Intervertebral expandable cage system and its instrument
An expandable cage ( 1 ) for maintaining a distance between two vertebras on a spine and providing fusion is disclosed. The expandable cage ( 1 ) comprises a horizontal axis, a front part with an upper arm ( 1.1 ), a lower arm ( 1.2 ), and shaft fixation sockets ( 1.7.1 and 1.7.2 ) located between the arms ( 1.1 and 1.2 ), and a hollow shaft ( 2 ) with graft holes ( 2.4 ). The shaft ( 2 ) is placed parallel to the horizontal axis and partially inside the shaft fixation sockets ( 1.7.1 and 1.7.2 ). The cage ( 1 ) is expanded vertically by rotating the shaft ( 2 ) 90 degrees with an instrument, thus further separating vertically the upper arm ( 1.1 ) and the lower arm ( 1.2 ).
1. An expandable cage ( 1 ) system comprising:
a vertically expandable front part,
a back part,
a lower surface,
an upper surface,
an open position,
a closed position,
a cage length measured from the back part to the front part,
an upper arm ( 1 . 1 ) located at the front part,
a lower arm ( 1 . 2 ) located at the front part,
an expandable cage cut ( 1 . 3 ) located between the upper arm ( 1 . 1 ) and the lower arm ( 1 . 2 ),
an outer socket ( 1 . 7 . 1 ) located inside the expandable cage cut ( 1 . 3 ),
an inner socket ( 1 . 7 . 2 ) located inside the outer socket ( 1 . 7 . 1 ),
lower and upper teeth ( 1 . 4 ) respectively located at the lower and the upper surfaces,
an instrument hollow ( 1 . 5 ) located at the back part,
a threaded instrument hole ( 1 . 6 ) located at the back part,
a central space ( 1 . 8 ),
a horizontal axis extending from the back part to the front part, and
a shaft ( 2 ) extending from the back part to the front part, the shaft ( 2 ) being restricted to a single 90° rotation movement around the horizontal axis and having:
a shaft length being substantially the same as the cage length;
a frontal expansion end ( 2 . 1 ) placed at the front part in the outer socket ( 1 . 7 . 1 );
a cornered back end ( 2 . 2 ) placed at the back part; and
a shaft body ( 2 . 3 ) located between the frontal expansion end ( 2 . 1 ) and the cornered back end ( 2 . 2 ), wherein
a. at the closed position, the frontal expansion end ( 2 . 1 ) of the shaft ( 2 ) sits in the outer socket ( 1 . 7 . 1 ),
b. during the 90° rotation movement of the shaft ( 2 ), the frontal expansion end ( 2 . 1 ) slides from the outer socket ( 1 . 7 . 1 ) into the inner socket ( 1 . 7 . 2 ), and
c. after the 90° rotation movement of the shaft ( 2 ), the system irreversibly reaches the open position, the upper arm ( 1 . 1 ) and the lower arm ( 1 . 2 ) are further separated, and the frontal expansion end ( 2 . 1 ) is locked in the inner socket ( 1 . 7 . 2 ) to prevent accidental movement of the shaft ( 2 ).
2. An expandable cage ( 1 ) system according to claim 1 , wherein the shaft ( 2 ) has no further rotational moving capability around the horizontal axis after the single 90° rotation movement configured for the system to irreversibly transit from the closed position to the open position.
3. An expandable cage ( 1 ) system according to claim 1 , wherein
a. the back end ( 2 . 2 ) and the shaft body ( 2 . 3 ) are hollow,
b. the shaft body ( 2 . 3 ) further comprises at least one hole ( 2 . 4 ), and
c. the back end ( 2 . 2 ) further comprises a graft filling hole ( 2 . 5 ) configured for a bone graft to be injected into the shaft ( 2 ) after the system is inserted between vertebras.
4. An expandable cage ( 1 ) system according to claim 1 , wherein the back end ( 2 . 2 ) of the shaft ( 2 ) is square or hexagonal or octagonal and the frontal expansion end ( 2 . 1 ) is rectangular prism-shaped.
5. An expandable cage ( 1 ) system according to claim 1 , wherein
a height of the inner socket ( 1 . 7 . 2 ) is greater than a height of the outer socket ( 1 . 7 . 1 ), and
a width of the frontal expansion end ( 2 . 1 ) of the shaft ( 2 ) at the closed position is greater than a height of the frontal expansion end ( 2 . 1 ) and the height of the inner socket ( 1 . 7 . 2 ).