WO2021175845A1

WO2021175845A1 - Retractor device for transoral insertion to a surgical site, and method of viewing a surgical site

Info

Publication number: WO2021175845A1
Application number: PCT/EP2021/055173
Authority: WO
Inventors: Christian CAMENZULI; Josef ATTARD; John Paul Borg; Jonathan C BORG; Pierre Schembri WISMAYER; Jean Calleja AGIUS
Original assignee: University Of Malta
Priority date: 2020-03-06
Filing date: 2021-03-02
Publication date: 2021-09-10
Also published as: GB2608526B; GB202212911D0; GB2608526A; GB202003311D0

Abstract

Retractor devices for transoral surgery are disclosed. In one arrangement, a device is provided having an integral endoscope or an endoscope receiving member for receiving an endoscope. A retractor arrangement is further provided. The retractor arrangement has an elongate body with a distal end and a proximal end. An expander member is provided at or adjacent to the distal end. A manually actuatable member is provided at or adjacent to the proximal end. A user can switch the expander member between a radially contracted state and a radially expanded state by manipulation of the manually actuatable member. The endoscope and the elongate body: extend along parallel or coincident longitudinal axes to a longitudinally intermediate position along the elongate body; and diverge from each other in the proximal direction from the longitudinally intermediate position.

Description

RETRACTOR DEVICE FOR TRANSORAL INSERTION TO A SURGICAL SITE, AND METHOD OF VIEWING A SURGICAL SITE

This invention relates to a retractor device for supporting transoral surgery, particularly transoral thyroid surgery.

The principals of the transoral approach to thyroid surgery see their origin in 2010 with anatomical studies that assessed the anatomical feasibility of this approach. The technique has since gained ground with systematic reviews showing that the technique is safe and feasible. See, for example, Camenzuli C, Schembri Wismayer P, Calleja Agius J (2018) Transoral Endoscopic Thyroidectomy: A Systematic Review of the Practice So Far. JSLS; and Camenzuli C, Schembri Wismayer P, Calleja Agius J (2018) Transoral Endoscopic Thyroidectomy: A Systematic Review of the Practice So Far. JSLS. Transoral thyroidectomy has been deemed superior to previous minimally invasive techniques since it offers effectively scarless surgery whilst keeping the anatomical dead-space between access and gland to a minimum.

An established technique for the transoral approach to thyroid surgery is known as transoral endoscopic thyroidectomy through a vestibular approach (TOETVA). This technique involves the use of carbon dioxide insufflation to keep the surgical space open and therefore allow good visualization during the procedure. Cases of carbon dioxide embolization with potentially lethal consequences secondary to this insufflation have been published. In addition, insufflation might lead to other, usually self-limiting complications. These include surgical emphysema and mediastinal emphysema. It is thought that the risk of such complications can be lessened by reducing the pressure and flow rate of carbon dioxide, but they are not eliminated.

A gasless modification to the transoral technique is known in which a working space is kept open by engaging the skin in the neck with Kirschner 1.2 mm wires and retracting on these ( Nakajo A, Arima H, Hirata M, Mizoguchi T, Kijima Y, Mori S, et al (2013); Trans-Oral Video- Assisted Neck Surgery (TOVANS). A new transoral technique of endoscopic thyroidectomy with gasless premandible approach. Surg Endosc. 27(4):1105-10). This technique is not completely scarless, however, since the wires need stab incisions in the skin to be engaged.

It is an object of the invention to provide an improved way of allowing the operating space to be kept open during thyroid surgery while avoiding use of gas. According to an aspect, there is provided a retractor device for transoral insertion to a surgical site, the device comprising: an integral endoscope or an endoscope receiving member configured to receive an endoscope; and a retractor arrangement, the retractor arrangement comprising: an elongate body having a distal end for insertion to a surgical site in a patient and a proximal end that remains outside of the patient during use; an expander member at or adjacent to the distal end of the elongate body, the expander member being switchable between a radially contracted state and a radially expanded state; and a manually actuatable member at or adjacent to the proximal end of the elongate body, the manually actuatable member being coupled to the expander member by an actuation mechanism that switching of the expander member between the radially contracted state and radially expanded state by manipulation of the manually actuatable member, wherein the device is configured such that the endoscope and the elongate body: extend along parallel or coincident longitudinal axes in a proximal direction from the expander member to a longitudinally intermediate position along the elongate body; and diverge from each other in the proximal direction from the longitudinally intermediate position.

