A rod reducer including a housing defining an opening, a body member defining an opening and a slot, a shaft disposed through the opening of the housing and coupled to the opening of the body member, an anvil including a linkage extending therefrom, the linkage coupled to the body member and the anvil, a plurality of arm members, and a biasing element disposed between the body member and the anvil. A pin of the linkage is slidably disposed within the slot, and the biasing element is configured to bias the anvil distally with respect to the body member. Rotation of the shaft translates into linear movement, relative to the housing, of the shaft, the body member, and the anvil. The arm members are coupled to the housing and movable towards a parallel configuration as the anvil is advanced away from the housing to engage a bone screw.
1. A rod reducer comprising:
a housing defining an opening;
a body member defining a slot and cavities;
a shaft received through the opening of the housing and rotatably coupled with the body member;
first and second arm members coupled to the housing, the first and second arm members extending through the respective cavities of the body member, the first and second arm members transitionable between an approximated position and a spaced apart position;
a biasing member slidably coupled with the body member; and
an anvil coupled with the biasing member such that the anvil is biased distally, wherein rotation of the shaft causes axial displacement of the anvil, the axial displacement of the anvil directly transitioning the first and second arm members between the approximated and spaced apart positions.
2. The rod reducer according to claim 1 , wherein the biasing member is disposed between the anvil and the body member.
3. The rod reducer according to claim 1 , wherein the first and second arm members are movable relative to the housing about respective axes.
4. The rod reducer according to claim 1 , wherein the anvil defines cavities dimensioned to receive respective first and second arm members therethrough.
5. The rod reducer according to claim 1 , wherein the shaft includes an annular groove, and the body member includes pins dimensioned to be diametrically received in the annular groove of the shaft to rotatably couple the shaft with the body member.
6. The rod reducer according to claim 1 , wherein the anvil includes a linkage configured to receive the biasing member thereabout.
7. The rod reducer according to claim 6 , wherein the linkage and the anvil are monolithically formed.
8. The rod reducer according to claim 6 , wherein the linkage includes a pin protruding from a proximal portion of the linkage, the pin is dimensioned to be slidably received in the slot of the body member extending along a longitudinal axis defined by the shaft.
9. A rod reducer comprising:
a housing defining an opening;
a body member defining an opening and a slot, the body member movable relative to the housing;
a shaft disposed through the opening of the housing and coupled to the opening of the body member;
an anvil including a linkage extending therefrom, the linkage movably coupled to the body member, a pin of the linkage slidably disposed within the slot of the body member;
a biasing element disposed between the body member and the anvil, the biasing element configured to engage the anvil to bias the anvil distally; and
first and second arm members coupled to the housing, the first and second arm members configured to engage a bone screw, the first and second arm members movable towards a parallel configuration directly from advancement of the anvil away from the housing,
wherein rotation of the shaft translates the shaft relative to the housing.
10. The rod reducer according to claim 9 , wherein the biasing element is a compression spring.
11. The rod reducer according to claim 9 , wherein the biasing element applies between about 1 pound-force and about 30 pounds-force to the anvil.
12. The rod reducer according to claim 9 , wherein the pin of the linkage is configured to slide between a first end of the slot and a second end of the slot of the body member.
13. The rod reducer according to claim 12 , wherein the anvil and the biasing element are configured to transition the pin of the linkage from the second end of the slot to the first end of the slot upon proximal resistance exerted upon the anvil.
14. The rod reducer according to claim 9 , wherein the linkage is coupled to an aperture of the anvil.
15. The rod reducer according to claim 9 , wherein the biasing element is disposed about the linkage.
16. The rod reducer according to claim 9 , wherein the first and second arm members are pivotably coupled to the housing.
17. The rod reducer according to claim 9 , further comprising a receiving saddle disposed on the anvil, the receiving saddle configured to cooperatively engage a spinal rod.
18. The rod reducer according to claim 17 , wherein the receiving saddle includes an arch configured to engage with the spinal rod.