Steerable arm for use in endoscopic surgery

Abstract

To provide a steerable arm with sections bending in different planes for use in endoscopic surgery.SOLUTION: The steerable arm is cut from a tube of nitinol to provide flexibility and resilience by the structure into which the tube is cut. The steerable arm includes a hollow, continuous tubular member made of an elastic material and having two bending sections. Each bending section is provided with a series of spaced gaps along the side of the tubular member. The gaps bend the corresponding section of the tubular member by closing. The series of gaps in each section is angularly offset around the axis on different sides of the tubular member, thereby allowing each section to bend in a different plane. In a preferred embodiment, four sections each bending in a different plane are provided.SELECTED DRAWING: Figure 20

Description

Technical Field

[0001] The present invention relates to the field of endoscopic surgical instruments.

Background Art

[0002] Gastrointestinal (GI) cancer is the most common cancer worldwide. According to the cancer statistics of the World Health Organization (WHO), colorectal cancer and gastric cancer are the second and third most common causes of cancer-related deaths in the world, respectively, and the number of deaths in 2018 reached 862,000 and 783,000, respectively. The prognosis of GI cancer is significantly good. The 5-year survival rate of early-stage GI cancer is over 90% worldwide.

[0003] The conventional treatment for GI cancer is surgery involving resection and anastomosis, which is associated with significant morbidity and mortality.

[0004] Preferred surgical methods for the gastrointestinal (GI) tract include guiding surgical instruments through the instrument / biopsy channel of an endoscope. A flexible endoscope is inserted through the mouth into the stomach to reach the target position or through the anus into the large intestine to reach the target position. The distal end of the endoscope is operated by a surgeon using the control handle at the proximal end of the endoscope. The endoscope has at least one biopsy channel, into which a long and flexible instrument equipped with a surgical tool at the distal tip is inserted from the proximal end of the endoscope. The most common flexible endoscope is made by Olympus, and the diameter of the biopsy channel is as large as 3.7 mm, but it can also be 2.8 mm or less.

[0005] Medrobotics has proposed a semi - automatic robotic endoscope with channels for manual surgical instruments (described in U.S. Patent No. 10016187 B1 (Patent Document 1)). The diameter of the surgical instrument is assembled from many separate joints so that it can perform articulating movements when pulled by a pair of antagonistic wires (two wires on opposite sides pull in opposite directions). To bend a joint in one direction, it is necessary to pull one wire and release or push the other wire. The individual joints are complex in design and assembly and require a wide diameter with a thickness of 4 mm. Therefore, the main drawback of this surgical instrument is that it does not fit into the biopsy channel of a general flexible endoscope.

[0006] Endomaster has proposed a similar robotic surgical instrument, which is also assembled from a separate joint - based mechanism with similar drawbacks (described in U.S. Patent Application Publication US20210186309A1 (Patent Document 2)).

[0007] Lumendi has proposed an endoscopic surgical instrument with a flexible backbone made from a single body of a flexible material such as a nickel - titanium (nitinol) tube, with separate unconnected slots cut along the sides of the tube (described in U.S. Patent Application Publication US20200305906A1 (Patent Document 3)). The straight tube can be bent in either direction by pulling wires attached to both sides of the tube. Even with this design, a complex operation of pulling one wire while releasing the wire on the opposite side is required. Furthermore, this surgical instrument is too thick to be used in the biopsy channel of a general endoscope and needs to be used in combination with its own accessory system.

[0008] Endotheia has proposed a surgical instrument that can be used with a general endoscope (described in U.S. Patent No. 10,441,371 B2 (Patent Document 4)). This design consists of nested concentric Nitinol tubes that are each pre-curved. These tubes have an overall diameter that can be extended through the biopsy channel of a general endoscope. To bend the surgical instrument towards the target location, each of the nested tubes is extended to an appropriate extent to create the necessary bend. No wire is required to bend the tubes. However, complex calculations are required to determine how much each curved tube should be extended, and control by software and robots is rather necessary. Even when manual override may be required depending on the situation, that seems unlikely. Furthermore, the lifting force of the thin tubes is too weak for some procedures. Also, the tubes cannot be bent at sharp angles, and to provide sufficient bend by extending the tubes long enough, the endoscope needs to be placed relatively far from the target site. As a result, the camera at the tip of the endoscope may be too far from the distal end of the surgical instrument, and the surgery may not be visualized properly. If the target site is too close to the tip of the endoscope, the lateral and longitudinal reach of the instrument may be limited.

[0009] Therefore, it is desirable to propose a surgical instrument that is suitable for use with a general endoscope, provides dexterous tissue manipulation, and offers the possibility of better control by the surgeon.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0011] In a first aspect, the present invention provides a steerable arm for use in endoscopic surgery, comprising: a tubular member having a proximal end and a distal end, the distal end being adapted to attach a surgical end effector, the tubular member being made of an elastic material; and a wire extending from the proximal end into the interior of the tubular member, the wire being attached to the distal end and the side surface of the tubular member, the tubular member being capable of having a bend in the longitudinal direction by the wire; wherein when the distal end of the tubular member is pulled by the wire, the bend changes, and the elasticity of the elastic material biases the tubular member such that the change in the bend is reversed when the pull on the distal end is released. A steerable arm for use in endoscopic surgery is proposed, characterized by the above.

[0012] Advantageously, the present invention provides the possibility of returning the steerable arm to its stationary shape by releasing the tensile force, thereby enabling the biasing force to be exerted. This eliminates the need for a second wire in prior art steerable techniques. This one-wire approach is easier than the prior art two-wire approach, which requires additional adjustment between pulling one wire and releasing the other wire, and saves space within the steerable arm for other components or wires.

