System and method for forming a curved tunnel in bone

1. A method for attaching a ligament to a bone, the method comprising:

drilling, via a drill device, a U-shaped tunnel into the bone by entering into a first bone location and exiting through a second bone location, wherein the drill device comprises:

a drill bit guidance device comprising:

an elongated stationary outer tube extending along a first axis; and

an elongated inner tube configured to slidably move within the elongated stationary outer tube along the first axis and to exit from a distal end of the elongated stationary outer tube, wherein:

the elongated inner tube comprises a partially slotted distal end portion comprising a plurality of semi-cross-sectional slots extending perpendicular to the first axis; and

each of the semi-cross-sectional slots is configured to collapse inward in a direction of the slot when exiting the distal end of the elongated stationary outer tube, thereby curving the partially slotted distal end portion of the elongated inner tube;

a drive shaft disposed within the elongated inner tube; and

a flexible actuator rod arranged parallel to the drive shaft, wherein a distal end of the flexible actuator rod is attached to the partially slotted distal end portion of the elongated inner tube;

threading a suture through the U-shaped tunnel and through the ligament; and

attaching the ligament to the bone by tying the suture.

2. The method of claim 1 , wherein the drill bit guidance device further comprises:

a flexible shaft; and

a drill bit.

3. The method of claim 2 , wherein the flexible shaft comprises at least one of Nitinol wire and stainless-steel wire.

4. The method of claim 2 , wherein the elongated inner tube surrounds the drive shaft, the flexible actuator rod, and the flexible shaft.

5. The method of claim 2 , wherein:

the drill bit is attached to a distal end of the flexible shaft;

a distal end of the drive shaft is attached to a proximal end of the flexible shaft; and

the curving of the partially slotted distal end portion of the elongated inner tube is configured to curve the flexible shaft and to guide the attached drill bit along a curved path in drilling the U-shaped tunnel into the bone.

6. The method of claim 5 , wherein a radius of the curved path is configured to remain constant by maintaining constant a ratio of a length of the drive shaft to a length of the collapsed partially slotted distal end portion of the elongated inner tube.

7. The method of claim 1 , wherein:

the drill bit guidance device further comprises a universal grip, a handle block, a thrust assembly, and a linkage assembly;

the universal grip is attached to the handle block; and

the handle block comprises a first through-opening dimensioned to receive the elongated stationary outer tube.

8. The method of claim 7 , wherein:

the thrust assembly is pivotally linked to the handle block via the linkage assembly and comprises a shank chuck, a tube bushing, a thrust end cap, first and second thrust bushings, and an actuator slide;

the actuator slide comprises a second through-opening dimensioned to receive the elongated inner tube; and

a proximal end of the drive shaft is connected to the shank chuck.

9. The method of claim 7 , wherein:

a proximal end of the elongated inner tube, the proximal end of the drive shaft, and a proximal end of the flexible actuator rod are linked together via the linkage assembly; and

the linkage assembly is configured to maintain constant a ratio of a length of the drive shaft to a length of the collapsed partially slotted distal end portion of the elongated inner tube.

10. The method of claim 7 , wherein the linkage assembly comprises first and second vertical links configured to pivotally link the handle block to the elongated inner tube.

11. The method of claim 10 , wherein the linkage assembly further comprises first and second horizontal links configured to pivotally link the actuator slide to the first and second vertical links, respectively.

12. The method of claim 11 , the linkage assembly further comprises third and fourth horizontal links configured to pivotally link the actuator slide to the thrust end cap.

13. The method of claim 7 , wherein the thrust assembly is linked to the handle block via at least one of a gear mechanism and a cam mechanism.

14. The method of claim 1 , wherein each of the semi-cross-sectional slots is wider at a bottom portion thereof than at a top portion thereof.

15. The method of claim 1 , wherein the drill device further comprises:

a drill driver comprising a front opening configured to receive removable attachments, wherein the drill bit guidance device is configured to be removably attached to the front opening of the drill driver.