Flexible surgical devices
A medical device comprises a tube including a wall with a plurality of slits oriented generally transverse to a longitudinal axis of the tube and defined by opposing surfaces. A pair of force transmission elements is actuatable to alter the tube between a flexible state and a stiffened state. A first force transmission element of the pair is coupled to an opposite side of the tube from the second force transmission element of the pair. The surgical device also includes a plurality of routing members coupled to the wall of the tube and configured to receive and route the force transmission elements along a length of the tube while permitting the length of the tube to flex and compress. Equal tension forces applied to the pair of force transmission elements compress the tube to create the stiffened state by deforming regions of the tube disposed between the plurality of slits.
1. A medical device comprising:
a tube including a wall with a plurality of slits oriented generally transverse to a longitudinal axis of the tube, wherein each slit of the plurality of slits is defined by opposing surfaces, the tube including a proximal segment and a distal segment;
a pair of force transmission elements coupled to the tube and actuatable to alter the tube between a flexible state and a stiffened state, wherein a first force transmission element of the pair is coupled to an opposite side of the tube from a second force transmission element of the pair; and
a plurality of routing members, each routing member coupled to the wall of the tube, the routing members configured to receive and route the force transmission elements along a length of the tube while permitting the length of the tube to flex and compress,
wherein equal tension forces applied to the pair of force transmission elements compress the tube to create the stiffened state by deforming regions of the tube disposed between the plurality of slits.
2. The medical device of claim 1 wherein the tube in the stiffened state is straightened and compressed along the longitudinal axis of the tube.
3. The medical device of claim 1 wherein the opposing surfaces of each slit contact each other when the tube is in the stiffened state.
4. The medical device of claim 1 further comprising a sheath through which at least one of the force transmission elements extends proximally of the plurality of routing members.
5. The medical device of claim 4 wherein the sheath is substantially incompressible.
6. The medical device of claim 4 wherein a distal end of the sheath is secured to the distal segment proximally of the plurality of routing members.
7. The medical device of claim 4 wherein the sheath includes a coil tube.
8. The medical device of claim 4 wherein the sheath comprises a laser cut hypotube.
9. The medical device of claim 1 further comprising a second pair of force transmission elements coupled to the tube and actuatable to alter the tube between the flexible state and the stiffened state, wherein the force transmission elements of the second pair are coupled opposite each other to the wall of the tube and wherein equal tension forces applied to the second pair of force transmission elements compress the tube to create the stiffened state.
10. The medical device of claim 9 wherein the tension forces applied to the pairs of force transmission elements are all equal to create the stiffened state.
11. The medical device of claim 1 , wherein the tube is configured to rotate about the longitudinal axis of the tube during deformation of the regions of the tube disposed between the plurality of slits.
12. The medical device of claim 11 , wherein a distal portion of the tube is configured to rotate more than a proximal portion of the tube as the tube is altered between the flexible state and the stiffened state.
13. The medical device of claim 1 , wherein the regions of the tube disposed between the plurality of slits are arranged in a spiral formation comprising a right-hand helical path on a first length of the tube and a left-hand helical path on a second length of the tube.