[0013] The tubular member need not be a tube with a filled middle wall and may be any elongated member, such as a coil of loops, that provides the necessary features and functions.

[0014] Preferably, the tubular member has a first side and a second side along the axis of the tubular member, the first side being relatively more compressible than the second side, and the second side being relatively less compressible than the first side. The side of the tubular member to which the wire is attached is the first side, and when the wire is pulled, the first side is compressed and the curvature of the tubular member changes. Advantageously, the greater compressibility of the first side accommodates bending and flexing of the second side, enabling the entire manipulable arm to bend and flex. The greater compressibility of the first side and the lesser compressibility of the second side can be provided by making the first side and the second side of different materials, or by structural design.

[0015] Preferably, to further provide compressibility of the first side, the manipulable arm further comprises a gap on the first side. When the wire is pulled, the gap closes and the second side bends towards the first side, changing the bend of the tubular member. This feature relates to structurally provided compressibility and improves the inherent compressibility provided by the material of the tubular member.

[0016] Preferably, the manipulable arm further comprises a wire guide inside the tubular member to guide the translation of the wire.

[0017] Preferably, the tubular member is curved in the stationary state, with a concave surface and a convex surface existing on the tubular member, and the convex surface of the tubular member is the first side. Advantageously, this enables the manipulable arm to be bent from one-direction bending to the opposite-direction bending and to be swung across a plane by a single wire to the extent that the compressibility of the first side allows.

[0018] In the application where the tubular member is used within the biopsy channel of an endoscope, the curvature of the tubular member has the advantage that the camera at the tip of the endoscope can be positioned closer to the target tissue compared to a straight manipulable arm of the same length that is not curved. Also, due to the curvature, the body of the manipulable arm is positioned away from the center of the endoscope's field of view, so the field of view of the camera is not blocked.

[0019] Preferably, the tubular member is a tubular coil of a helical loop, and the bend of the tubular member is such that the ends of the loops on the first side are spaced apart to form a gap, and the ends of each loop on the second side abut against the ends of the adjacent loops, where the first side and the second side are on opposite sides of the tubular member. The abutting ends prevent compression and provide the lever action for bending the manipulable arm.

[0020] Due to the advantages of the helical loop structure, it is possible to cut the manipulable arm from a single original tube, which is economical and provides a continuous structure. This also provides the possibility of bending the manipulable arm by utilizing the flexibility of the loop structure while providing biasing depending on the rigidity of the material constituting the tubular member. In an embodiment, the loops on the first side are described as ribs that can open and close, and the second side is described as a backbone.

[0021] Alternatively, the loops have different helical pitches and / or variations in spacing along different portions to provide different flexibilities to different portions of the manipulable arm.

[0022] Preferably, the distal portion is more flexible than the proximal portion, and pulling a wire attached to a more distal portion of the manipulable arm advantageously prevents the more proximal portion from being unintentionally deformed. This allows the bending of the more distal portion to be controlled without affecting the bending of other more proximal portions, improving the control of the manipulable arm.

[0023] Preferably, the loop is created by making at least one helical cut in the tube.

[0024] Preferably, the manipulable arm further comprises at least one slit at the edge of at least one loop on the second side. Advantageously, the slit allows a certain degree of expansion and contraction of the backbone, increasing the flexibility.

[0025] As an option, the tubular member is a tubular coil of a helical loop, and the manipulable arm further has two rows of opposing connecting joints arranged along opposite sides of the tubular member, each connecting joint in each row rotatably connecting two adjacent loops, the opposing rows of connecting joints providing a second side, the tubular member being located at the center of the cross-section of the tubular member and having an axis along its length, the first side and the second side being arranged perpendicular to each other with respect to the axis of the tubular member.

[0026] Preferably, the tubular member is manufactured from a single material and the tubular member is of a continuous structure (i.e., remains of a monolithic structure). For example, the single material is a single tube. Advantageously, the continuous structure offers the possibility of relying entirely on the inherent strength and stiffness of the material constituting the structure without the need for additional connections or couplings to join separate parts.

[0027] As an option, it further has an elongate spring piece attached to the length of the second side by providing additional structural robustness, the elongate spring piece enhancing the biasing.

[0028] Preferably, the tubular member includes at least two sections, a respective number of wires extending from the proximal end into the inside of the tubular member, each wire being attached to the distal end of each section, the distal end of the most distal section being the distal end of the tubular member, each section being able to have a bend in the longitudinal direction of the tubular member, and when the distal ends of each section are pulled by their respective wires, the bend of each section changes, where the elasticity of the elastic material biases the tubular member such that the change in the bend of each section reverses when the pull on the distal end of each section is released.

[0029] Advantageously, each section can contribute to a different plane of movement, thereby improving the degrees of freedom of movement of the distal end of the manipulable arm.

[0030] Preferably, the change in the bend of each of at least two sections lies in different planes.

[0031] Preferably, the stiffness of each section is different such that the section located near the proximal end of the manipulable arm is larger in order to reduce the mechanical coupling effect between the sections when pulling the wires of different sections.

[0032] Generally, the manipulable arm is disposed at the distal end of the transmission tube. The transmission tube includes a channel through which a wire is passed. The proximal end of the wire is connected to a knob and / or lever for pulling the wire. When the distal end of the tubular member is pulled by the wire at the proximal end of the transmission tube, the curvature changes.

