JOINT COMPONENT

Abstract

A surgical instrument having a proximal end, a distal end and a shaft, the shaft comprising a plurality of joint components connected in series, each joint component comprising first and second connectors, which connectors are axially spaced apart from one another at first and second ends of a respective joint component, characterised in that the first connector comprises a first rolling surface, and the second connector comprise a second rolling surface, and wherein each joint component comprises a first spur gear extending from the first rolling surface, and a second spur gear extending from the second rolling surface, wherein the first rolling surface of a first joint component is engageable with the second rolling surface of a second joint component to form a rolling joint, and the second rolling surface of the first joint component is engageable with a first rolling surface of a third rolling joint.

Claims

1. A surgical instrument, comprising: a proximal end; a distal end; and a shaft, the shaft comprising a plurality of joint components connected in series, each joint component comprising first and second connectors, which connectors are axially spaced apart from one another at first and second ends of a respective joint component, characterized in that the first connector comprises a first rolling surface, and the second connector comprise a second rolling surface, and wherein each joint component comprises a first spur gear extending from the first rolling surface, and a second spur gear extending from the second rolling surface, wherein the first rolling surface of a first joint component is engageable with the second rolling surface of a second joint component to form a rolling joint and the second rolling surface of the first joint component is engageable with a first rolling surface of a third rolling joint.

2. The surgical instrument of claim 1, wherein each joint component comprises two first connectors and two second connectors, the first connectors being positioned at the first end of the joint component and the second connectors being positioned at the second end of the joint component, and wherein each joint component comprises two first spur gears and two second spur gears, each spur gear extending from a respective rolling surface.

3. The surgical instrument of claim 2, wherein the two first connectors are positioned opposite to one another at the first end of a respective joint component, and the two second connectors are positioned opposite one another at the second end of the respective joint component, the second connectors being approximately 90 degrees out of phase with the first connectors.

4. The surgical instrument of claim 3, wherein each joint component has a substantially circular cross section, with the two first connectors being diametrically opposed to one another along a first diameter, and the two second connectors being diametrically opposed to one another along a second diameter, the first and second diameters being substantially orthogonal to one another.

5. The surgical instrument of claim 1, wherein each joint component comprises a wall defining a hollow interior.

6. The surgical instrument of claim 5, wherein each joint component further comprises an inner channel extending axially through the joint component.

7. The surgical instrument of claim 6, wherein the inner channel of each joint component comprises a central channel portion and a peripheral channel extending from the central channel portion to an inner surface of the outer wall.

8. The surgical instrument of claim 5, wherein each joint component further comprises a wall channel extending axially along an inner surface of the wall.

9. The surgical instrument of claim 8, wherein the peripheral channel of each joint component extends from the central channel to the wall channel of the respective joint component.

10. The surgical instrument of claim 1, comprising a plurality of joint units, each joint unit comprising three joint components forming two rolling joints.

11. The surgical instrument of claim 1, further comprising a drive mechanism for driving the joint components.

12. The surgical instrument of claim 11, wherein the drive mechanism comprises a plurality of tendons.

13. The surgical instrument of claims 11, further comprising an actuator for operatively connected to the drive mechanism.

14. The surgical instrument of claim 13, further comprising a switch for switchably connecting the actuator to the drive mechanism.

15. The surgical instrument of claim 14, wherein the switch is a three-way switch.

16. The surgical instrument of claim 14, wherein the switch comprises a differential mechanism coupled with an electro-magnetic break.

17. The surgical instrument of claim 14, wherein the surgical instrument is switchable between a floppy state, an actuation state and a stiff state.

18. A joint component for a surgical instrument, comprising: first and second connectors axially spaced apart from one another at first and second ends of a respective joint component, characterized in that the first connector comprises a first rolling surface, and the second connector comprise a second rolling surface, and wherein each joint component comprises a first spur gear extending from the first rolling surface, and a second spur gear extending from the second rolling surface, wherein the first rolling surface of a first joint component is engageable with the second rolling surface of a second joint component to form a rolling joint and the second rolling surface of the first joint component is engageable with a first rolling surface of a third rolling joint.

