Unidirectional dynamic interbody fusion device and method of use

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

• obtaining a movable interbody implant, the implant comprising:
• a top member having a superior bone-engaging side and a threaded opening;
• a base member configured to be received by the top member, the base member having an expansion tool opening, an inferior bone-engaging side and an open cavity in communication with the threaded opening of the top member and expansion tool opening;
• an expansion member positioned within the open cavity for rotation about an axis extending transverse to the superior and inferior bone-engaging sides, the expansion member having a threaded portion threadably engaged with the threaded opening and a central bore to maintain an opening through the threaded opening in the superior bone-engaging side through the open cavity in the inferior bone-engaging side, and
• a support ring coupled to the base member within the open cavity, the support ring configured to retain the expansion member within the base member in a fixed position along the axis relative to the inferior bone-engaging side,
• wherein rotation of the expansion member moves the top member relative to the base member along the axis, while the support ring maintains the fixed position of the expansion member relative to the inferior bone-engaging side along the axis.

A surgical method for maintain a space between two bones, the method comprising:

• obtaining a movable surgical implant, the implant comprising:
• a top member having a first bone-engaging side and a threaded opening;
• a base member received by the top member, the base member having a second bone-engaging side and an open cavity in communication with the threaded opening of the top member;
• an expansion member secured within the open cavity for rotation about an axis extending transverse to the first and second bone-engaging sides, the expansion member having a threaded portion threadably engaged with the threaded opening and a central bore to maintain an opening through the threaded opening in the first bone-engaging side through the open cavity in the second bone-engaging side, and
• a support ring fixed to the base member within the open cavity, the support ring configured to secure the expansion member within the base member in a fixed position along the axis relative to the second bone-engaging side,
• wherein rotation of the expansion member translates the top member relative to the base member along the axis;
• and
• wherein the support ring is configured to be inserted into a notch in the base member within the open cavity to retain the expansion member within the base member.

A method for maintain a space between two bones, the method comprising:

• obtaining a surgical implant, the implant comprising:
• a top member having a first bone-engaging surface and a threaded opening;
• a base member received by the top member, the base member having a second bone-engaging surface and an open cavity aligned with the threaded opening of the top member;
• an expansion member disposed within the open cavity for rotation about an axis, the expansion member having a threaded portion threadably engaged with the threaded opening and a central bore to maintain an opening through the threaded opening in the first bone-engaging surface through the open cavity in the second bone-engaging surface;
• and
• a support ring coupled to the base member within the open cavity, the support ring sized to retain the expansion member within the base member in a position along the axis relative to the second bone-engaging surface,
• wherein rotation of the expansion member translates the first bone-engaging surface away from the second bone-engaging surface, while the support ring maintains the fixed position of the expansion member relative to the second bone-engaging surface.