, which each of the individual ridge peaks of the first and second arrays being generally aligned with a longitudinal axis of the implant. 
     
     
         21 . The spinal implant of  claim 20 , wherein the first array is attached to a flexible member than enabled the first array to be displaced away from the second array in response to the application of a force that causes the relative rotational movement between the first and second implants to occur and the ridges of the first array to be moved from the ridge valleys of the second array. 
     
     
         22 . The spinal implant of  claim 16 , wherein the first and second arrays each comprises two semi-circular portions that partially encircle the axis of rotation and that are on opposite sides of the axis of rotation, with each of the individual ridge peaks of the first and second arrays being aligned with lines that emanate from the axis of rotation. 
     
     
         23 . The spinal implant of  claim 16 , wherein the first array is provided on a post element extending from a center portion of one of the first and second medial surfaces, and the second array is provided in an aperture provided on the other of the first and second medial surfaces, the post element and the aperture adapted to be coupled together. 
     
     
         24 . The spinal implant of  claim 23 , wherein each of the ridge peaks of the first array extend on the post element from a location near a proximal portion of the post element to a location near a distal portion of the post element, and each of the ridge peaks of the second array extend on an inner surface of the aperture from a location near the medial surface to a location deeper within the aperature. 
     
     
         25 . The spinal implant of  claim 1 , further comprising a rotational movement resistance mechanism adapted to resist rotational movement from a selected relative rotational position of the first intradiscal element in relation to the second intradiscal element. 
     
     
         26 . The spinal implant of  claim 25 , wherein the rotational movement resistance mechanism comprises a first borehole extending from a proximal surface of, to the medial surface of, one of the first and second intradiscal elements, and a second borehole extending from the medial surface of, and into, the other of the first and second intradiscal elements, the first and second boreholes being configured and aligned to receive an elongate member that extends from at least a portion of the first borehole and into at least a portion of the second borehole to affix the first intradiscal element in relation to the second intradiscal element in a first rotational orientation. 
     
     
         27 . The spinal implant of  claim 26 , wherein the rotational movement resistance mechanism further comprises a third borehole extending from the medial surface of, and into, the other of the first and second intradiscal elements, the first and third boreholes being configured and aligned to receive an elongate member that extends from at least a portion of the first borehole and into at least a portion of the second borehole to affix the first intradiscal element in relation to the second intradiscal element in a second rotational orientation that is different from the first rotational orientation. 
     
     
         28 . The spinal implant of  claim 26 , wherein the rotational movement resistance mechanism further comprises a third borehole extending from a proximal surface of, to the medial surface of, the one of the first and second intradiscal elements, the third and second boreholes being configured and aligned to receive an elongate member that extends from at least a portion of the third borehole and into at least a portion of the second borehole to affix the first intradiscal element in relation to the second intradiscal element in a second rotational orientation that is different from the first rotational orientation. 
     
     
         29 . The spinal implant of  claim 26 , wherein the first borehole has a widened cross-section, and is configured to engage the elongate element at different selected positions across a width of the borehole for select different rotational orientations between the first intradiscal element and the second intradiscal element. 
     
     
         30 . The spinal implant of  claim 26 , wherein the second borehole further extends entirely through, and to the outer surface of, the other of the first and second intradiscal elements, thus providing for the elongate element to also extend into a vertebra. 
     
     
         31 . The spinal implant of  claim 26 , wherein the elongate member comprises a screw. 
     
     
         32 . The spinal implant of  claim 1 , wherein each of the first and second intradiscal elements has formed therein at least one borehole adapted to receive a bone screw for affixing the intradiscal implant to an adjacent vertebra. 
     
     
         33 . The spinal implant of  claim 1 , wherein the first intradiscal element comprises a first proximal flange portion that extends generally perpendicularly to a longitudinal axis of the first intradiscal element, and a first borehole extending through the flange portion from a proximal face to a medial side, wherein the first proximal flange portion is configured to be positioned against a side aspect of a first vertebra for receipt of a bone screw through the first borehole in a trajectory that is generally parallel with to the longitudinal axis of the first intradiscal element. 
     
     
         34 . The spinal implant of  claim 32 , wherein:
 the first intradiscal element comprises a first borehole that extends from a first entry location provided in a first proximal surface portion located medial of a plane in which the first outer surface lies, the first borehole extending from the first entry location in a direction angled away from the first medial surface and to a first exit location provided on the first outer surface; and   the second intradiscal element comprises a second borehole that extends from a second entry location provided in a second proximal surface portion located medial of a plane in which the second outer surface lies, the second borehole extending from the second entry location in a direction angled away from the second medial surface and to a second exit location provided on the second outer surface.   
     
     
         35 . The spinal implant of  claim 34 , wherein the spinal implant and associate bones screws are adapted to not substantially protrude from the disc space when implanted in the disc space. 
     
     
         36 . The spinal implant of  claim 32 , further comprising at least one anti-backout mechanism that is adapted to prevent a bone screw from backing out of the at least one borehole after installation of the bone screw. 
     
