GB2582320A

GB2582320A - Shaft component for a surgical instrument

Info

Publication number: GB2582320A
Application number: GB1903714.2A
Authority: GB
Inventors: Hoodless Richard
Original assignee: Gyrus Medical Ltd
Current assignee: Gyrus Medical Ltd
Priority date: 2019-03-19
Filing date: 2019-03-19
Publication date: 2020-09-23
Anticipated expiration: 2039-03-19
Also published as: GB201903714D0; GB2582320B

Abstract

A shaft component 52 for a surgical instrument, component 52 comprising: first and second ends 58&56 that are respectively distal and proximal to an end effector 424 of the surgical instrument; and a tubular body between first and second ends 58&56 that permit’s torsional elastic deformation of the tubular body about a longitudinal axis of the surgical instrument under a loading torque, the end effector being elastically rotatable with respect to the first end 58. Preferably the tubular body comprises two axially arranged sections with an arm 524 extending axially between them enabling torsional elastic deformation of the tubular body about the surgical instrument’s longitudinal axis under the loading torque. Arm 524 may be formed between two slots 522&524, where each slot 522&524 may comprise first & second portions, the first portion being orthogonal to surgical instrument’s longitudinal axis and the second portion being parallel to the surgical instrument’s longitudinal axis, the two slots 522&524 being interdigitated. Also a surgical instrument comprising a shaft component 52. Described application in instruments with an inner blade 54 rotating in a tube 42, where torsional elastic deformation of component 52 reduces impact damage caused by debris trapped between blade & tube 54&42.

Description

SHAFT COMPONENT FOR A SURGICAL INSTRUMENT

Technical Field

Embodiments of the present invention described herein relate to surgical devices, and in particular to a shaft component for a surgical instrument.

Background to the Invention and Prior Art

Surgical instruments, including radio frequency (RF) shaver electrosurgical instruments, in which an elongate inner tube is rotated within an elongate, tubular outer tube, have become well accepted in surgical procedures where access to the surgical site is restricted to a narrow passage, for example, in minimally invasive "keyhole" surgeries.

Combination RF shaver electrosurgical instruments comprise an electrode and shaver component, allowing one instrument to be used for both cutting and coagulation. Typically, in a combination RF shaver electrosurgical instrument, the end effector may be composed of a rotating metal blade tube housed within an outer tube having a distal ceramic outer component.

In the event of the rotating blade trapping a foreign body (e.g., bone debris or other surgical instrument) between the blade edge and the ceramic edge, the energy stored in the distal blade shaft would be transferred via the foreign body to the ceramic edge. This would occur even if the motor or other drive inertia was decoupled from the end effector by, for example, a break pin, clutch or flexible coupling. This energy transfer to the ceramic edge may result in impact damage and ultimately failure of the ceramic component.

A difficulty in resolving this challenge results from the fact that the shaft is a tube and its inner and outer diameters must be unaffected by any such solution, due to space constraints.

A prior art arrangement is known from US 2002/0038129 Al, which discloses a flexible inner tubular member for being rotated in an outer tubular member of a rotary tissue cutting instrument. This includes an elongate inner tube having a rotatably driveable proximal end, a distal end having a cutting member exposed from the outer tubular member to cut anatomical tissue, and a flexible region allowing the inner tubular member to rotate within the outer tubular member while conforming to the shape of the outer member. The flexible region is defined by a helical cut in the inner tube defining a plurality of integrally, unitarily connected tube segments angularly movable relative to one another and a spiral wrap disposed over the helical cut.

Another prior art arrangement is known from US 2013/0261628 Al, which discloses a flexible drill bit comprising a proximal shaft portion for connecting to a source of turning; a distal cutting tip portion for boring into a material; and an intermediate shaft portion extending between the proximal shaft portion and the distal cutting tip portion, the intermediate shaft portion being characterized by (i) sufficient longitudinal flexibility so as to permit the flexible drill bit to be passed along a curve, and (ii) sufficient torsional strength to permit the flexible drill bit to bore into the material.

Summary of the Invention

Embodiments of the present invention provide an improved surgical instrument having a torsionally deformable shaft component within the inner blade shaft, adjacent to an end effector of the surgical instrument. The shaft component comprises a tubular body portion comprising a configuration of one or more arms which allow the tubular body portion to torsionally deform in an elastic manner under a loading torque. A surgical instrument may he composed of a rotating inner blade tube housed within an outer tube having a ceramic component. In the event of a foreign body (e.g., bone debris or another surgical instrument) becoming trapped between the inner blade tube and the outer ceramic component, damage may occur to the ceramic component. In use, the shaft. component prevents this damage by allowing torsional elastic deformation, providing a degree of flexibility to the shaft. This minimises the rate of change of momentum of the shaft inertia to the ceramic component, thereby reducing the risk for impact loading damage.

