Unidirectional dynamic interbody fusion device and method of use

An interbody fusion device, the device comprising:

• a base member including a top surface having a plurality of teeth, a bottom surface having a plurality of teeth, a passageway, at least one opening, a lip and a notch;
• a top member including a top surface having a plurality of teeth, a bottom surface having a plurality of teeth, and a protrusion for detachably coupling with the lip of the base member;
• and
• a threaded rod and a support ring for moving the top member relative to the base member, wherein the threaded rod moveably couples the base member and the top member, and wherein the support ring is configured to engage the notch of the base member to couple the threaded rod to the base member to maintain the superior and inferior position of the threaded rod,
• wherein the threaded rod includes a gear rotatable therewith,
• wherein the passageway is parallel to a longitudinal axis of the base member and terminates at the at least one opening to communicate with the gear, wherein the lip is operable to engage the protrusion to prevent the top member from disengaging from the base member.

A surgical method for maintaining a space between two vertebral bodies in a spine, comprising:

• a body member including a top surface having a plurality of teeth, a bottom surface having a plurality of teeth, and at least one opening with a notch;
• at least one side member including a top surface having a plurality of teeth and a bottom surface having a plurality of teeth;
• and
• a threaded rod and a support ring, the threaded rod including a rotatable gear and internal threads configured to threadably engage a screw for translating the at least one side member relative to the body member, wherein the support ring engages the notch in the body member to connect the threaded rod to the body member to maintain the position of the threaded rod wherein the threaded rod is transverse to a longitudinal axis of the medical device,
• inserting and coupling an expansion tool into another opening parallel to the longitudinal axis within the medical device to communicate with the rotatable gear;
• slidingly inserting the medical device into a space between two vertebral bodies;
• and
• rotating the expansion tool to move the at least one side member in a direction relative to the body member.