Stand-alone spinal cage

[0001] This original nonprovisional patent application claims the benefit of U.S. provisional application Ser. No. 61/302,088, filed Feb. 6, 2010 and entitled “Stand-Alone Spinal Cage,” and which is incorporated by reference herein.

[0002] Not applicable.

[0003] 1. Field of the Invention

[0004] The present invention relates to a spinal cage device. More specifically, the present invention is a stand-alone spinal cage designed to obviate the need for an accompanying anterior spinal plating systems.

[0005] 2. Description of the Related Art

[0006] Traditional spinal cages are often implanted with anterior plating to prevent movement of the spinal cage over time. The present invention is a stand-alone spinal cage that obviates the need to use anterior spinal plating systems.

[0007] The present invention is a spinal cage device for fusion of spinal vertebrae comprising a cage having a cavity defined by upper, lower, and side walls; a piston selectively insertable into the cavity through a side wall, the piston having at least one angled surface; at least one channel extending through at least one of the upper wall and the lower wall; at least one fastening member moveable within the at least one channel between a first disengaged position and a second engaged position; and wherein in second engaged position the at least one fastening member is held substantially stationary relative to the cage by contact with the piston. According to one aspect of the invention, the device includes a locking means for supplementing fixation of the piston to the cage by the internal screw(s). According to another aspect of the invention, the fastening members (e.g., nails or pins) of the device are porous to allow bone growth therethrough.

[0030] The present invention may be used in the cervical, lumbar, or thoracic regions of the spine. Some components of the embodiment described herein, such as the cage bodies, are preferably made of biocompatible OXPEKK, a poly-ether-ketone-ketone sold under the registered trademark of Oxford Performance Materials, Inc., Enfeld, Conn., USA. Alternative embodiments contemplate fabrication from biocompatible PEEK (poly-ether-ether-ketone). OXPEKK has approximately one-and-a-half to two times the compressive strength of PEEK, and therefore may be suited for constructing the cage body.

[0031] In addition to the foregoing, it should be noted that, while the embodiments described herein are solid bodies, they may also be formed as porous bodies, as described in U.S. application Ser. No. 612/952,788 (filed Nov. 23, 2010), entitled “Spinal Cage Device” and incorporated by reference herein.

[0032] While the terms “upper,” “lower,” “front,” “rear,” and similar terms are used throughout this document, it should be expressly understood that such are simply terms of convenience only to aid in description of the invention, and the orientation of the invention disclosed herein after during implantation is primarily within the surgeon's discretion.

[0033] A first embodiment 18 of the invention is shown in FIGS. 1-5. FIG. 1 is an assembly view of the first embodiment 18, which comprises a cage body 20 having upper and lower walls 22, 24 with ridges 26. Upper and lower walls 22, 24 partially define a cavity 28 of the cage body 20. Openings 30 through the upper and lower walls 22, 24 provide access to the cavity 28 to allow for bone growth thereinto from adjacent vertebrae. A piston 32 having upper and lower angled surfaces 34, 36 is insertable into the cavity 28 through a piston opening in the posterior sidewall of the cage body 20 to engage and drive nails 56. Piston screws 38 may thereafter be inserted through a piston faceplate 40 and secured to screw mounts 42 located in the cavity 28 near the posterior opening.

[0034] FIGS. 2A-2C show the cage body 20 is greater detail. Upper and lower rails 44, 46 extend along the length of, and protrude into the cavity 28 from, the upper and lower walls 22, 24, respectively. Screw mounts 42 are located near the posterior side of the cavity 28. Openings 30 through the upper wall 22 and lower wall 24 provide access to the cavity 28 to allow for bone growth thereinto from adjacent vertebrae. Cylindrical channels 31 are located between the two openings 30 and provide a cylindrical path through the upper wall 22 to the cavity 28. A pair of cylindrical channels (not shown) is disposed through the lower wall in similar fashion and aligned with the upper channels 31.