[0033] In a second aspect, the present invention proposes a method of fabricating a manipulable arm for use in endoscopic surgery from a hollow tube, the method comprising the following steps: a) providing a hollow tube having a proximal end and a distal end, the distal end being suitable for attaching a surgical end effector, the hollow tube being made of an elastic material; b) cutting the hollow tube circumferentially and along the length of the tube to make a helical cut, the helical cut creating a gap along at least one side of the hollow tube; c) inserting a wire into the proximal end of the hollow tube; and d) attaching the wire to the hollow tube, the attachment being: i) on the side of the tube with the gap; and ii) very distal from the proximal end such that the wire extends across the gap.

[0034] When the entire hollow tube is cut to form a manipulable arm, there is a possibility that the manipulable arm has a continuous structure.

[0035] By this method, a single tube of material can be preselected according to the diameter of the tube, and the dimensions of the manipulable arm can be adjusted according to the channel dimensions of the endoscope. In contrast, it is more difficult to manufacture a small manipulable arm with prior art methods that rely on assembling different parts together.

[0036] Preferably, the method further comprises the steps of holding the hollow tube at the bent position; and causing the hollow tube to remember the bend in a stationary state by plastic deformation or heat treatment.

[0037] Preferably, the method further comprises the step of cutting the hollow tube so as to leave a coupler on each loop for coupling to an adjacent loop.

Brief Description of the Drawings

[0038] It is convenient to further describe the present invention with reference to the accompanying drawings showing possible configurations of the present invention. In the drawings, like integers refer to like members. Other embodiments of the present invention are possible, and thus the particularity of the accompanying drawings should not be understood as substituting for the generality of the foregoing description of the present invention.

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Embodiments for Carrying Out the Invention

[0039] Figure 1 shows the prior art for comparison. The prior art is a manipulable arm that can be used in endoscopic surgery. This manipulable arm is composed of nested curved segments and can be extended telescopically. The end of the thinnest part can extend the farthest and is fixed with an end effector such as a pair of forceps or a diathermy knife. Each segment can contribute to the overall bend of the manipulable arm by expanding fully or partially to reach the target area. The bending of the manipulable arm is not achieved by pulling a wire.

[0040] Figure 2 shows another manipulable arm of the prior art. This manipulable arm is generally an elongated member 201 having a series of portions cut from the side of the elongated member. Two wires within the elongated member are fixed on both sides of the distal end of the elongated member. To bend the elongated member to one side, as a pair of wires for actuation and antagonism, one wire needs to be pulled and the other wire needs to be released.

[0041] Figure 3 shows an embodiment of the present invention, a flexible surgical instrument 300 for use with an endoscope 400.

[0042] The flexible surgical instrument 300 includes a transmission tube 307 that occupies most of the length of the flexible surgical instrument 300. A manipulable arm 301 is attached to the distal end 303 of the transmission tube 307. At the tip of the manipulable arm 301, a surgical end effector 403 (see the inset in Figure 4) that determines the function of the flexible surgical instrument 300, such as forceps, a diathermy knife, an injection needle, a suturing instrument, etc., is attached.

[0043] Figure 4 shows an endoscope 400 with two flexible surgical instruments 300 inserted therein. The endoscope 400 is an optical instrument that can be extended into the gastrointestinal (GI) tract through the mouth or anus and can be manipulated to reach a target position within the tract to provide a view. The endoscope 400 can include a video display connected to its proximal end and a light source and camera having a wide field of view on the distal end 411. Image transmission from the camera to the video display can be provided by an optical fiber system or a sensor chip system.

[0044] Endoscopes 400 for gastrointestinal procedures are typically over 1 m in length. The outer diameter of an endoscope 400 having two biopsy channels is typically greater than 1.2 cm. One or two channels, typically called biopsy channels 405 or instrument channels, having a diameter of 2.8 mm to 3.7 mm, can be provided in the core of the most common GI endoscopes 400. The biopsy channel 405 has a channel inlet 413 at the proximal end of the endoscope 400 and a channel outlet at the distal end 411 of the endoscope 400. The flexible surgical instrument 300 can be inserted into the biopsy channel 405 through the channel inlet. The endoscope 400 of FIG. 4 has two biopsy channels 405, one for each of the two flexible surgical instruments 300.

[0045] FIG. 5 is an enlarged view of the drawing insert of FIG. 4 and shows an exemplary arrangement of a camera 501 and a light source 503 on a cap 401 at the distal end 411 of the endoscope 400. The camera 501 provides a live view of the surgical site, the steerable arm 301, and the end effector 403 and guides the surgeon in operating the steerable arm 301.

[0046] FIG. 5a shows a steerable arm 301 having a forceps 505 as an end effector provided at its distal end. FIG. 5b shows the steerable arm 301 with a diathermy knife 507 provided as an end effector at its distal end. Other end effectors such as injection needles and suturing instruments can be attached to the distal end of the steerable arm 301 to determine the ultimate function of the arm.

[0047] FIG. 6 is a photograph that can be taken by the camera 501, showing two manipulable arms 301, each having an end effector 403 attached thereto and performing a treatment on the tissue. The two manipulable arms 301 in FIG. 6 are attached with an outer sheath that reduces friction when the flexible surgical instrument 300 is inserted into the biopsy channel 405 and provides electrical insulation.