In view of the above, in a first aspect the present invention provides a shaft component for a surgical instrument, comprising: a first end, distal to an end effector of the surgical instrument; a second end, proximal to the end effector; and a tubular body portion between the first end and the second end adapted to permit torsional elastic deformation of the tubular body portion about a longitudinal axis of the surgical instrument under a loading torque, whereby the end effector is elastically rotatable with respect to the first end.

Such an arrangement improves upon the known surgical instrument arrangements of the prior art by allowing torsional flexibility of the shaft, as opposed to the longitudinal flexibility that the prior art describes. Torsional flexibility can limit damage caused by foreign body impacts with the surgical instrument. The prior art aims to allow longitudinal flexibility whilst maximising torque transmission (i.e., maximising torsional stiffness), whereas the present invention's purpose is to introduce an element with reduced torsional stiffness to increase torsional flexibility.

In one embodiment the arrangement is such that the tubular body portion comprises two axially arranged sections and at least one arm extending axially between the two axially arranged sections, arranged to enable torsional elastic deformation of the tubular body portion about the longitudinal axis of the surgical instrument under a loading torque. Such an arrangement allows the tubular body portion to torsionally deform in an elastic manner under a loading torque applied by a foreign body impact with the surgical instrument.

In one embodiment the arrangement is such that the at least one arm is formed between at least two slots. The at least two slots may comprise at least a first portion and a second portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, the second portion being substantially parallel to the longitudinal axis of the surgical instrument, wherein the at least two slots are interdigitated.

In one embodiment the arrangement is such that the tubular body portion comprises at least two arms formed between at least two slots. A first slot of the at least two slots may comprise a first portion and a second portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, and the second portion being substantially parallel to the longitudinal axis of the surgical instrument; and a second slot of the at least two slots may comprise a first portion, a second portion and a third portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, the second and third portions being substantially parallel to the longitudinal axis of the surgical instrument; wherein the at least two slots are interdigitated.

In one embodiment the arrangement is such that the tubular body portion comprises at least five arms formed between at least two slots. Each of the at least two slots may comprise at least a first portion, a second portion, a third portion and a fourth portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, and the second, third and fourth portions being substantially parallel to the longitudinal axis of the surgical instrument, wherein the at least two slots are interdigitated.

The three embodiments described above have differing levels of torsional flexibility, allowing differing degrees of torsional deformation. By altering the shape of the one or more slots during manufacturing, the desired level of torsional stiffness can be achieved.

The at least one arm may define a first arm pattern, and the tubular body portion may comprise multiple arm patterns, the multiple arm patterns being distributed circumferentially around the tubular body portion.

Such an arrangement of having multiple arm patterns allows greater torsional flexibility than having only one of the said arm patterns. Varying the number of arm patterns during manufacturing provides another way to achieve the desired level of torsional stiffness.

Another aspect of the present disclosure provides a surgical instrument, comprising: a hand-piece; and an operative shaft, comprising: an end effector portion, distal to the hand-piece; a shaft portion, proximal to the hand-piece; and an intermediate portion between the end effector portion and the shaft portion, comprising a shaft component as described above, wherein the shaft component is less torsionally stiff than the distal end effector portion and the proximal shaft portion.

A further aspect provides an arrangement wherein the surgical instrument as described above is an electrosurgical instrument, and wherein the operative shaft comprises RF electrical connections, drive componentry for the end effector portion, the end effector portion comprising at least one active electrode, the rotary shaver arrangement being operably connected to the drive componentry to drive the rotary shaver to operate in use, and the active electrode being connected to the RF electrical connections.

A yet further aspect provides an electrosurgical system, comprising: an RF electrosurgical generator; a suction source; and an electrosurgical instrument as described in the above aspect.

Brief Description of the Drawings

Embodiments of the invention will now he further described by way of example only and with reference to the accompanying drawings, wherein like reference numerals refer to like parts, and wherein: Figure 1 is an end view of a foreign body impact at the tip of an electrosurgical instrument, demonstrating the problem to be solved in the prior art.

Figure 2 is a side view of an electrosurgical instrument.