[0035] FIGS. 3A-3C show the piston 32 of the first embodiment in greater detail. The piston 32 has upper and lower angled planar surfaces 34, 36 approximately sixty degrees apart. Upper and lower grooves 48, 50 are formed longitudinally along the piston 32 and extend between the faceplate 40 and the upper and lower angled planar surfaces 34, 36. The grooves 48, 50 are alignable with, and during insertion guide the piston 32 along, upper and lower rails 44, 46 (see FIG. 2A), respectively, of the cage body 20. Shoulders 52 are formed in the piston body having a thickness T1. Engagement surfaces 53 are located between the shoulders 52 and the angled surfaces 34, 36

[0036] FIGS. 4A and 4B show a titanium nail 56 and bushing 58 of the first embodiment in greater detail. The nail 56 is generally cylindrical and has a nail head 60 of thickness T1 at a proximal end and tapers to a point 62 at the distal end. The nail head 60 has an angled portion 64 corresponding to the angled surfaces 34, 36 of the piston 32 (see FIGS. 3A-3C). The upper end 66 of the bushing 58 corresponds in shape to the upper wall 22 (see FIGS. 2A-2C) such that, when assembled, the bushing 58 is flush with the ridges 26 of the upper surface of the cage body 20 (see, e.g., FIG. 5A).

[0037] FIG. 5A and FIG. 5B are an isometric view and a top elevation view, respectively, of the first embodiment 18 with the nails 56 in a second engaged position. During implantation, the angled portions 60 of the nail heads 60 (see FIGS. 4A-4B) are contacted by and become flush with the angled surfaces 34, 36 of the piston 32 (see FIGS. 3A-3C), which, as the piston 32 is inserted further into the cavity 28, causes the nails 56 to move upwardly through the channels 31. In this manner, engagement of the upper angled surface 34 with the nail head 60 causes movement of the piston 32 into the cavity 28 to drive the nail 56 into the adjacent vertebra above the embodiment 18. Similarly, engagement of the lower angled surface 36 with nail heads causes movement of the piston 32 into the cavity 28 to drive lower nails (not shown) into the adjacent vertebra below the embodiment.

[0038] After complete insertion of the piston 32, each nail head 60 becomes flush with the corresponding engagement surface 53 to prevent the nail 56 from receding back into the cavity 28. This ensures fastening of the nail 56 to adjacent bone matter. The upper and lower rails 44, 46 (see FIGS. 2A, 2C) occupy the upper and lower grooves 48, 50, respectively, to ensure proper alignment of the piston 32 within the cavity 28. The ridged bushings 58 are fitted within the channels 31 in the annular space between the nail 56 and channel walls to facilitate slidable movement of the nail 56 therein. By threading the screws 38 through the faceplate 40 and the screw mounts 42, the piston 32 is drawn into the cavity 28 and secured to the cage body 20.

[0039] A second embodiment 118 of the invention, shown in FIGS. 6-10, comprises a cage body 120 having upper and lower walls 122, 124 with ridges 126. Upper and lower walls 122, 124 partially define a cavity 128 of the cage body 120. Openings 130 through the upper and lower walls 122, 124 provide access to the cavity 128 to allow for bone growth thereinto from adjacent vertebrae. A piston 132 having upper and lower angled planar surfaces 134, 136 is insertable into the cavity 128 through a piston opening in the posterior wall of the cage body 120. Screws 138 may thereafter be inserted through a piston faceplate 140 and secured to screw mounts 142 located in the cavity 128 proximal to the piston opening.

[0040] FIGS. 7A-7C show the cage body 120 of the second embodiment is greater detail. FIGS. 7A and 7C are bottom and top elevations, respectively, of the cage body 120. FIG. 7B is a rear elevation of the cage body 120. Upper and lower rails 144, 146 extend along the length of, and protrude into the cavity 128 from, the upper and lower walls 122, 124, respectively. Screw mounts 142 are located near the rear side of the cavity 128. Openings 130 through the upper and lower walls 122, 144 provide access to the cavity 128 to allow for bone growth thereinto from adjacent vertebrae. As shown in FIG. 7A, a channel 131 is located between the two openings 130 and provides a path through the lower wall 124 to the cavity. As shown in FIG. 7B, two channels 133 are located between the two openings 130 and provide a path through the upper wall 122 to the cavity 128.

[0041] FIGS. 8A and 8B show the piston 132 of the second embodiment 118 in greater detail. The piston 132 has upper and lower angled surfaces 134, 136 angled approximately sixty degrees apart. Upper and lower grooves 148, 150 are formed longitudinally along the piston 132 from the faceplate 140 to the upper and lower angled surfaces 134, 136. Upper and lower grooves 148, 150 are alignable with, and during insertion guide the piston 132 along, upper and lower rails 144, 146 (see FIG. 7B) of the cage body 120. Shoulders 152 are formed in the piston body having a thickness T2. Engagement surfaces 153 are located between the shoulders 152 and the angled surfaces 134, 136.