[0048] In a preferred embodiment, the transfer tube 307 and the manipulable arm 301 have an outer diameter of 2.7 mm or less to fit into most biopsy channels 405 provided by a general GI endoscope 400. The length of the transfer tube 307 can be varied. This is determined by the design and depends on the length of the endoscope 400 in which the flexible surgical instrument 300 is used.

[0049] The manipulable arm 301 can be moved or bent by pulling a wire passed through at least one channel in the transfer tube 307. The distal ends of some of the wires are attached to different parts within the manipulable arm 301. One of the remaining wires is connected to the end effector 403.

[0050] The end of the wire 309 protruding from the proximal end 305 of the flexible surgical instrument 300 is coupled to an adapter (not shown) located outside the endoscope 400. The adapter includes a knob, a pulley, or a lever (not shown), and the ends of the wires are connected separately. By rotating or moving each knob, pulley, or lever, the respective wire is pulled. Pulling the proximal end of the wire causes the manipulable arm 301 to move or bend, or the end effector 403 to operate. The adapter can be robotically operated via electronic components and software to control the movement of the manipulable arm 301 and the end effector 403.

[0051] In surgery, the surgeon inserts the endoscope 400 into the patient's body and guides the endoscope 400 to a desired position within the digestive tract. The wire 309 extending from the proximal end of the endoscope 400 can be pulled or released by an adapter.

[0052] FIG. 7 shows a major portion of the steerable arm 301, which is a metal tube formed into a tubular coil 707 of a loop or helical metal ribbon. The steerable arm 301 has a convex surface 703 and a concave surface 701 because it bends when stationary. On the concave surface 701, the ends of the loops are closed and each end abuts the corresponding end of each adjacent loop. This prevents compression of the loops on the concave side 701. As a result, a backbone is formed on the concave side 701 of the tubular coil 707. On the convex surface 703, the ends of the loops are spaced apart, thereby forming ribs extending from the backbone. The ends of the ribs on the concave side 701 can be brought closer together or moved farther apart to expand and contract the backbone. The steerable arm 301 is flexible and can be straightened or bent to the opposite side. However, the metal is an elastic material, and the steerable arm 301 is biased to return to its original shape when the bending force is removed.

[0053] FIG. 8 is a series of schematic views of the articulating motion of the steerable arm 301. The drawing shows the end of the wire 309 for controlling the steerable arm 301 that extends through the core of the steerable arm 301 and is connected to a rib at or near the center of the steerable arm 301. The wire 309 is shown as a solid line for clarity, but a skilled reader will understand that most of the wire 309 is not visible because it is inside the steerable arm 301. The wire 309 can be fixed to the rib at or near its distal end via a knot, crimping, or other means that ensures the wire 309 remains fixed to the rib. The steerable arm can also be made of a loop helix or a tube having sections cut along the side of the tube.

[0054] The leftmost figure shows the manipulable arm 301 in a stationary state, with the backbone bent so that the concave side faces inward (Figure 8a). The ribs are on the convex side and spread out in accordance with the bend. When the wire 309 is pulled, some of the ribs approach each other, causing the backbone to bend or straighten (Figure 8b). When the wire 309 is pulled further, the ribs are pulled closer together, causing the bend of the manipulable arm 301 to reverse and bend in a direction away from the original bending direction (Figure 8c). When the pull is released, the biasing force is manifested, and the manipulable arm 301 can be returned to its stationary state shape. Due to this biasing force, the second wire for returning the manipulable arm to its original stationary state becomes redundant.

[0055] Therefore, the manipulable arm 301 can move from bending in one direction to bending in another direction within a single plane. This enables the end effector 403 on the manipulable arm 301 to manipulate tissue. This one-wire approach is easier than the prior art two-wire approach, which requires additional adjustment between pulling one wire and releasing the other wire. Also, the presence of the second wire would occupy space within the manipulable arm 301.

[0056] Figure 9 schematically shows a preferred method of manufacturing the manipulable arm 301. First, a tube 901 made of a superelastic material is prepared, which has a diameter small enough to be fed through the biopsy channel 405 of the endoscope 400 where the manipulable arm 301 is expected to be used. Generally, a diameter of 2.7 mm or less is preferred for general use. The subsequent transfer tube 307 also has a similarly small diameter and has no problem passing through the biopsy channel. A superelastic material is a material that can undergo large deformations and can immediately return to its original undeformed shape when the external stress is removed, and includes, for example, nitinol (nickel titanium) and the following alloys: Cu-Zn, Cu-Al-Ni, Au-Cd, Au-Cu-Zn, In-Tl.

[0057] As shown in FIG. 9a, the tube 901 is cut spirally along the length of the tube 901 to create the tubular coil 707. This cutting can be performed, for example, by precision machining such as laser cutting, computer numerical control (CNC) milling, or other means. FIG. 9 shows the laser source 903 used to cut the tube 901.

[0058] Other cuts are made on the side surface of the tube 901 to slice off a portion 907 of each loop. This creates a gap 905 and a rib 909 for every two adjacent loops on that side of the tube 901 (FIG. 9b). The gap 905 allows the ribs 909 to move closer to each other and accommodate the bending of the backbone 911 towards the rib side. Also, the ribs 909 can move further apart to accommodate the bending of the backbone 911 towards the backbone side (FIG. 9c). The other side of the tube 901 forming the backbone 911 is cut with minimal gaps 905 between the loops.

[0059] Note that the spiral cut is made across the entire circumference of the tube 901, including the side surface of the tube 901 that becomes the backbone 911. Thus, the ends of the loops on the backbone 911 are also cut and separated. However, the back ends of each loop are adjacent to the ends of the adjacent loops. The abutting portions prevent compression of the backbone 911 when the steerable arm 301 bends by pulling the wire 309.