Figure 3 is a schematic diagram of an electrosurgical system including an electrosurgical instrument according to an embodiment of the present invention.

Figure 4 is a perspective view of an electrosurgical instrument according to an embodiment of the present invention.

Figure 5 shows plan views of three example arm configurations.

Figure 6 shows a side view of the distal end of the shaft.

Description of the Embodiments

Referring to the drawings, Figures 1 and 2 demonstrate the problem to be solved in the prior art. Figure 1 shows the end view of a foreign body impact at the tip of an RF shaver. If a foreign body, such as bone debris 100 or another surgical instrument 120, becomes trapped between the inner blade shaft 140 and the outer ceramic shaft 160, the energy stored in the blade shaft 140 will be transferred via the trapped foreign body 100, 120 to the ceramic component 160. This energy may result in impact damage and potentially failure of the ceramic component 160.

Figure 3 shows electrosurgical apparatus including an electrosurgical generator 1 having an output socket 2 providing a radio frequency (RF) output, via a connection cord 4, for an electrosurgical instrument I 2. The instrument 12 has irrigation and suction tubes 14 which are connected to an irrigation fluid and suction source 10. Activation of the generator 1 may be performed from the instrument 12 via a hands witch (not shown) on the instrument 12, or by means of a footswitch unit 5 connected separately to the rear of the generator 1 by a footswitch connection cord 6. In the illustrated embodiment, the footswitch unit 5 has two footswitches 5a and 5b for selecting a coagulation mode or a cutting or vaporisation mode of the generator 1 respectively. The generator front panel has push buttons 7a and 7b for respectively setting cutting or coagulation power levels, which are indicated in a display 8. Push buttons 9 are provided as an alternative means for selection between the cutting and coagulation modes.

Figure 4 shows an clectrosurgical instrument 12. The instrument 12 includes a proximal handle portion 44, a hollow shaft 42 extending in a distal direction away from the proximal handle portion, a torsionally deformable shall component 52, and a distal end effector assembly 424 at the distal end of the shaft 42. A power connection cord 4 connects the instrument to the RF generator 1, whereas tubes 14 connect the instrument to the irrigation and suction source 10. The instrument may further be provided with activation buttons (not shown), to allow the surgeon operator to activate either the mechanical cutting function of the end effector, or the clectrosurgical functions of the end effector.

Figures 5 and 6 show the shaft component 52 in more detail. The shaft component 52 is formed towards the distal end 422 of the existing inner blade shaft 54. The shaft component 52 has a first end 58, distal to the end effector 424, and a second end 56, proximal to the end effector 424. The shaft component 52 may be integrated into the inner blade shaft 54 or he a separate component which can he inserted into the inner blade shaft 54. The material from which the inner blade shaft shall 54 is fabricated may be some sort of steel having high fatigue life properties, or alternatively another suitable material with high fatigue life characteristics such as Nitinol. The shaft component 52 is designed such that it is adapted to permit torsional elastic deformation of the tubular body portion about a longitudinal axis of the surgical instrument under a loading torque, whereby the end effector is elastically rotatable with respect to the first end of the shaft component 58. By elastic deformation' we mean macroscopic elastic deformation, i.e., the shaft component 52 as a whole is deformable, but reverts back to its original shape once the loading torque is no longer acting upon it. By 'elastically rotatable' we mean that the end effector 424 can be rotated relative to the first end of the shaft component 58, but will revert back to its original position once the loading torque is no longer applied. The shaft component' s torsional elastic deformation minimises the rate of change of momentum (impulse) of the shall 54 inertia to the distal ceramic component 62, thereby reducing the potential for impact loading damage.

A number of arm configurations are possible, with three examples shown in Figures 5a, 5b and 5c. Figure 5a shows a one arm 524 configuration of the shaft component 52 with two interdigitated L-shaped slots 522, 526. Interdigitated' refers to way the L-shaped slots 522, 526 are positioned so that the base portions of the L-shapes 522, 526 are parallel and adjacent to one another. 'Arm' refers to the portion of the shaft component between the two parallel base portions. The shaft component 52 may be seen to comprise two axially arranged sections, the arm extending axially between the two sections. Figure 5b shows a two arm 524 configuration with one T-shaped slot 522 interdigitated with one F-shaped slot 526. Figure 5c shows a five arm 524 configuration with two interdigitated m-shaped slots 522, 526. Conceivably there could be arm configurations with three or four arms, or more than five arms.