[0042] FIGS. 9A and 9B show a titanium pin 156 and bushing 158, respectively, of the second embodiment 118 in greater detail. Each pin 156 has an angled engagement surface 160 that corresponds to the angle of the upper and lower angled surfaces 134, 136 of the piston 132 (see FIG. 8B). Each pin 156 tapers to a wedge 162 at the distal end. The upper end 166 of the bushing 158 corresponds in shape to the upper wall 122 (see FIGS. 7A-7C) such that, when assembled, the bushing 158 is flush with the ridges 126 of the upper surface of the cage body 120 (see, e.g., FIG. 10).

[0043] FIG. 10 is a perspective view of the second embodiment 118 with the pins 156 in an engaged position. During implantation, the angled engagement surfaces 160 (see FIGS. 9A-9B) of the pins 156 are contacted by and become flush with the upper and lower angled surfaces 134, 136 of the piston 132, which, as the piston 132 is inserted further into the cavity 128, causes the pins 156 to move through the channels 131, 133 to an engaged position. In this manner, engagement of the upper and lower angled surfaces 134, 136 with the pins 156 causes movement of the piston 132 into the cavity 128 to drive the pins 156 into the adjacent vertebra. The piston screw heads are positioned anterior of the posterior surface of the faceplate 140.

[0044] After insertion of the piston 132 is complete, each engagement surface 160 is flush with the engagement surfaces 153 of the piston to prevent the pins 156 from receding back into the cavity 128 and ensuring fastening of the pins 156 with adjacent bone matter. The upper and lower rails 144, 146 (see FIG. 7B) occupy the upper and lower grooves 148, 150, respectively, of the piston 132 to ensure proper alignment of the piston 132 within the cavity 128. The ridged bushings 158 are fitted within the upper and lower channels 131, 133 in the annular space between the pin 156 and channel walls to facilitate movement between disengaged and engaged positions.

[0045] A third embodiment 218 of the invention, shown in FIGS. 11-15, comprises a cage body 220 having upper and lower walls 222, 224 with ridges 226. Upper and lower walls 222, 224 partially define a cavity 228. Openings 230 through the upper and lower wall 222, 224 and sidewalls provide access to the cavity 228 to allow for bone growth thereinto from adjacent vertebrae. Upper and lower lock openings 225, 227 are formed through the upper and lower walls, 222, 224, respectively proximal to a piston opening in the posterior wall of the cage body 220.

[0046] A piston 232 having upper and lower angled surfaces 234, 236 is insertable into the cavity 228 through the piston opening. A screw 238 may thereafter be inserted through a piston faceplate 240 and secured to a screw mount 242 located at the posterior of the cavity 228. A locking plate 280 having a closed end 283 and an opened end 284 defined by upper and lower fingers 286, 288 is rotatably attached to the faceplate 240 with a locking member screw 282.

[0047] FIGS. 12A-12C show the cage body 220 in greater detail. A screw mount 242 is located near the front of the cavity 228. Openings 230 through the upper wall 222 provide access to the cavity 228 to allow for bone growth thereinto from adjacent vertebrae. Rectangular channels 231, 233 are located between the openings 230 and provide paths through the upper wall 222 and lower wall 224 to the cavity. As shown in FIG. 12C, upper and lower rails 244, 246 extend along the length of, and protrude into the cavity 228 from, the upper and lower walls 222, 224, respectively.

[0048] FIGS. 13A-13C show the piston 232, piston screw 238, and locking plate 280 of the third embodiment in greater detail. The piston 232 has upper and lower angled surfaces 234, 236 angled approximately sixty degrees apart. Upper and lower grooves 248, 250 are formed longitudinally along the piston 232 between the faceplate 240 and the upper and lower angled surfaces 234, 236. Upper and lower grooves 248, 250 are alignable with, and during insertion guide the piston 232 along, upper and lower rails 244, 246 (see FIG. 12C) of the cage body 220. Shoulders 252 are formed in the piston body having a thickness T3. Engagement surfaces 253 are located between the shoulders 252 and the upper and lower angled surfaces 234, 236.