[0060] As an option, in other embodiments, only one side of the tube 901 can be cut to provide the gap 905 that forms the rib 909 without making a spiral cut across the entire circumference. As a result, the side of the tube 901 that forms the backbone 911 remains integral and no cuts are made.

[0061] As an option, subsequently, the steerable arm 301 is held in the desired shape and heat treated or plastically deformed to cause the material to remember that shape.

[0062] Figures 10 and 11 are technical drawings of rib 909 and backbone 911, with backbone 911 shown in an unbent state. The left figure in Figure 10 shows the external image of the manipulable arm 301, and the right figure in Figure 10 is the corresponding cross-sectional view from the direction marked h-h. The left side of Figure 11 is a cross-sectional image in the j-j direction, and the right side of Figure 11 shows the external appearance of the corresponding manipulable arm 301.

[0063] The helical pattern can be modified to change the helical pitch (L), change in spacing (M), number of turns, cut thickness, cut shape, and slot position and size. These parameters can be adjusted to change the bending profile, range of motion, and rigidity of the backbone 911 and can be selected according to the requirements of surgical applications. Thus, the range and shape of the pre-curvature can be changed to meet different surgical requirements such as a specific approach angle of the end effector 403 of the instrument.

[0064] The stiffness, flexibility, and elasticity of the manipulable arm can be adjusted by changing the structure of the gaps and loops. For example, when the loop is thick, the flexibility of the manipulable arm becomes lower and it becomes harder. Or, when the loop is narrow, the flexibility of the manipulable arm becomes higher. The size of the gap between the loops, the width of each gap, the inclination of the gap (helical pitch), and the proximity of the gaps can all potentially affect the flexibility and restoring force. Generally, the larger the gap and the higher the loop density, the higher the deformability and flexibility of the tube. Even in an embodiment where the manipulable arm is not a loop of the coil but a simple tube having a gap sliced into the tube along the side surface of the tube, the same change in the gap can cause a similar change in the flexibility of the tube. Therefore, it is possible to manufacture a manipulable arm that is more flexible at the distal end and less flexible at the proximal end by simply cutting the distal end more finely to provide finer loops or more cut-out portions. At the ends, the finely cut loops and cut-out portions are reduced. Advantageously, this prevents the wire attached to the more distal portion of the manipulable arm from being pulled and the more proximal portion from being inadvertently deformed. Thereby, the distal end does not lose control sensitivity more than the proximal end, and the manipulable arm becomes more dexterous.

[0065] The manipulable arm 301 is manufactured from a single metal body that provides a continuous structure. By a continuous structure, it is meant not the movement between separately but connected joints, but rather something that is integrated by actually deforming the material and bends continuously. In other words, a continuous structure is usually made of a single material. Further, a continuous structure has no sharp creases or bends that can cause high stress concentration, and the sides of the continuous structure only gradually curve or become straight. In this way, the molecular structure or elemental structure of the material can give the continuous structure strength, stiffness, elasticity, and flexibility.

[0066] The continuous structure avoids the need to assemble separate parts onto the manipulable arm 301, overcoming the problems found in prior art where manipulable instruments require labor-intensive assembly of complex individual parts or interconnecting joints, and where the complexity of the parts can potentially have an impact. Further, this also reduces manufacturing time, complexity, and cost. In contrast to this embodiment, prior art manipulable arms composed of individual parts cannot be bent in a stationary state because the individual parts cannot be heated to retain memory of their position. Further, the materials used in the continuous structure can provide sufficient strength and rigidity to the manipulable arm 301 to retract / lift tissue in a surgical environment, but this cannot be achieved with an assembled structure consisting of separate parts by taking advantage of the strength of the materials.

[0067] Preferably, an eyelet 2201 (see FIG. 22) for guiding the wire 309 is provided on the inner surface of the rib. The eyelet allows axial translation of the wire 309 to facilitate the actuation of the backbone 911 and also restrains the wire 309 relative to the inside of the manipulable arm 301. The eyelet may be provided as an additional part that is manufactured separately and assembled together with the manipulable arm.

[0068] FIG. 12 shows a second embodiment where a connection joint 1201 is provided for each adjacent rib 909 to prevent the rib 909 from spreading or sliding radially, or from twisting about the long axis of the manipulable arm. FIGS. 13 and 14 correspond to FIG. 12, except that the version of FIG. 12 is shown biased to bend in a stationary state.

[0069] The connecting joint 1201 is shown in FIG. 13a as being provided on both sides of the manipulable arm 301. The edges of the rib 909 are spaced apart on either the convex side or the concave side of the curved portion. Thus, unlike the foregoing embodiment, the backbone is not defined by adjacent ribs on the concave side. Instead, the backbone is defined by the connecting joint 1201 that prevents the rib 909 from being compressed, the connecting joints 1201 are arranged in a row along the length of the manipulable arm 301, and the connecting joint 1201 provides a pivot about its periphery. The rib 909 may rotate and the backbone may bend to either side. In other words, the rib 909 and the backbone are arranged so as to be orthogonal to the axis of the tube 901.

[0070] The connecting joint 1201 minimizes bending or twisting outside the rotational plane of the joint and prevents the loop forming the rib 909 from loosening or expanding radially. Generally, the connecting joint 1201 does not provide additional rigidity to the manipulable arm 301 for it to return to its original shape when the manipulable arm 301 is bent. Elasticity and biasing are still provided by the choice of material constituting the manipulable arm 301 and by the fact that the manipulable arm 301 is of a continuous structure.

