Devices and methods for implanting fusion cages
First Claim
1. A fusion device insertable in the disc space between an upper vertebra and a lower vertebra, the device comprising:
- a body extending between a leading end and a trailing end, said body having a wall defining a hollow interior, said wall having upper and lower bearing surfaces separated by a height that is selected to maintain the desired spacing between the upper vertebra and the lower vertebra, said height being tapered from a first height at said leading end to a second height at said trailing end to restore lordosis when the device is inserted in the disc space, said height between said upper and lower bearing surface being selected so that said body contacts the cortical bone of a substantially intact upper vertebral endplate and the cortical bone of a substantially intact lower vertebral endplate when the device is inserted in an unreamed disc space, said body including one or more threads extending outwardly from said upper and lower bearing surfaces, wherein said one or more threads are engageable to the cortical bone of the adjacent vertebral endplate with said upper and lower bearing surfaces contacting the adjacent vertebral endplates and said threads increase in depth from said leading end to said trailing end.
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Abstract
Methods and instrumentation for spinal interbody fusion are disclosed. The instruments and methods are particularly adapted for interbody fusion in an unreamed disc space. One instrument is a distractor assembly including a first distractor and a second distractor configured to be inserted in side-by-side relation in the disc space. Fusion cages adapted for insertion into an unreamed disc space are provided to enhance load distribution between adjacent vertebral bodies and lateral stability of the spinal column. The fusion cages may be inserted after distracting the disc space with the distractor assembly. Instruments for preparing the disc space through the inserted fusion cages or for use with the distractor assembly are also provided.
120 Citations
46 Claims
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1. A fusion device insertable in the disc space between an upper vertebra and a lower vertebra, the device comprising:
a body extending between a leading end and a trailing end, said body having a wall defining a hollow interior, said wall having upper and lower bearing surfaces separated by a height that is selected to maintain the desired spacing between the upper vertebra and the lower vertebra, said height being tapered from a first height at said leading end to a second height at said trailing end to restore lordosis when the device is inserted in the disc space, said height between said upper and lower bearing surface being selected so that said body contacts the cortical bone of a substantially intact upper vertebral endplate and the cortical bone of a substantially intact lower vertebral endplate when the device is inserted in an unreamed disc space, said body including one or more threads extending outwardly from said upper and lower bearing surfaces, wherein said one or more threads are engageable to the cortical bone of the adjacent vertebral endplate with said upper and lower bearing surfaces contacting the adjacent vertebral endplates and said threads increase in depth from said leading end to said trailing end. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A fusion device insertable in the disc space between an upper vertebra and a lower vertebra, the device comprising:
a body extending between a leading end and a trailing end, said body having a wall defining a hollow interior, said wall having upper and lower bearing surfaces separated by a height that is selected to maintain the desired spacing between the upper vertebra and the lower vertebra, said height being tapered from a first height at said leading end to a second height at said trailing end to restore lordosis when the device is inserted in the disc space, said height between said upper and lower bearing surface being selected so that said body contacts the cortical bone of a substantially intact upper vertebral endplate and the cortical bone of a substantially intact lower vertebral endplate when the device is inserted in an unreamed disc space, said body including one or more threads extending outwardly from said upper and lower bearing surfaces, wherein said body includes an end nose at said leading end. - View Dependent Claims (12, 13)
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14. A combination, comprising:
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a distractor having a body portion with an upper surface and a lower surface and a distraction height therebetween, said distraction height corresponding to the desired disc space height between adjacent vertebral endplates; and a fusion cage having a body including one or more threads extending outwardly therefrom, said body extending between a leading end and a trailing end of said fusion cage, said body having an upper bearing surface and a lower bearing surface separated by a height that increases from said leading end to said trailing end along said body, said height at said leading end of said fusion cage being the same as said distraction height of said distractor, wherein said body portion of said fusion cage engages the intact adjacent vertebral endplates when said cage is inserted in the disc space, wherein said threads are configured to engage the cortical bone of the adjacent vertebral endplates and advance said fusion cage into the disc space as it is threaded therein and said threads increase in depth from said leading end to said trailing end. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A combination, comprising:
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a distractor having a body portion with an upper surface and a lower surface and a distraction height therebetween, said distraction height corresponding to the desired disc space height between adjacent vertebral endplates; and a fusion cage having a body including one or more threads extending outwardly therefrom, said body extending between a leading end and a trailing end of said fusion cage, said body having an upper bearing surface and a lower bearing surface separated by a height that increase from said leading end to said trailing end along said body, said height at said leading end of said fusion cage being the same as said distraction height of said distractor, wherein said body portion of said fusion cage engages the intact adjacent vertebral endplates when said cage is inserted in the disc space, wherein said body of said fusion cage includes an end nose at said leading end. - View Dependent Claims (26, 27)
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28. A fusion device insertable in the disc space between an upper vertebra and a lower vertebra, the device comprising:
a body extending between a leading end and a trailing end, said body having a wall defining a hollow interior, said wall having upper and lower bearing surfaces separated by a height, said body including at least one thread extending from said upper and lower bearing surfaces, wherein when implanted into the disc space with the disc space in an unreamed condition said body functions to contact cortical bone of a substantially intact upper vertebral endplate and cortical bone of a substantially intact lower vertebral endplate with said at least one thread engaged in cortical bone of each of the upper and lower vertebral endplates, said body maintaining a desired spacing between the upper vertebra and the lower vertebra when implanted, wherein said at least one thread increases in depth from said leading end to said trailing end. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A fusion device insertable in the disc space between an upper vertebra and a lower vertebra, the device comprising:
a body extending between a leading end and a trailing end, said body having a wall defining a hollow interior, said wall having upper and lower bearing surfaces separated by a height, said body including at least one thread extending from said upper and lower bearing surfaces, wherein when implanted into the disc space with the disc space in an unreamed condition said body functions to contact cortical bone of a substantially intact upper vertebral endplate and cortical bone of a substantially intact lower vertebral endplates with said at least one thread engaged in cortical bone of each of the upper and lower vertebral endplates, said body maintaining a desired spacing between the upper vertebra and the lower vertebra when implanted, wherein said body includes an end nose at said leading end. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46)
Specification