Rod inserter and insertion tube
View Patent ↗A spinal rod insertion instrument includes a hollow, monolithic body having a proximal end and a distal end. The body defines a passageway that extends along a first axis between the proximal and distal ends. The distal end includes first and second arms defining a slot therebetween. The first and second arms are configured to releasably retain a spinal rod therebetween. Also provided is a method of securing a spinal rod to a coupling element attached with a pedicle screw.
1. A spinal rod insertion instrument comprising:
a hollow, monolithic body having a proximal end and a distal end, the body defining a passageway that extends along a first axis between the proximal and distal ends, the distal end including first and second arms defining a slot therebetween, the slot defining a retaining aperture extending along a second axis perpendicular to the first axis, the retaining aperture having a substantially circular cross-section in a plane perpendicular to the second axis, the slot further defining a channel extending proximally from the retaining aperture, the channel being configured to widen and return to a resting state;
wherein each arm includes a protrusion defined by a point on the circular cross-section, the protrusions facing each other, wherein, when the instrument is in the resting state, the retaining aperture defines an inner diameter of the circular cross-section and the protrusions are separated by a first dimension perpendicular to the first axis, the inner diameter being larger than the first dimension such that the first and second arms releasably retain a spinal rod therebetween in a fixed position along the first axis when the spinal rod is located in the retaining aperture, and
wherein a cross-section of the body in a plane perpendicular to the first axis forms a complete circle at a point along the first axis, wherein the first and second arms include chamfered edges at a distal end of the slot, the chamfered edges being separated by a second dimension perpendicular to the first axis, and wherein, when the instrument is in the resting state, the second dimension is larger than the inner diameter.
2. The instrument of claim 1 , wherein the body is substantially cylindrical.
3. The instrument of claim 1 , wherein the circular cross-section of the retaining aperture defines an edge that substantially matches a circumference of a spinal rod when a spinal rod is disposed therein.
4. The instrument of claim 1 , wherein the passageway of the body has a distal portion and a proximal portion, the distal portion having an inner diameter larger than an inner diameter of the proximal portion.
5. The instrument of claim 4 , wherein the body further includes an annular shoulder disposed at a junction between the distal and proximal portions of the passageway.
6. The instrument of claim 1 , wherein a proximal end of the channel defines a circular cross-section in a plane perpendicular to the second axis, a diameter of the circular cross-section being greater than a width of the channel.
7. A spinal rod insertion kit comprising:
the instrument of claim 1 , and
a driving tool for inserting a fastener.
8. A spinal rod insertion kit comprising:
a plurality of instruments as claimed in claim 1 , each having a retaining aperture of a different size.
9. A spinal rod insertion kit comprising:
the instrument of claim 1 ,
a spinal rod, and
a screw assembly including a pedicle screw, a coupling element, and a fastener.
10. The kit of claim 9 , further comprising a driving tool for inserting the fastener.
11. A spinal rod insertion kit comprising:
the instrument of claim 1 , and
a spinal rod, wherein the circular cross-section of the retaining aperture defines an edge that substantially matches a circumference of the spinal rod when the spinal rod is disposed therein.
12. The spinal rod insertion kit of claim 11 , wherein the spinal rod defines a rod diameter being greater than the first dimension, less than the second dimension, and substantially the same as the inner diameter of the retaining aperture.
13. A method of securing a spinal rod to a coupling element attached with a pedicle screw, the method comprising:
releasably retaining a spinal rod in a fixed position along a first axis within a slot defined between first and second arms at a distal end of a hollow, monolithic body of an insertion instrument, the body defining a passageway that extends along a first axis between a proximal end and the distal end, the retaining aperture extending along a second axis perpendicular to the first axis, the retaining aperture having a substantially circular cross-section in a plane perpendicular to the second axis, the slot further defining a channel extending proximally from the retaining aperture, the channel being configured to widen and return to a resting state; wherein each arm includes a protrusion defined by a point on the circular cross-section, the protrusions facing each other, wherein, when the instrument is in the resting state, the retaining aperture defines an inner diameter of the circular cross-section and the protrusions are separated by a first dimension perpendicular to the first axis, the inner diameter being larger than the first dimension such that the first and second arms releasably retain a spinal rod therebetween in a fixed position along the first axis when the spinal rod is located in the retaining aperture wherein a cross-section of the body in a plane perpendicular to the first axis forms a complete circle at a point along the first axis, wherein the first and second arms include chamfered edges at a distal end of the slot, the chamfered edges being separated by a second dimension perpendicular to the first axis, and wherein, when the instrument is in the resting state, the second dimension is larger than the inner diameter; and
contacting the insertion instrument with a coupling element of a screw assembly including a pedicle screw to align the spinal rod within a channel of the coupling element.
14. The method of claim 13 , wherein the step of releasably retaining the spinal rod between the first and second arms includes releasably securing the spinal rod in a fixed position within a retaining aperture.
15. The method of claim 13 , further comprising engaging a fastener within the channel of the coupling element to secure the spinal rod between the coupling element and the fastener.
16. The method of claim 15 , wherein the step of engaging the fastener within the channel of the coupling element includes inserting a driving tool through the passageway of the body.
17. The method of claim 16 , wherein the fastener is removably loaded onto the driver tool prior to engaging the fastener with the channel of the coupling element.