[0071] A wire 309 (not shown in this figure) extends within the manipulable arm 301 and is fixed to one edge of the most distal rib 909, which edge is on the convex side portion of the rib 909. Pulling on the wire 309 rotates each rib 909 about each connecting joint 1201 and bends the manipulable arm 301, thereby allowing the rib 909 to move in an articulating manner. Bending simply means changing the bend of the arm. Bending may mean bending the arm from a straight configuration or straightening the arm from a bent configuration. The ends of the rib 909 on the convex side of the backbone close and the ends of the rib 909 on the concave side open. Further pulling on the wire 309 reverses the bending and the manipulable arm 301 bends in the opposite direction (not shown). The manipulable arm 301 naturally returns to the stored shape when the pulling on the wire 309 is released.

[0072] This embodiment is also made by cutting a single tube of Nitinol. A portion of the tube is cut away to create spaced-apart helical loop coils, and these loops form the ribs 909 of the steerable arm 301. However, the notch leaves the shape of the male coupling joint on one side of each rib. In this case, "side" refers not to the side of the entire tube, but to the side of each rib 909 of the coil. The male coupling joint on the lower side of each rib 909 shown in the figure mates with the female coupling joint on the upper side of the adjacent rib. After being cut from the tube, the steerable arm 301 is held in the desired bend with all the coupling joints 1201 mated and heat-treated to memorize the bend.

[0073] In some variations of this embodiment, both sides of the tube around the backbone of the coupling joint can be fixed with wires respectively, and the tube can be bent to either side with a single wire. In these variations, the tube may or may not be pre-curved. Of course, using a pre-curved elastic tube, the tube can be bent to the opposite side with only a single wire and return to its original shape by the elastic biasing.

[0074] Figure 14 shows the male coupling joint 1401 and the female coupling joint 1403 separately, not mated, and each is provided on the opposite side of the adjacent rib 909. The male coupling joint 1401 has a neck with a round head and can be mated. The female coupling joint 1403 has a jaw that defines a round gap. The round jaw can rotate around the round head to enable the rib 909 to perform an articulating movement. Note that during the manufacture of the continuous structure, the male coupling joint and the female coupling joint are already joined, and Figure 14 is for illustrative purposes only.

[0075] Advantageously, the embodiment of FIG. 12 combines the advantages of a continuous device (an integrated device that does not require assembling different parts offers simplicity in manufacturing, ease of miniaturization, rigidity selectable based on the tube material and / or structure, and inherent resistance to buckling due to compliance) with the advantages of a joint-based bending segment (such as mechanical restraint to minimize axial compression and out-of-plane bending).

[0076] FIG. 15 shows a variation of a connection joint with a more simplified design. In this case, the male connection joint 1401 has simply a small round head without a neck, and the female connection joint 1403 is a shallow receptacle. Since the male connection joint has no neck, the female connection joint does not need to hook the head of the male connection joint.

[0077] The embodiments described so far can only bend and stretch within a single moving plane. To provide multiple moving planes, the embodiments can be considered modular and different parts can be cut from the same Nitinol tube as different parts of a larger manipulable arm 301. Thus, FIG. 16 shows a manipulable arm 301 made of a single tube. Similar to that of FIG. 7, this is cut such that two tubular coils 707 are connected in series. The two tubular coils 707 share the same axis but are angled such that each part can be bent in a different plane.

[0078] Thus, the backbone 911 of the upper part 1601 (the upper part shown in the figure) of the tube faces one direction, while the backbone 911 of the bottom part 1603 faces a different direction. The upper part 1601 can be actuated by one wire 309 to bend and move within a first plane, while the bottom part 1603 can be actuated by another wire 309 to bend and move within a second plane. Since the upper part 1601 extends from the lower part 1603, moving the lower part 1603 also moves the upper part 1601. This provides the surgeon with greater freedom when orienting the end effector 403 on the manipulable arm 301.

[0079] Note that in the embodiments, the meaning of "coaxial" does not require the axis to be straight. The axis is curved along the bending shape of the steering arm 301 and is continuous.

[0080] FIG. 17 shows a method of manufacturing a steerable arm 301 having a plurality of sections. FIG. 17a shows how a helical cut is made along and around the entire tube 901 to produce a looped tubular coil 707. Subsequently, as shown in FIG. 17b, further cuts are made in the side of the tubular coil 707 to remove a portion of each upper loop. This forms a gap 905 between the loops and a rib 909. Such further cuts are also made at the bottom of the tube, but on different sides of the tubular coil 707. As a result, a backbone 911 at the bottom is formed. Thus, the upper portion can be bent in one direction as shown in FIG. 17c, while the lower portion can be bent in a different direction as shown in FIG. 17d. FIG. 18 is a technical drawing of a tube cut to provide a backbone 911 in the upper portion 1601 on a side different from the backbone 911 of the bottom 1603. Finally, the upper portion 1601 is held in a bent state to the desired shape, the bottom 1603 is held in a bent state to a different desired shape, and a heat treatment (not shown) is performed to memorize the overall shape.

[0081] Although it is optional to cut the tube so that the upper backbone and the lower backbone bend in exactly opposite directions, this means that both the upper and lower portions can bend even if they are in the same plane and in opposite directions. Alternatively, instead, the upper backbone and the lower backbone are angularly offset along the axis.

