Patent ID: 8267957
Filing Date: 2012-09-18
Classification: A61B

Abstract:
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.