19. A joint unit forming part of a surgical instrument, comprising: three joint components forming two rolling joints, each joint component, comprising: first and second connectors axially spaced apart from one another at first and second ends of a respective joint component, characterized in that the first connector comprises a first rolling surface, and the second connector comprise a second rolling surface, and wherein each joint component comprises a first spur gear extending from the first rolling surface, and a second spur gear extending from the second rolling surface, wherein the first rolling surface of a first joint component is engageable with the second rolling surface of a second joint component to form a rolling joint and the second rolling surface of the first joint component is engageable with a first rolling surface of a third rolling joint.

20. A method for operating a surgical instrument, comprising the steps of: inserting the surgical instrument into a patient via a natural orifice or incision, the surgical instrument including: a proximal end; a distal end; and a shaft, the shaft comprising a plurality of joint components connected in series, each joint component comprising first and second connectors, which connectors are axially spaced apart from one another at first and second ends of a respective joint component, characterized in that the first connector comprises a first rolling surface, and the second connector comprise a second rolling surface, and wherein each joint component comprises a first spur gear extending from the first rolling surface, and a second spur gear extending from the second rolling surface, wherein the first rolling surface of a first joint component is engageable with the second rolling surface of a second joint component to form a rolling joint and the second rolling surface of the first joint component is engageable with a first rolling surface of a third rolling joint; switching the instrument to an actuation state; carrying out a required medical procedure; and then removing the instrument from the patient.

21. The method of claim 20, further comprising an initial step, carried out before the step inserting the surgical instrument, for switching the instrument to the floppy state.

22. The method of claim 20, further comprising an initial step, carried out before the step of inserting the surgical instrument, for switching the instrument to the stiff state.

23. The method of claim 20, further comprising a step carried out after the step of carrying out a required medical procedure of switching the instrument to a floppy state to thereby remove the instrument from the patient.

24. The method of claim 20, further comprising a step carried out after the step of carrying out a required medical procedure of switching the instrument to a stiff state to thereby remove the instrument from the patient.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

[0080] FIG. 1a is schematic representation of a surgical instrument made in accordance with embodiments of the first aspect of an embodiment of the invention;

[0081] FIG. 1b is a schematic representation of the surgical instrument of FIG. 1a showing the degrees of freedom of the instrument;

[0082] FIGS. 2a to 2c are schematic representations of a joint unit forming part of the surgical instrument in FIG. 1;

[0083] FIGS. 3a to 3c are schematic representations of the joint units shown in FIGS. 2a to 2c showing movement between the joint units;

[0084] FIG. 4 is a schematic representation of a plurality of the joint units forming the surgical instrument of FIG. 1 showing tendons passing through the instrument;

[0085] FIG. 5 is a schematic representation of the joint units of FIG. 4 with some of the joint units removed to show the route taken by the tendons and Bowden cables;

[0086] FIG. 6 is a top view representation of one of the joint components forming the surgical instrument of FIG. 1a showing the hollow interior of the joint component;

[0087] FIGS. 7a and 7b are a cross sectional representations of one of the joint components forming the surgical instrument of FIG. 4 showing the angled channels;

[0088] FIGS. 8 to 11 are schematic representations of a switch in the form a differential mechanism for controlling the connection between a motor, and a brake and the tendons in the surgical instrument illustrated in FIG. 1a;

[0089] FIG. 12 is a schematic representation of a back drivable actuation pack forming part of the surgical instrument shown in FIG. 1a;

[0090] FIG. 13 is a schematic representation of an alternative back driveable actuation pack that could be used to drive the surgical instrument as shown in FIG. 1a; and

[0091] FIG. 14 is a schematic representation showing how the dimensions of the surgical instrument illustrated in FIG. 1a may be calculated in order to fit a particular patient and in this case the oesophagus of a particular patient.

DETAILED DESCRIPTION

[0092] Referring to the figures, a surgical instrument according to a first aspect of the embodiments of present invention is designated generally by the reference numeral 2. The surgical instrument 2 is in the form of a snake-like robot which may be used for many medical procedures such as intra-luminal procedures and procedures which use the natural orifices of a patient in order to carry out the procedure.

[0093] The surgical instrument 2 comprises a plurality of joint components 4 which are linked together in series as will be described in more detail below. The joint components may be regarded as vertebrae.