[0082] Figure 19 schematically shows how the embodiment of FIG. 16 operates. In the figure, the upper portion 1601 of the manipulable arm 301 is made to bend in the left direction of the figure when stopped. The lower portion 1603 is made to bend to the right when at rest. As a result, the manipulable arm 301 has a shape like an inverted S. The bend of the upper portion 1601 of the manipulable arm 301 extends inside the manipulable arm 301 and can be reduced by pulling a single wire 309 that is fixed. By further pulling, the curvature can be reversed towards the rib side.

[0083] Similarly, pulling the wire 309 can straighten the lower portion 1603. By further pulling the wire 309, the curvature can even reverse towards the rib side. In this case, the wire 309 extends inside the manipulable arm 301 and is fixed to one of the ribs near the distal portion of the lower part, or alternatively to the proximal most portion of the upper part. This is because the distal portion of the lower part 1603 ends where the proximal portion of the upper part 1601 begins. Thus, the most distal rib of the lower portion 1603 is the rib just below the backbone 911 of the upper portion 1601.

[0084] When both wires 309 are pulled completely, the inverted S shape of the manipulable arm 301 is reversed and all the ribs of both the upper portion 1601 and the lower portion 1603 of the manipulable arm 301 are closed.

[0085] Figure 20 shows another embodiment including different parts composed from the previous embodiment. To manufacture the embodiment of FIG. 20, different parts of the same metal tube are cut in different ways and each part can be bent in a different plane. A corresponding number of wires are provided within the channels of the manipulable arm 301 and each wire 309 is attached to the distal end of its respective section to control the bend of that section.

[0086] FIG. 20a on the left side of the drawing shows the manipulable arm 301 in a stationary state. FIG. 20b on the right side shows the various directions in which each part is moved or bent by the action of the respective wire 309.

[0087] The manipulable arm 301 of FIG. 20 has four parts 2001, 2003, 2005, 2007. The first distal part 2001 of the manipulable arm 301 is made in the same way as in the embodiment of FIG. 12. Immediately below this first part are a second part 2003 and a third part 2005, which together correspond to the embodiment of FIG. 16.

[0088] The first part 2001 and the second part 2003 are axially offset such that the first part 2001 can bend in a first plane 2009 while the second part 2003 can bend in a second plane 2011 that makes an angle with the first plane. The second part 2003 and the third part 2005 are also axially offset such that the third part 2005 can bend in a third plane 2013 that makes an angle with the second plane 2011. Thus, the three parts 2001, 2003, 2005 can move in different planes 2009, 2011, 2013, providing three degrees of freedom of movement.

[0089] The fourth part 2007, which is below the third part 2005 as shown, is a coupler that can be attached to a corresponding coupler on the transmission tube 307 by various methods including welding, adhesion, or mechanical means. When the transmission tube is twisted at the proximal end of the endoscope, the manipulable arm 301 can be rotated by the coupling, adding further movement.

[0090] FIG. 21 shows a variant of the embodiment of FIG. 20. The main section of the manipulable arm has the embodiment shown in FIG. 16, and at both ends thereof are provided the embodiments of FIG. 12. At the proximal end is provided a coupler that connects the embodiment to the transmission tube. Thus, this manipulable arm 301 has four different sections extending from the coupler, each of which can bend in a different plane.

[0091] In yet another embodiment shown in FIG. 21a, this embodiment comprises a coupler at the bottom, followed by a second section fabricated according to the embodiment of FIG. 12 thereon, and followed by the next two-section embodiment of FIG. 16 thereon. The end effector is used by the distal end of the embodiment of FIG. 16. In this embodiment, since the gap between the two parts is larger, the two-section part is more flexible than the second section. Similarly, the embodiment of FIG. 15 has a more flexible distal section connected to a less flexible proximal section.

[0092] FIG. 22 shows a further embodiment in which a slit 2203 is provided in the backbone 911 in the embodiment of FIG. 7. The slit 2203 is not made all around the manipulable arm 301, but is only cut into the backbone 911 from the side of the manipulable arm. Preferably, the slit 2203 is provided by removing a thin portion from the backbone 911. The slit 2203 structurally reduces the resistance of nitinol and enables the backbone 911 to straighten more easily when the wire 309 pulls on the rib side, resulting in improved dynamic performance. Note that in this case as well, the backbone 911 is quite resistant to compression despite the slit 2203. As an option, more cuts can be made in the distal portion of the embodiment to make the distal portion more flexible than the proximal portion.

[0093] Figure 23 shows the process of using laser 903 to cut tube 901 in a spiral to provide ribs. The spiral cut shown in Figure 23a is not performed all at once along the entire length of tube 901. If the spiral were cut along the entire length of tube 901 all at once, the resulting looped tubular coil would be too thin and a slit could not be made in the backbone. Instead, only a short section of the tube is cut in a spiral each time, and immediately afterwards, the side of the tube that will become the backbone is sliced shallowly. Then, the next spiral cut is made continuously starting from where the first spiral cut ended. Figure 23c shows the state where after the tube is cut satisfactorily, the resulting manipulable arm 301 is bent into the desired shape and heat-treated to memorize that shape, with the backbone on the concave side and the ribs on the convex side.

[0094] Figure 24 shows how the embodiment of Figure 22 operates. Figure 24(a) shows the rest state of the manipulable arm 301 of Figure 22. Figure 24(b) shows the manipulable arm 301 extended straight with the slit open. Figure 24(c) shows the state where the slit in the backbone is further open and the bending is reversed and bent to the opposite side.

