Spinal fusion device

1. A fusion device, comprising:

an actuator including a hollow shaft with an outer threaded surface;

a receiver disposed posterior to the actuator and including a first portion and a second portion disposed posterior to the first portion, the first portion having a first inner surface that is an inner threaded surface and configured to be coupled to the shaft of the actuator, the second portion having a second inner surface connected to the first inner surface;

a first plate and a second plate each slidably coupled to the actuator, the first and second plates being configured to move away from each other when the fusion device transitions from a first state to a second state;

a connector rotatably coupled to the receiver,

wherein each of the first and second plates is slidably coupled to the actuator and the connector.

2. The fusion device of claim 1 , wherein the shaft has a through hole, the shaft being configured to be inserted into the first inner surface of the receiver.

3. The fusion device of claim 1 , wherein the shaft has a through hole and the first state is a non-expanded state and the second state is an expanded state, and a longitudinal length of the receiver is in a range from 25% to 45% of a longitudinal length of the fusion device in the non-expanded state.

4. The fusion device of claim 1 , wherein the second portion of the receiver has the second inner surface with a size greater than that of the inner threaded surface of the first portion.

5. The fusion device of claim 1 , wherein the actuator further includes:

an anterior portion slidably coupled to the first plate and the second plate;

a posterior portion including the hollow shaft, a first wedge, and a second wedge, the first wedge and the second wedge being slidably coupled to the first plate and the second plate, respectively, the hollow shaft having a through hole;

a pair of side portions coupling the anterior portion and the posterior portion; and

an opening defined by the anterior portion, the posterior portion, and the pair of side portions, the opening being connected to the through hole of the hollow shaft.

6. The fusion device of claim 5 , wherein a first length of the opening in a longitudinal direction of the actuator is in a range from 15% to 30% of that of the actuator in the longitudinal direction, and

wherein a second length of the opening in a direction perpendicular to the longitudinal direction of the actuator is in a range from 50% to 70% of that of the actuator in the direction perpendicular to the longitudinal direction.

7. The fusion device of claim 5 , wherein the receiver is configured to be coupled to an injecting device to inject fusing material, and the through hole of the shaft is to deliver the fusing material therethrough.

8. The fusion device of claim 1 , wherein the receiver is configured to receive a set fastener to substantially fix a position of a posterior end of the hollow shaft, thereby locking the fusion device at a desired height.

9. The fusion device of claim 8 , wherein the set fastener has a threaded outer surface configured to be coupled to the inner threaded surface of the first surface of the first portion of the receiver.

10. The fusion device of claim 8 , wherein the connector is slidably coupled to the first plate and the second plate and includes a pair of side holes configured to receive a pair of prongs of an insertion tool.

11. The fusion device of claim 8 , further comprising one or more pins configured to keep the receiver within the connector by engaging with a neck of the receiver,

wherein the first plate includes a portion slidably coupled to a recess of the second plate, and

wherein the actuator includes a first upper portion and a lower portion each extending in an oblique direction with respect to a centerline of the actuator, the upper portion and the lower portion being slidably coupled to the first plate and the second plate, respectively.

12. An implant, comprising:

an actuator including a hollow shaft with an outer threaded surface;

a receiver disposed posterior to the actuator and including a first portion and a second portion disposed posterior to the first portion, the first portion having a first inner surface that is an inner threaded surface and configured to be coupled to the hollow shaft of the actuator, the second portion having a second inner surface connected to the first inner surface;

a connector rotatably coupled to the receiver; and

a first plate and a second plate each slidably coupled to the actuator and the connector, the first and second plates being configured to move away from each other when the fusion device transitions from a first state to a second state, wherein the shaft has a through hole for delivering material therethrough, and wherein the first state is a non-expanded state and the second state is an expanded state.

13. A method for using a fusion device, wherein the fusion device comprises an actuator and a receiver disposed posterior to the actuator, the actuator including a hollow shaft with an outer threaded surface, a channel, and an opening, the receiver including a first portion and a second portion disposed posterior to the first portion, the first portion having a first inner surface that is an inner threaded surface and configured to be coupled to the shaft of the actuator, the second portion having a second inner surface connected to the first inner surface, the method comprising:

inserting the fusion device in a first state into a treatment region;

transitioning the fusion device from the first state to a second state by inserting the hollow shaft of the actuator into the receiver;

injecting material through the channel of the fusion device to make the injected material flow out from the opening of the actuator; and

inserting a set fastener into the receiver to substantially fix a position of a posterior end of the inserted hollow shaft.

14. The method of claim 13 , wherein a longitudinal length of the receiver is in a range from 25% to 45% of a longitudinal length of the fusion device in the non-expanded state, and wherein the first state is a non-expanded state and the second state is an expanded state, wherein the material is fusing material.

15. The method of claim 13 , wherein a first length of the opening in a longitudinal direction of the actuator is in a range from 15% to 30% of that of the actuator in the longitudinal direction, and

wherein a second length of the opening in a direction perpendicular to the longitudinal direction of the actuator is in a range from 50% to 70% of that of the actuator in the direction perpendicular to the longitudinal direction.

16. The method of claim 13 , further comprising:

attaching the fusion device in the non-expanded state to an insertion tool.