     
         37 . The spinal implant of  claim 36 , wherein the anti-backout mechanism comprises a circular canted coil spring, and the at least one borehole comprises a circumferential chamber in which the canted coil spring is housed. 
     
     
         38 . The spinal implant of  claim 1 , wherein the first and second outer surfaces are ridged for secure engagement with the endplates of the adjacent vertebrae. 
     
     
         39 . The spinal implant of  claim 1 , wherein the first and second outer surfaces comprise spike elements for secure engagement with the endplates of the adjacent vertebrae. 
     
     
         40 . The spinal implant of  claim 1 , wherein the first intradiscal element comprises a first engagement mechanism adapted to be engaged by a distal tip of a first hand-held instrument, and the second intradiscal element comprises a second engagement mechanism adapted to be engaged by a distal tip of a second hand-held instrument, the first and second engagement mechanisms being configured to provide the relative rotational movement when acted upon by the first and second hand-held instrument in opposite directions. 
     
     
         41 . The spinal implant of  claim 40 , wherein at least one of the first and second engagement mechanisms comprises a threaded hole and elongate slot extending to each side of the threaded hole. 
     
     
         42 . The spinal implant of  claim 1 , wherein at least one of the first and second intradiscal elements is tapered from a proximal end to a distal end. 
     
     
         43 . The spinal implant of  claim 1 , wherein at least one of the first and second intradiscal elements is tapered from a first side to a second side. 
     
     
         44 . The spinal implant of  claim 33 , further comprising a cap configured to be placed on the first flange portion, the cap comprising holes formed in each side of the cap that align with the first borehole when the cap is placed on the first flange portion, the cap having a thickness in a medial portion selected to provide rotational pressure on a side of the vertebra to which the first flange portion is affixed. 
     
     
         45 . The spinal implant of  claim 1 , wherein the first and second intradiscal elements each have formed therein at least one fusion aperture extending from their respective outer surfaces to their respective medial surfaces, the at least one aperture in each of the first and second implants adapted to permit bone growth through the implant for spinal fusion. 
     
     
         46 . The spinal implant of  claim 45 , wherein at least one of the first and second intradiscal elements have at least one viewing aperture extending from a side surface of the intradiscal element to one of the at least one fusion aperture, the at least one viewing aperture being configured to provide a view of bone growth through the fusion aperture through use of an imaging machine. 
     
     
         47 . The spinal implant of  claim 1 , wherein the spinal implant is generally rectangular. 
     
     
         48 . The spinal implant of  claim 47 , wherein the spinal implant is sized and configured to extend laterally across a disc space, from one lateral aspect of the disc space to the opposite lateral aspect of the disc space. 
     
     
         49 . The spinal implant of  claim 1 , wherein the spinal implant has a cross-sectional shape in an axial plane that generally corresponds to the shape of the disc space. 
     
     
         50 . The spinal implant of  claim 49 , wherein the spinal implant is sized and configured to be inserted into the disc space using an anterior approach. 
     
     
         51 . A method of providing rotational adjustment of a spine, the method comprising:
 implanting in a disc space between adjacent vertebrae a spinal implant comprising a) a first intradiscal element having a first outer surface positioned adjacent an endplate of a first one of the adjacent vertebrae, and a first medial surface that is opposite the outer surface, b) a second intradiscal element comprising a second outer surface positioned adjacent an endplate of a second one of the adjacent vertebrae and comprising a second medial surface that is opposite the outer surface and positioned to generally face the first medial surface, and c) coupling mechanism that is associated with the first and second medial surfaces and that is adapted to provide relative rotational movement between the first and second intradiscal elements in a plane generally parallel with the first and second medial surfaces;   separately engaging each of first and second intradiscal elements and applying forces in opposite directions to provide the relative rotational movement to a selected rotational orientation of the first intradiscal element in relation to the second intradiscal element.   
     
     
         52 . The method of  claim 52 , wherein the coupling mechanism of the spinal implant provides for the relative rotational movement about an axis at a center portion of the first and second medial surfaces. 
     
     
         53 . The method of  claim 52 , wherein before implantation the first intradiscal element is assembled with the second intradiscal implant. 
     
     
         54 . The method of  claim 52 , wherein the method further comprises affixing each of the first and second intradiscal elements to respective adjacent vertebrae before the relative rotational movement is provided. 
     
     
         55 . The method of  claim 52 , wherein the spinal implant further comprises a rotational movement resistance mechanism adapted to resist rotational movement from a plurality of incremented relative rotational positions of the first intradiscal element in relation to the second intradiscal element. 
     
     
         56 . The method of  claim 52 , wherein the spinal implant further comprises a rotational movement resistance mechanism adapted to resist rotational movement from the selected rotational orientation. 
     
     
         57 . The method of  claim 52 , wherein the implant is implanted in the disc space using a lateral approach to the spine. 
     
     
         58 . The method of  claim 53 , wherein the first and second intradiscal elements are engaged using at least one insertion instrument accessed to the spine using the lateral approach.