[0095] Figure 25 shows a modification of the embodiment of Figure 7, where the rigidity of the backbone 911 is enhanced by attaching a reinforcing element 2501, such as a hard but curved metal piece, to the inner surface of the backbone. The reinforcing element helps to quickly restore the shape of the backbone 911 when the tension of the most distal rib 909 is released, thereby improving the transmission response time and reducing mechanical hysteresis. The reinforcing element 2501 can be considered as a spring. The reinforcing element has sufficient flexibility so that it can straighten the backbone 911 when the wire 309 is actuated. In this embodiment, the wire is not drawn to follow the curve of the manipulable arm to show that in all cases, it is not necessary to provide a wire guide to guide the movement of the wire.

[0096] Such reinforcing elements can be provided in different sections of the backbone 911 in the embodiment of Figure 20 respectively.

[0097] Figure 26 shows yet another embodiment, where the strip 2501 of the reinforcement element is not made of a very flexible material, but springs 2601 are provided at both ends of the reinforcement element. The springs 2601 are fixed at appropriate positions inside the reinforcement element. The springs 2601 can extend when the operable arm 301 bends. However, the springs 2601 enhance the biasing of the operable arm 301 and quickly restore the stored shape when the tension on the most distal rib 909 is released. This improves the transmission response time and reduces mechanical hysteresis. That is, the effect of the tension on the wire 309 can be more easily seen in the operable arm 301.

[0098] To further improve the responsiveness of the operable arm 301, it is preferable to pre-tension all the wires 309 connected to the operable arm 301. That is, all the wires 309 are pulled taut in preparation for use, so that as a result, the section of the operable arm 301 can move as soon as the wires 309 are further pulled. If the wires 309 are not pre-tensioned and are slack, backlash may occur, and as a result, a delay will occur before the operable arm 301 responds to the tension on the wires.

[0099] Figure 27 shows a more general embodiment, where the steerable arm 301 comprises a hollow elongated member 2701 that is more elastic on one side of the axis marked x and more rigid on the other side of the axis marked y. The elongated member is shaped, molded, or heat treated so that it permanently bends towards the more rigid side at rest. The material of the hollow elongated member can remain bent when at rest, but has sufficient elasticity to be straightened or conversely bent by applying an appropriate force. Similar to the previous embodiments, the bending and biasing of the flexure portion provides the possibility of swinging the steerable arm 301 on a plane using a single wire 309. The hollow elongated member can be made from two different polymers that are co-extruded such that each polymer forms the side surface of the hollow elongated member. In this case, a more rigid material can be provided on the convex side so that the distal end of the steerable arm 301 does not shorten when pulled by the wire 309. A more extensible material can be provided on the concave side to accommodate the bending of the steerable arm 301.

[0100] So far, the foregoing embodiments have been described and illustrated as having the wire 309 fixed to the side surface of the curved tube, i.e., the side surface farthest from the backbone. This provides a more effective lever action when pulling on the rib to bend the backbone. However, fixing the wire to the backbone side of the curved tube is within the scope of the intent of this description.

[0101] Accordingly, an embodiment includes a steerable arm 301 for use with an endoscope 400 to operate a surgical tool. The distal end is suitable for attaching a surgical end effector. The tubular member is made of an elastic material, and the wire 309 extends from the proximal end into the interior of the tubular member. The wire is attached to the distal end and the side surface of the tubular member. The tubular member can have a bend in the longitudinal direction. When the distal end of the tubular member is pulled by the wire, the bend changes. The elasticity of the material biases the tubular member so that the change in the bend is reversed when the pull on the distal end is released.

[0102] In the above description, the preferred embodiments of the present invention have been described. However, it will be understood by those skilled in the art that many changes or modifications can be made in the details of the design, structure, or operation without departing from the scope of the present invention as set forth in the claims.

[0103] For example, while the loop is described as being cut out of a tube, in some embodiments, the rib could be a simple extension of the curved backbone, with one end attached to the backbone and the other end free, like a cantilever beam.

[0104] For example, the flexible surgical instrument 300 can be adapted to be used with other types of devices similar to the endoscope 400, such as a transnasal endoscope 400 or a transurethral resectoscope. If these devices do not have an internal channel for inserting the flexible surgical instrument 300, an additional sheath can be fabricated that can be slid over the device to form a channel for the flexible surgical instrument 300.

Claims

**Claim 1** An operable arm for attachment to an instrument channel of an endoscope for endoscopic surgery, comprising: A hollow continuous tubular member of elastic material having two bending sections, each said bending section having a series of spaced gaps along the side surface of said tubular member, said gaps causing said section of said tubular member to bend by closing, and having a hollow continuous tubular member; Said series of gaps in each said section are angularly offset about an axis on different sides of said tubular member, whereby each said section bends in a different plane; An operable arm for attachment to an instrument channel of an endoscope for endoscopic surgery, characterized in that. **Claim 2** An operable arm for attachment to an instrument channel of an endoscope for endoscopic surgery according to claim 1, characterized in that at least one of said sections is curved in a stationary state. **Claim 3** An operable arm for attachment to an instrument channel of an endoscope for endoscopic surgery according to claim 1, characterized in that each said section can be bent by a wire at the distal end of said section, and said section can return to its original shape by the repulsive force of the material. **Claim 4** At least one of said sections of said tubular member is a coil of a helical loop spaced to provide a gap; A connecting joint is provided between two said loops, and said loops bend and bend said section when closed; An operable arm for attachment to an instrument channel of an endoscope for endoscopic surgery according to claim 1, characterized in that.

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