Patent ID: 7316686

Claim:
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.