[0049] FIGS. 14A-14D show a titanium pin 256 and bushing 258, respectively, of the third embodiment 218 in greater detail. Each pin 256 has an angled engagement surface 260 that corresponds to the angle of the upper and lower angled surfaces 234, 236 of the piston 132 (see FIG. 13C). Each pin 256 tapers to an angled wedge 262 at the distal end. The upper end 266 of the bushing 258 corresponds in shape to the ridged upper surface (see FIGS. 7A-7C) such that, when assembled, the bushing 258 is flush with the ridges 226 of the cage body 220 (see, e.g., FIG. 10).

[0050] FIGS. 15A-15C disclose rear, front, and side elevations, respectively of the third embodiment 218. During implantation, the angled engagement surfaces 260 (see FIGS. 14A-14C) are contacted by and become flush with the upper and lower angled surfaces 234, 236 of the piston 232, which, as the piston 232 is inserted further into the cavity 228, causes the pins 256 to move upwardly through the channels 231, 233 to an engaged position. In this manner, engagement of the upper and lower angled surfaces 234, 236 with the pin 256 causes movement of the piston 232 into the cavity 228 to drive the pins 256 into the adjacent vertebra.

[0051] After insertion of the piston 232 is complete, each engagement surface 260 becomes flush with the engagement surface 253 to prevent the nail from receding back into the cavity 228 and ensuring fastening of the nail 256 with adjacent bone matter. The upper and lower rails 244, 246 (see FIGS. 12A, 12C) occupy the upper and lower grooves 248, 250, respectively, to ensure proper alignment of the piston 232 within the cavity 228. The ridged bushings 258 are fitted within the channels 231, 233 in the annular space between the titanium pin 256 and channel walls to facilitate movement and retain the pins 256 in the channels 231, 233.

[0052] Operation of the locking plate for this embodiment is identical to operation of the locking mechanism described hereafter with reference to the fourth embodiment

[0053] A fourth embodiment comprises a cage body 320, shown in FIGS. 16A-16C, comprises upper and lower walls 322, 324 with ridges 326. Upper and lower walls 322, 324 partially define a cavity 328. Openings 330 through the upper wall 322 provide access to the cavity 328 to allow for bone growth thereinto from adjacent vertebrae. Upper and lower lock openings 325, 327 are formed in the upper and lower walls 322, 324, respectively near the piston opening 328.

[0054] A piston 332 having upper and lower angled surfaces 334, 336 is insertable into the cavity 328. A screw 338 may thereafter be inserted through a piston faceplate 340 and secured to a screw mount located in the cavity 328. A locking plate 380 having a closed end 383 opened end 384 defined by upper and lower fingers 386, 388 is rotatably attached to the faceplate 340 with a screw 382. As shown in FIG. 16B, the fastening members of the fourth embodiment 318 comprises porous blades 356 with lateral passages 357 therethrough to allow bone growth.

[0055] FIG. 16B and FIG. 16C, which both depict the piston in an engaged position within the cage body 320, show the locking plate 380 in the unlocked and locked position, respectively. In the unlocked position, the screw 338 may be passed between the upper and lower fingers 386, 388, with the screw head accessible. Once the piston 382 is engaged with the cage body 320 to support the blades 356, the locking plate 380 is rotated around the locking plate screw 381 so that the lower finger 386 extends into the lower lock opening 325 and upper finger 386 covers the head of the piston screw 382. In this position, the locking plate 380 prevents “back out” of the piston screw 382 and piston 332, which assures engagement of the blades 356 with the adjacent vertebrae.

[0056] Although the embodiments of the present invention disclose titanium fastening members, alternative embodiments include stainless steel fastening members.

[0057] For each of the above-described embodiments, the upper and lower walls are at least substantially parallel. In alternative embodiments, however, the upper and lower walls may be angled relative to one another to correspond to curvature of the spine (e.g., to correspond to a lordotic curvature) at the targeted region of implantation. In such case, the front and rear sides will be of differing heights.

[0058] In addition to the nail and/or pins described hereinabove, alternative embodiments of the present invention contemplate a fastening member with a blade- or knife-like appearance, such as the porous blades shown in FIG. 17 and FIG. 20.

[0059] The present invention is described in terms of preferred illustrative embodiments of specifically described stand-alone spinal cages. Those skilled in the art will recognize that yet other alternative embodiments of such a device can be used in carrying out the present invention. Other aspects, features, and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.