[0094] The surgical instrument comprises a proximal end 8 and a distal end 10, and the joints 6 extend along an axis of the surgical instrument 2 between the proximal end and the distal end.

[0095] The surgical instrument 2 further comprises an actuator 100 which is operatively connected to the surgical instrument 2 at the proximal end thereof.

[0096] Each joint 4 comprises two first connectors 12 positioned at a first end 14 of the joint, and two second connectors 16 spaced apart from the first connectors 12 at a second end 18 of the joint 4. Each of the first connectors 12 comprises a first rolling surface 20, and each of the second connectors 14 comprises a second rolling surface 22.

[0097] First spur gears 24 extend from each of the first rolling surfaces 20, and second spur gears 26 extend from the second rolling surfaces 22.

[0098] When adjacent joint components 4 engage with one another, the first spur gears 24 on one joint component 4 will engage with the second spur gears 26 on a second joint component 4. When adjacent joint components 4 engage with one another in this manner, a rolling joint 6 is formed. The spur gears 24, 26 reduce the likelihood that one joint component 4 will slip relative to the adjacent joint component 4 during movement of the joint formed by the two joint components.

[0099] The second connectors 16 of each joint component 4 are also spaced apart from one another at the second end 18 of the joint component 4. However, the second connectors 16 are offset from the first connectors 12 by, in this example, about 90. This means that a different range of movement may be possible between for example a first and third joint component and a first and second joint components.

[0100] In this embodiment of the invention, the joint components 4 are arranged to form joint units 30 as shown in FIGS. 2a to 2c and 3a to 3c, for example. Each joint unit comprises first, second and third joint components 32, 34, 36 respectively. Due to the orientation of the first and second connectors 12, 18 on each joint component, a different range of movement may be possible at the rolling joint 6 formed between the second and third joint components 34, 36, than at the rolling joint 6 formed between the first 32 and second 34 joint components. The movement of the rolling joint 6 will be described in more detail below.

[0101] In this embodiment of the invention, each joint component 4 is substantially circular in cross-section as shown in FIG. 6. In this embodiment therefore the first connectors 12 are positioned diametrically opposed from one another along a first diameter 38 and the second connectors 16 are also positioned diametrically opposed to one another along a second diameter 40 to one another, but offset such that the first diameter 38 is substantially orthogonal to the second diameter 40.

[0102] The surgical instrument 2 has thirteen possible degrees of freedom, comprising 12 rolling joints 6, and a revolute joint 101 at the proximal end 8 of the instrument 2. It is to be understood, however, that in other embodiments of the invention the surgical instrument may have a different number of degrees of freedom.

[0103] These degrees of freedom are illustrated in FIG. 1b by rods 102. It is to be understood that the rods 102 do not exist in embodiments of the invention but are included in FIG. 1b to illustrate the degrees of freedom in the instrument.

[0104] Because of the way the that the joint components 4 are arranged to form joint units 30, parallel adjacent rods 102 are coupled together reducing the effective number of degrees of freedom to 7.

[0105] As also shown in FIGS. 6, 7a and 7b, each joint component 4 comprises a wall 42 which defines a hollow interior 44 of the joint component 4. In the illustrated embodiments, each joint component 4 further comprises an inner channel 46 extending axially through the joint component 4. The inner channel 46, in this embodiment comprises a central portion 48 and four peripheral channels 50 each of which peripheral channels 50 extends to the wall 42. Each joint component 4 further comprises wall channels 52 (in this case 4). In this embodiment of the invention there is a wall channel 52 positioned at the end of each peripheral channel 50.

[0106] In this embodiment of the invention the peripheral channels 50 extend in a direction that forms an angle of less than 90 with the axis of the joint component 4. In other words, the peripheral channels 50 are angled relative to the inner channel 46 as shown in FIGS. 7a and 7b.

[0107] In the embodiment of the invention, the joints 6 are driven by tendons 54, arranged in pairs in order to control movement of the rolling joints 6. In this embodiment of the invention two pairs of tendons will be attached to a particular joint component 4 in order to control between them two rolling joints, as will be described in more detail below.

