SYSTEMS AND METHODS FOR CABLE-BASED TISSUE REMOVAL
Systems and methods for treating disc herniation include surgical and endoscopic access and removal of disc tissue. The tissue removal devices that may be used include flexible elongate members, such as a cable, that may be inserted into a vertebral disc and rotated to pulverize the disc material and facilitate its removal.
1 . A system for tissue removal, comprising:
a motor configured to rotate at a speed of at least 1000 rpm;
a rotatable shaft assembly coupled to the motor, wherein the rotatable shaft assembly comprises a distal coupling site and a proximal coupling site comprising a proximal surface opening; and
a flexible elongate member, comprising a distal section coupled to the distal coupling site of the rotatable shaft assembly and a proximal section slidably positioned in the proximal surface opening, and a middle section therebetween;
wherein the flexible elongate member has a retracted configuration and an extended configuration wherein a perpendicular distance between the middle section of the flexible elongate member and the rotatable shaft assembly is greater in the extended configuration than in the retracted configuration.
2 . The system of claim 1 , wherein the flexible elongate member comprises a flexible multi-filament elongate member.
3 . The system of claim 2 , where the flexible multi-filament elongate member comprises no more than about ten filaments.
4 . The system of claim 1 , wherein the proximal surface opening and the distal surface opening are longitudinally aligned.
5 . The system of claim 1 , wherein the proximal surface opening and the distal surface opening are longitudinally offset.
6 . The system of claim 1 , wherein the rotatable shaft assembly further comprises a groove between the proximal surface opening and the distal surface opening.
7 . The system of claim 6 , wherein the groove is a helical groove.
8 . The system of claim 7 , wherein the helical groove has variable pitch.
9 . The system of claim 1 , wherein the rotatable shaft assembly further comprises a narrow segment located between the proximal surface opening and the distal surface opening.
10 . The system of claim 1 , wherein the perpendicular distance between the middle section of the flexible elongate member and the rotatable shaft assembly in the extended configuration is equal to or greater than about the average diameter of the rotatable shaft assembly.
11 . The system of claim 10 , wherein the perpendicular distance between the middle section between the middle section of the flexible elongate member and the rotatable shaft assembly in the extended configuration is equal to greater than about twice the average diameter of the rotatable shaft assembly.
12 . The system of claim 1 , wherein the rotatable shaft assembly comprises a distal penetrating tip.
13 . The system of claim 1 , wherein the length of the flexible elongate member outside of the rotatable shaft assembly is different in the retracted configuration and the extended configuration.
14 . The system of claim 1 , wherein the distance between the distal coupling site and the proximal surface opening is unchanged in the retracted configuration and the extended configuration.
15 . The system of claim 1 , wherein the flexible elongate member comprises at least one rigid section and at least one flexible section.
16 . The system of claim 15 , wherein the flexible elongate member comprises at least two rigid sections.
17 . The system of claim 15 , wherein at least one rigid section is a linear rigid section.
18 . The system of claim 16 , wherein the flexible elongate member comprises a proximal rigid rod and a distal rigid rod interconnected by a flexible cable.
19 . The system of claim 18 , wherein the proximal rigid rod is located in the proximal surface opening.
20 . The system of claim 19 , wherein the proximal rigid rod is located in the proximal surface opening when the flexible elongate member is in the extended configuration.
21 . The system of claim 1 , wherein at least a portion of the flexible elongate member comprises a grit surface with an average grit number in the range of about 200 to about 500.
22 . The system of claim 1 , wherein the flexible elongate member has a flexural modulus that is less than a flexural modulus of intact bony tissue.
23 . The system of claim 22 , wherein the flexible elongate member has a flexural modulus that is less than a flexural modulus of intact annular fibrosis tissue.
24 . The system of claim 1 , wherein the flexible elongate member has a generally uniform flexural modulus along its length.
25 . The system of claim 1 , wherein the rotatable shaft assembly is coupled to the motor by a bendable driveshaft.
26 . The system of claim 25 , further comprising a steering assembly configured to bend the driveshaft.
27 . The system of claim 1 , wherein a ratio of the perpendicular distance between the middle section of the flexible elongate member and the rotatable shaft assembly in the extended configuration to a diameter of the rotatable shaft assembly is at least about 3:1.
28 . The system of claim 1 , wherein a ratio of the perpendicular distance between the middle section of the flexible elongate member and the rotatable shaft assembly in the extended configuration to a diameter of the rotatable shaft assembly is at least about 5:1.
29 . The system of claim 1 , wherein the flexible elongate member comprises a polymeric coating.
30 . The system of claim 29 , wherein the polymeric coating comprises polyimide.