Flexible spinal driver or drill with a malleable core, and/or fixed core radius
The improvement is a spinal instrument (preferably, a bone screw driver) having a flexible shaft comprising a plurality of interlocking segments carried on a malleable core rod. The flexible shaft allows a screwdriver handle to be perfectly in-line with the cage inserter if desired, while still taking advantage of the tactile feel and torque transmission of the flex segment in its bent position. Accordingly, a surgeon can limit the amount of retraction and keep the driver handle close to the inserter without having to overcome the forces of the flexible segments' natural straight configuration.
1. A flexible spinal instrument comprising:
a) a proximal portion adapted for connection to a handle or a drill,
b) an intermediate shaft comprising:
i) a plurality of interlocking segments, each segment having a throughhole, and
ii) a malleable rod extending through the throughhole of each segment, and
c) a distal portion having a solid, lumen-free working tip,
d) a bone screw attached to the working tip,
wherein the working tip is attached only to a distalmost interlocking segment,
wherein the working tip has a diameter that is less than a diameter of the distalmost interlocking segment,
wherein the malleable rod has a pre-determined pre-bent angle in its unloaded condition, thereby pre-determining the trajectory of the tip and facilitating the appropriate and desired insertion angle of a screw into a drill guide without increasing the amount of tissue retraction,
wherein the malleable rod is the only component extending through the throughhole of each segment.
2. The spinal instrument of claim 1 wherein the proximal portion comprises a rigid tube, and the flexible rod extends into the rigid tube.
3. The spinal instrument of claim 1 wherein the proximal portion comprises a solid rigid rod.
4. The spinal instrument of claim 1 wherein the distal portion is connected to a distalmost interlocking segment.
5. The spinal instrument of claim 1 wherein the malleable rod comprises a polymer.
6. The spinal instrument of claim 1 wherein the malleable rod comprises a memory metal.
7. The spinal instrument of claim 6 wherein the memory metal rod is connected to the distal portion of the spinal instrument.
8. The spinal instrument of claim 6 wherein the memory metal rod is connected to the distal and proximal portions of the spinal instrument.
9. The spinal instrument of claim 6 wherein the memory metal rod is connected to neither of the distal and proximal portions of the spinal instrument.
10. The spinal instrument of claim 1 wherein the malleable rod floats with the plurality of interlocking segments.
11. The spinal instrument of claim 1 wherein the malleable rod has a distal bearing surface.
12. The spinal instrument of claim 1 wherein the working tip is adapted to drill a hole.
13. The spinal instrument of claim 1 wherein the instrument is a screwdriver.
14. The spinal instrument of claim 1 having a first substantially linear configuration and a second deformed configuration, wherein the second deformed configuration allows rotation of the shaft and an application of force along an axis of the working tip.
15. The spinal instrument of claim 1 wherein the distalmost of the interlocking segments has a transverse throughhole.
16. The spinal instrument of claim 1 wherein the working tip tapers distally.