[0108] With respect to the joint unit 30 shown in FIGS. 2a, 2b and 2c, and 3a, 3b and 3c two pairs of tendons 56, 58 are used to control movement of rolling joints 610 and 620 respectively. The rolling joint 610 is formed between joint components 34 and 36 and rolling joint 320 is formed between rolling joints 32 and 34.

[0109] Both of the pairs of tendons 56, 58 are attached to the third joint component 36 at tendon attachment portions 60. The tendon pairs 56, 58 will extend from the tendon attachment portions 60 within Bowden cables 70 which extend through the surgical instrument down to the proximal end 8 of the surgical instrument where the tendons 56, 58 will be operatively connected to actuator 100. The two pairs 56, 58 of tendons are used to control movement of both of the rolling joints 610, 620 illustrated in FIGS. 2a to 2c as shown particularly in FIGS. 3a and 3b. Combined motion of the two tendon pairs 56, 58 will induce the motion in either the top rolling joint 610 or the bottom rolling joint 620. If a single pair of tendons is moved, a combined motion of both the rolling joints 610, 620 will be induced. Movement of both pairs of tendons together in the same direction will induce the motion in one of the rolling joints only. Similarly, if both of the tendons are moved in the opposite direction the other rolling joint will be moved. By combining the motion of the two tendon pairs it is possible to precisely control the position of each rolling joint 610, 620.

[0110] In the joint units illustrated in FIGS. 2a to 2c, and 3a to 3c, another two pairs of tendons 54 will be attached to the joint component 32 in order to control movement of the two rolling joints in the adjacent joint unit.

[0111] In the surgical instrument illustrated in FIG. 1 it will be desired to have twelve pairs of tendons (twenty-four tendons) in total, with two pairs of tendons being attached to every other joint component 4 as described hereinabove with reference to the joint unit 30 shown in FIGS. 2a to 2c.

[0112] Each tendon will run through a Bowden cable 70 as shown in FIGS. 5, and 7b for example. This is to allow force transmission to specific points in the body of the surgical instrument 2 and to reduce friction. The Bowden cable 70 will be kept as close as possible to the axis of the surgical instrument 2 in order to limit the stress induced by the rotation of the rolling joint 6. In this embodiment the Bowden cables 70 carrying the tendons 54 will extend through the central portion 48 of the inner channel 46 of each joint component 4, until the tendons reach the joint component 4 to which they are to be attached.

[0113] In order to compensate for the variation in path length on each side of a rolling joint 6, the Bowden cables 70 may freely translate individually. This is possible since the base of the Bowden cables is left loose. This feature together with the central location of the Bowden cables 70 may result in a reduction of cross-talk between tendons 54 and will also reduce the risk of herniation.

[0114] Once it is necessary to route the tendons 54 to the particular joint component 4 to which they are to be attached, it is advantageous to ensure that the tendons extend as closely as possible to the wall 42 of each joint component to ensure a large force transmission is achieved. The tendons 54 therefore should be routed from a central portion 48 of the inner channel 46 to an outer side of the respective joint components. This is achieved due to the peripheral channels 50 inside the joint component 4 which guide the Bowden cables 70 from the central portion 48 to the wall channel 52 positioned on the wall 42 of the joint component 4.

[0115] The peripheral channels are also able to retain a tip of the Bowden cable 70 due to a stopper having a smaller hole through which the tendon may pass through. During robotic endoscopy surgery, it may be important to be able to quickly retract the robot in case of unforeseen emergencies. The surgical instrument 2 which is in the form of a snake-like robot is appropriate for use in such surgery. This instrument 2 is equipped in this embodiment with actuator 100 which allows the instrument 2 to switch between three different states. These three states are possible through use of a back drivable actuation pack 110 illustrated in FIG. 12, or back drivable actuation pack 210 illustrated in FIG. 13.

