Expandable interbody fusion cage with rotational insert

An intervertebral fusion cage, comprising:

• an inferior baseplate having an interior surface and an exterior surface, an upper end and a lower end opposite said upper end, a lock groove formed within said interior surface, and at least one slot extending from said upper end to a point intermediate said upper and lower ends;
• a superior baseplate having an interior surface and an exterior surface, an upper end and a lower end opposite said upper end of said superior baseplate, a lock groove formed within said interior surface of said superior baseplate, and at least one tab projecting from said exterior surface of said superior baseplate and extending from said upper end of said superior baseplate to said lower end of said exterior baseplate, said at least one slot of said inferior baseplate is sized and shaped to receive slidably said at least one tab of said superior baseplate when said inferior and superior baseplates are assembled with one another, said interior surfaces of said inferior and superior baseplates form a cavity when said inferior and superior baseplates are assembled with one another;
• wherein said interior surface of said inferior baseplate includes a first guide groove, and said interior surface of said superior baseplate includes a second guide groove, said first and second guide grooves are sized and shaped to guide said protuberances of said insert when said insert is rotated;
• a guide pin having a base and a peg projecting outwardly from said base, said base being coupled to said inferior and superior baseplates;
• and
• an insert having a first end and a second end opposite thereof, a pair of opposed side surfaces, a pair of diametrically opposed protuberances, each of which extends outwardly from one of said pair of side surfaces, a first aperture formed within said first end, and a second aperture formed within said second end, said second aperture is sized and shaped to receive said peg of said guide pin, said guide pin enables said insert to be rotated relative thereto, each of said protuberances of said insert being releasably engageable with a corresponding one of said lock grooves of said inferior and superior baseplates when said insert is rotated relative to said guide pin, whereby when said protuberances of said insert engage said lock grooves of said inferior and superior baseplates, said inferior and superior baseplates expand from a collapsed position, in which said inferior and superior baseplates are juxtaposed with one another, and an expanded position, in which said inferior and superior baseplates are diverged away from one another, said at least one tab of said superior baseplate is continuously engaged with said at least one slot of said inferior baseplate when said inferior and superior baseplates expand from their said collapsed position to their said expanded position, whereby said inferior and superior baseplates provide for parallel distraction when they expand from their said collapsed position to their said expanded position.