Arm 524 properties, e.g., number, length and thickness, may be adjusted to give the appropriate torsional stiffness. The arms 524 may be produced by laser cutting, electro-discharge machining, water cutting, plasma cutting, or any other suitable cutting method. Fatigue of the arms 524 could he managed by increasing the thickness and the number of the arm elements 524, thereby maintaining a similar torsional stiffness. There may he single or multiple arm patterns arranged circumferentially around the shaft component 52. An arm pattern refers to a set of one or more arms which may he repeated as a set. The base of each slot formed by the arms or the base of the arms themselves has a radius profile to minimise stress concentrations, thereby minimising stress and therefore improving the life of the component, which would be subject repeated cycling stresses. The shaft component 52 reduces torsional stiffness of the inner shaft 54. This is not problematic from a normal tissue cutting perspective as this cutting relies on rotational displacement of the inner blade shaft 54 with respect to the outer shaft 62.

Eventually the blade will rotate past the cutting position regardless of the torsional stiffness of the inner shaft 54.

In the main embodiment, torsional flexibility is achieved mechanically by introducing interdigitated patterns of slots to form arms in a portion of the inner blade tube. However, other arrangements of arms could he used to achieve a similar effect.

Torsional flexibility could also he achieved by inserting a torsionally flexible material which can deform elastically, for example, rubber, or any elastic polymeric material, into the shaft. The main embodiment is advantageous because the slotted portion can be integrated into the inner blade tube, therefore requiring less individual parts.

Various modifications whether by way of addition, deletion, or substitution of features may be made to above described embodiment to provide further embodiments, any and all of which are intended to be encompassed by the appended claims.

Claims

Claims 1. A shaft component for a surgical instrument comprising: a first end, distal to an end effector of the surgical instrument; a second end, proximal to the end effector; and a tubular body portion between the first end and the second end adapted to permit torsional elastic deformation of the tubular body portion about a longitudinal axis of the surgical instrument under a loading torque, whereby the end effector is elastically rotatable with respect to the first end.
2. The shaft component according to claim 1, wherein the tubular body portion comprises two axially arranged sections and at least one arm extending axially between the two axially arranged sections, arranged to enable torsional elastic deformation of the tubular body portion about the longitudinal axis of the surgical instrument under a loading torque.
3. The shaft component according to claim 2, wherein the at least one arm is formed between at least two slots.
4. The shaft component according to claim 3, wherein each of the at least two slots comprise at least a first portion and a second portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, the second portion being substantially parallel to the longitudinal axis of the surgical instrument, wherein the at least two slots are interdigitated.
5. The shaft component according to claim 2, wherein the tubular body portion comprises at least two arms formed between at least two slots.
6. The shaft component according to claim 5, wherein: a first slot of the at least two slots comprises a first portion and a second portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, and the second portion being substantially parallel to the longitudinal axis of the surgical instrument; and a second slot of the at least two slots comprises a first portion, a second portion and a third portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, the second and third portions being substantially parallel to the longitudinal axis of the surgical instrument; wherein the at least two slots are interdigitated.
7. The shaft component according to claim 2, wherein the tubular body portion comprises at least five arms formed between at least two slots.
8. The shaft component according to claim 7, wherein each of the at least two slots comprise at least a first portion, a second portion, a third portion and a fourth portion, the first portion being substantially orthogonal to the longitudinal axis of the surgical instrument, and the second, third and fourth portions being substantially parallel to the longitudinal axis of the surgical instrument, wherein the at least two slots are interdigitated.
9. The shaft component according to any of the claims 2-8, wherein the at least one arm defines a first arm pattern, and wherein the tubular body portion comprises multiple arm patterns, the multiple arm patterns being distributed circumferentially around the tubular body portion.
10. A surgical instrument, comprising: a hand-piece; and an operative shaft, comprising: an end effector portion, distal to the hand-piece; a shaft portion, proximal to the hand-piece; and an intermediate portion between the end effector portion and the shaft portion, comprising a shaft component according to any of the preceding claims, wherein the shaft component is less torsionally stiff than the distal end effector portion and the proximal shaft portion.
11. The surgical instrument of claim 10, wherein the surgical instrument is an electrosurgical instrument, and wherein the operative shaft comprises RF electrical connections, drive componentry for the end effector portion, the end effector portion comprising at least one active electrode, the rotary shaver arrangement being operably connected to the drive componentry to drive the rotary shaver to operate in use, and the active electrode being connected to the RF electrical connections.
12. An electrosurgical system, comprising: an RF electrosurgical generator; a suction source; and an electrosurgical instrument according to claim 11.