[0116] The actuation pack 110 comprises a three-way switch 112 which is shown schematically in FIGS. 8 to 11. In this embodiment of the invention, the three-way switch 112 is a differential mechanism of the type often used in automobiles. The differential mechanism 114 is coupled with an electro-magnetic brake 116 and motor 118 to form the three-way switch. One differential is used for each degree of freedom (DOF) of the instrument 2. In this case therefore seven differentials are required for the seven degrees of freedom show in FIG. 1b. Each actuation pack 110 drives two tendons pairs in an antagonistic actuation. This will generally be achieved using opposite capstans as a tendon is pulled by a first capstan, the corresponding paired tendon is loosened by an opposite capstan. Two tendon pairs are controlled by each actuation pack 110 using four capstans, thus reducing the total number of actuation motors 118 required to control the robot from 13 to 7. The principle of operation of the three modes is described below.

Floppy State

[0117] In this mode the body of the surgical instrument 2 is manually back drivable. In this mode all of the tendons 54 of the instrument 2 are disengaged from the motors 118 by releasing the brake 116. This allows the respective joint 6 to rotate freely. This mode is useful for manual insertion or retraction as performed during standard endoscopic procedures. This mode is depicted in FIG. 10.

Actuation State

[0118] In this mode the body of the instrument 2 is actuated by locking the brake 116 and using the motor 118. This mode can be used for follow-the-leader navigation and inspection of a patient's anatomy. This mode may also be used for motion stabilisation such as breathing motion compensation and target locking whilst working on moving organs. This mode is depicted in FIG. 11.

Stiff State

[0119] In this mode the body of the instrument 2 is rigid. This offers a stable platform on which to perform tissue manipulation using two surgical instruments 2 passing through available channels within a patient. This state may be accomplished by locking both the brake 116 and the motor 118. This mode is depicted in FIG. 9.

[0120] The instrument 2 may be tailor-made to fit individual patients and almost any human anatomy within any particular patient.

Design

[0121] In order to provide tailor-made instruments, it is desirable to design the diameter of each joint component 4 and the length of each joint component to provide a suitably dimensioned surgical instrument 2.

[0122] The desired parameters are determined from a knowledge of the diameter and bending radius of the passage through which the instrument is to be passed. For example, if the instrument is to be passed through the oesophagus 200 of a patient (FIG. 14), then knowing the dimension of the oesophagus will enable an appropriately dimensioned instrument 2 to be made.

[0123] The relevant information may be obtained from pre-operative imaging. The diameter and length of the joint component 4 may then be calculated to ensure safe navigation without collision during operation of the instrument 2. To optimise the rolling joint range of motion an optimisation algorithm is used to optimise the various rolling joint parameters. The optimisation algorithm considers the tendon placement as well as various collisions (tendon-joint collision, joint-joint collision) in the optimisation process. The resulting optimised joint may be made patient specific. An example of such optimisation is set out below.

[0124] If the patient's oesophagus is 15 mm in diameter, for example, then the diameter of the joint component 4 should be smaller than 11 mm in order to allow for a 4 mm safety margin.

[0125] For the joint length, the bending radius of the oesophagus should be known to ensure that two consecutive joints in a straight and aligned configuration will not collide with the anatomy of the patient. This may be achieved in a simulation as shown in FIG. 14 where the maximum length available is calculated at 36.77/2=18.38 mm of joint length.

[0126] In the illustrated embodiment, the necessary parameters were determined using a review of human anatomy to match the requirements of a surgical intervention through the oesophagus when considering an average size adult patient.

[0127] The identified joint parameters are 16 mm and 18 mm for joint diameter and joint length respectively. This allows two consecutive joints in a straight configuration to pass from the mouth cavity to the oesophagus. Once the input parameters are defined, an algorithm is used to compute the optimised joint parameters such as the rolling joint radius, the rolling joint width, and the tendon position. These parameters are then used to create a template rolling joint design which is automatically updated with the computed parameters and can be rapidly manufactured using 3D printing techniques.

[0128] The combination of the rolling joint 6 with the spur gears allows bi-stability and synchronous motion through the surgical instrument 2. The position and the arc of the two rolling joint parts is based on the spur gear parameters, so the rolling joint will match the pitch circle of the spur gears. This is to ensure a correct distance between two mated spur gears and to allow a smooth rolling action. If the rolling joint is too large, this will result in slack when two joint components are engaged with one another. If the rolling joint part is too small, this will result in jerky motion and instability as the teeth of each spur gear will collide with one another.

[0129] While the subject matter discussed herein is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the claims to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the claims.