Compressor with extended ratchet bar feature
In one embodiment, a surgical instrument includes a first and second lever arms coupled by a first pivot. A ratchet bar is coupled to the first lever arm by a second pivot. The ratchet bar has a toothed portion extending from an interior face of the first lever arm and a paddle portion extending from an exterior face of the first lever arm. A catch is disposed at a proximate end of the second lever arm and arranged to engage teeth of the toothed portion of the ratchet bar. Engagement with the teeth couples the proximate ends of the first and second lever arms. The ratchet bar is further arranged to rotate about the second pivot in response to downward pressure upon the paddle. Depression of the paddle causes the teeth of disengage the catch, decoupling the first and second lever arms.
1. A surgical instrument comprising:
a first lever arm having distal and proximate ends;
a second lever arm having distal and proximate ends and coupled to the first lever arm by a first pivot;
a ratchet bar coupled to the first lever arm by a second pivot, the ratchet bar having a toothed portion extending from an interior face of the first lever arm and a paddle extending from an exterior face of the first lever arm, the paddle disposed at a downward angle with respect to the toothed portion of the ratchet bar such that when the surgical instrument is held in a substantially upright position, with the proximate ends of the first and second lever arms arranged upward, the paddle projects downward from the toothed portion and away from the proximate end of the first lever arm; and
a catch disposed on the second lever arm and arranged to engage teeth of the toothed portion of the ratchet bar, engagement with the teeth coupling the proximate ends of the first and second lever arms;
wherein the ratchet bar is formed with sufficient mass such that when the surgical instrument is held in the substantially upright position, gravitational force is sufficient to cause teeth of the toothed portion of the ratchet bar to engage the catch unless downward pressure is applied upon the paddle to overcome the gravitational force, and application of downward pressure upon the paddle to overcome the gravitational force causes the teeth to disengage the catch thereby decoupling the first and second lever arms, and
wherein the downward angle of the paddle causes the paddle to contact the exterior face of the first lever arm to limit the rotation of the ratchet bar about the second pivot and to maintain the ratchet bar in an orientation such that when the surgical instrument is held in the substantially upright position, gravity will cause the ratchet bar to fall back upon the catch absent application of downward pressure upon the paddle.
2. The surgical instrument of claim 1 wherein the first and second lever arms are sized to fit between a palm and fingers of a human hand, and wherein the paddle is located in a position where it may be depressed by one of a thumb and a finger of the human hand, to permit single-handed operation.
3. The surgical instrument of claim 1 wherein the toothed portion of the ratchet bar includes a weighted tip, the weighted tip being a protrusion of the ratchet bar that lacks teeth but that provides additional mass.
4. The surgical instrument of claim 1 wherein the paddle has a contoured upper face.
5. The surgical instrument of claim 4 wherein the contoured upper face includes a plurality of transverse grooves.
6. The surgical instrument of claim 1 wherein a flex spring is disposed between the first and second lever arms, the flex spring configured to hold the proximate ends of the first and second lever arms remote from each other when the compressor is in a resting state.
7. The surgical instrument of claim 1 wherein the ratchet bar is disposed in a cutout of the first lever arm.
8. The surgical instrument of claim 1 further comprising:
a first gripping extension arranged at the distal end of the first lever arm and having a substantially semi-circular contour; and
a second gripping extension arranged at the distal end of the second lever arm and having a substantially semi-circular contour.
9. The surgical instrument of claim 8 wherein the first and second gripping extensions are sized to engage cylindrical portions of bone anchors.
10. The surgical instrument of claim 1 wherein the surgical instrument is a compressor and the first and second distal ends are arranged to apply compressive force to a load.
11. The surgical instrument of claim 1 wherein the surgical instrument is a distractor and the first and second distal ends are arranged to apply separative force to a load.
12. A surgical instrument comprising:
a first lever arm having distal and proximate ends;
a second lever arm having distal and proximate ends and coupled to the first lever arm by a first pivot;
a cutout at the proximate end of the first lever arm extending from an interior face of the first lever arm to an exterior face of the first lever arm;
a ratchet bar extending through the cutout and coupled to the first lever arm by a second pivot, the ratchet bar having a toothed portion extending from the cutout at the interior face of the first lever arm and a paddle extending from the cutout at the exterior face of the first lever arm, the paddle disposed at a downward angle with respect to the toothed portion of the ratchet bar such that when the surgical instrument is held in a substantially upright position, with the proximate ends of the first and second lever arms arranged upward, the paddle projects downward from the toothed portion and away from the proximate end of the first lever arm; and
a catch disposed at the proximate end of the second lever arm and arranged to engage teeth of the toothed portion of the ratchet bar, engagement with the teeth coupling the proximate ends of the first and second lever arms;
wherein the ratchet bar is formed with sufficient mass such that when the surgical instrument is held in the substantially upright position, gravitational force is sufficient to cause teeth of the toothed portion of the ratchet bar to engage the catch unless downward pressure is applied upon the paddle to overcome the gravitational force, application of downward pressure upon the paddle to cause the teeth to disengage the catch thereby decoupling the first and second lever arms, and
wherein the downward angle of the paddle causes the paddle to contact the exterior face of the first lever arm to limit the rotation of the ratchet bar about the second pivot and to maintain the ratchet bar in an orientation such that when the surgical instrument is held in the substantially upright position, gravity will cause the ratchet bar to fall back upon the catch absent application of downward pressure upon the paddle.
13. The surgical instrument of claim 12 wherein the first and second lever arms are sized to fit between a palm and fingers of a human hand, and wherein the paddle is located in a position where it may be depressed by one of a thumb and a finger of the human hand, to permit single-handed operation.
14. The surgical instrument of claim 12 wherein the toothed portion of the ratchet bar includes a weighted tip, the weighted tip being a protrusion of the ratchet bar that lacks teeth but that provides additional mass.
15. The surgical instrument of claim 12 wherein the paddle has a contoured upper face.
16. The surgical instrument of claim 15 wherein the contoured upper face includes a plurality of transverse grooves.