Microfracture apparatuses and methods

1. An apparatus comprising:

a cannula having a first end, a second end, and a channel extending between the first end and the second end, the channel having a first transverse dimension between the first end and the second end and having a second transverse dimension at the second end that is smaller than the first transverse dimension, the channel tapering from the second transverse dimension to the first transverse dimension at a point closer to the second end than to the first end, the channel having a second end that is disposed at an angle relative to a first end of the channel; and

a penetrator having a distal end and a first transverse dimension, the penetrator configured to be disposed in the channel of the cannula such that the penetrator is movable between a retracted position and an extended position in which the distal end extends beyond the second end of the cannula by a penetration distance;

where the penetrator is configured to be moved from the retracted position to the extended position substantially without rotation of the penetrator to form in subchondral bone a microfracture.

2. The apparatus of claim 1 , where the first transverse dimension is substantially constant along a majority of the length of the channel.

3. The apparatus of claim 1 , where the cannula has a primary portion and a distal portion between the primary portion and the second end, the distal portion configured such that:

the channel has a third transverse dimension at a proximal end of the distal portion that is larger than the second transverse dimension.

4. The apparatus of claim 3 , where the third transverse dimension is substantially equal to the first transverse dimension.

5. The apparatus of claim 1 , where the distal portion of the cannula includes a plurality of curved segments.

6. The apparatus of claim 1 , where the penetration distance is at least 5 times greater than the first transverse dimension of the channel.

7. The apparatus of claim 6 , where the first transverse dimension is less than 1.2 millimeters (mm).

8. The apparatus of claim 7 , where the penetration distance is at least 5 millimeters (mm).

9. The apparatus of claim 1 , where the first transverse dimension is less than 1.2 millimeters (mm).

10. The apparatus of claim 9 , where the penetration distance is at least 5 millimeters (mm).

11. The apparatus of claim 9 , where the penetrator is configured to be moved from the retracted position to the extended position substantially without rotation of the penetrator to form in subchondral bone a microfracture having a depth of at least 5 mm.

12. The apparatus of claim 1 , where the penetrator is configured to be manually moved from the retracted position to the extended position.

13. The apparatus of claim 1 , where the penetrator has an enlarged head, and the penetration distance is limited by the enlarged head contacting the cannula.

14. The apparatus of claim 1 , where a coating is disposed on at least the penetration portion of the penetrator.

15. The apparatus of claim 1 , where the penetrator includes a primary portion and a penetration portion, the primary portion having a circular cross-section, the penetration portion disposed between the primary portion and the distal end, the penetration portion having a circular cross-section that is smaller than the circular cross-section of the primary portion.

16. The apparatus of claim 15 , where the distal end includes a pointed tip with a cross-sectional shape defined by a tip angle of 60 degrees or greater.

17. The apparatus of claim 16 , where the tip angle is bisected by a central longitudinal axis of the penetration portion, and the tip angle is greater than 90 degrees.

18. The apparatus of claim 1 , further comprising:

a penetrator removal tab coupled to the penetrator and configured to retract the penetrator relative to the cannula.

19. The apparatus of claim 18 , where:

the cannula includes a handle,

the penetrator includes a flange,

the penetrator removal tab includes an opening that is has at least one transverse dimension that is smaller than a transverse dimension of the flange; and

the penetrator removal tab is configured to be disposed between the handle and the flange with the penetrator extending through the opening.

20. The apparatus of claim 19 , where the penetrator removal tab includes a protrusion configured to extend toward the second end of the cannula and contact the handle to act as a fulcrum for pivoting the penetrator removal tab.