A surgical tool includes a pair of pivotally coupled operating handles and working distal ends connected thereto configured to engage bone fixation elements. A toothed ratchet member is arranged across the handles and includes a first and second tooth rack. The first tooth rack includes a plurality of teeth angled in a first direction and the second tooth rack includes a plurality of teeth angled in a second direction. The ratchet member is rotatable with respect to the handles to selectively present the first or second tooth rack to a pawl disposed on one of the handles. The handles are operable for closing or spreading movement via selective engagement of the pawl with the first or second tooth rack, which correspondingly closes or spreads the working distal ends. A method for operating the tool is also disclosed.
1. A surgical tool comprising:
a body including a distal working portion and a proximal operating portion pivotally coupled to the working portion;
the working portion including a pair of elongated working members each having a distal end configured for engaging a fixation element securable to a bone segment, the working members movably coupled together and configured for motion in an opening distraction direction and a closing compression direction with respect to each other;
the operating portion including a pair of elongated handles pivotally coupled together and configured for opening and closing movement with respect to each other, the operating portion being configured so that moving the handles apart in an opening direction moves the working members together in the closing compression direction, and moving the handles together in a closing direction handles moves the working members apart in the opening distraction direction;
an elongated toothed ratchet member arranged across the handles and pivotally coupled to one of the handles, the ratchet member comprises an outer ratchet bar and an inner control rod disposed inside an axially elongated cavity formed in the ratchet bar, the ratchet bar being slidable between unlocked and locked positions with respect to the control rod, the ratchet member being engageable with a pawl disposed on the other handle, the ratchet member being rotatable between two different operating positions;
wherein when the ratchet member is in a first operating position engaged with the pawl, the handles are movable in the closing direction and prevented from movement in the opening direction by the ratchet bar, and
wherein when the ratchet member is in a second operating position engaged with the pawl, the handles are movable in the opening direction and prevented from movement in the closing direction by the ratchet bar.
2. The surgical tool of claim 1 , wherein the ratchet member includes first and second tooth racks disposed on opposite sides of the ratchet member, the tooth racks being selectively and alternatingly engageable with the pawl by rotating the ratchet member between the first and second operating positions.
3. The surgical tool of claim 1 further comprising a locking knob rotatably disposed on the control rod, the knob being selectively engageable with one end of the ratchet bar to prevent sliding the ratchet bar on the control rod.
4. The surgical tool of claim 1 wherein one of the ratchet bar and control rod includes a locking projection engageable with a locking recess disposed on the other remaining one of the ratchet bar and control rod, the projection and recess being mutually configured to prevent rotation of the ratchet bar with respect to the control rod when engaged.
5. The surgical tool of claim 4 , further comprising a spring acting between the locking knob and ratchet bar, the spring operable to bias the locking projection and recess into engagement.
6. The surgical tool of claim 1 , further comprising a biasing member attached to one of the handles and urging one end of the ratchet member against the pawl.
7. The surgical tool of claim 1 , further comprising a motion control brace coupling the working members together, the brace being operable to maintain the working members in substantially parallel relationship to each other when moving between the opening distraction direction and the closing compression direction.
8. The surgical tool of claim 1 , wherein the ratchet member includes a first tooth rack comprising a plurality of teeth angled in a first direction and a second gear rack comprising a plurality of teeth angled in a second direction opposite the first direction.