The inventors have found that the device as thus configured allows an operator to insert the device with a high degree of control to a surgical site and reliably hold the surgical site open to allow viewing of the surgical site via an endoscope integral with the device or inserted through an integrated port (endoscope receiving member). The device does not require any gas-based mechanism to hold tissue open, nor external incisions of any kind (such as stab incisions). The divergence of axes of the endoscope and elongate body in the proximal direction enhances ease of use by provided greater leverage for a user holding the device, including in respect of small rotations or twists about the longitudinal axis of the device, as well as providing room for a sensor device to be attached to the endoscope at a similar distance from the surgical site to the manually actuatable member. Furthermore, the radial width of the device can be kept small for the portion of the device that will be within the body when the device is inserted to the surgical site, thereby minimizing the risk of injury caused by the device.

In an embodiment, the endoscope extends linearly from the expander member to at least a position that is as far from the expander member as the manually actuatable member. The linear path facilitates guiding of a 5mm 30 degree standard endoscope to allow visualisation. In an embodiment, a mechanical support member is provided that mechanically couples the endoscope to the elongate body at a position on a proximal side of the longitudinally intermediate position and spaced apart from the longitudinally intermediate position. The mechanical support member ensures that the rigidity of the device can be kept high while making the elongate body sufficiently thin to allow transoral access. It also allows the device and the endoscope to become one unit in embodiments where the endoscope is non-integral (i.e. received in an endoscope receiving member), which means the whole device can be manipulated safely with one hand if necessary (e.g. by an assistant of a primary surgeon). This may be important to allow the primary surgeon enough space to work without having the assistant in the way.

In an embodiment, the expander member comprises a plurality of fingers pivotably coupled to each other and the switching between the radially contracted state and the radially expanded state comprises rotation of the fingers about the pivotable couplings. This arrangement can be implemented reliably without requiring excessive bulk either at the expander member itself or in the actuation mechanism connecting the manually actuatable member to the expander member.

In an embodiment, the pivotable coupling is such that a plurality of the fingers rotate about a common axis of rotation. Arranging for the fingers to rotate about a common axis of rotation means that the fingers spread out within a common plane, which facilitates effective retraction of tissue and optical access to the surgical site. Preferably, the fingers have elongate cross-sections with axes of elongation perpendicular to the common axis of rotation. Thus, the fingers may be relatively flat in the plane in which they spread out, which further supports optimal tissue retraction and optical access.

In an embodiment, the expander member comprises a first finger, a second finger and a third finger; the first finger is fixed to be aligned with the longitudinal axis of the distal portion of the elongate body in the radially contracted state and in the radially expanded state; and the second and third fingers are pivotably coupled to each other so as to rotate in opposite directions about a common axis of rotation during switching of the expander member between the radially contracted state and the radially expanded state. This arrangement provides a highly robust and symmetrical expansion which can be implemented with minimal complexity and high reliability.

In one implementation, the number of fingers is three, for example with the above arrangement being provided with the first, second and third fingers described and no other fingers. The inventors have found that this approach provides an optimal balance of retraction points and mechanically solidity and compactness. The arrangement can be implemented with high rigidity without exceeding an outer diameter of 10mm, providing high performance without any increase in the size of incisions in the mouth being needed in comparison with standard alternative approaches.

The invention will now be further described, merely by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective view of a retractor device with an expander member in a radially expanded state;

Figure 2 is a schematic perspective view of the device of Figure 1 with the expander member in a radially contracted state;

Figure 3 is a schematic perspective view of a distal portion of the device of Figures 1 and

2, rotated by 180 degrees to show a distal end of an endoscope; and

Figure 4 is a schematic perspective view of a proximal portion of the device of Figures 1-

3.

Figures 1-4 depict a retractor device 1. The device 1 is configured to be suitable for transoral insertion to a surgical site. Dimensions of the device 1 (length and width) are thus suitable for insertion via the mouth. In the description that follows, the term distal is used to refer to features that are furthest from a user during use of the device 1 (i.e. within the body).

The term proximal is used to refer to features that are nearest to the user during use of the device 1 (i.e. outside of the body).

The device 1 may comprise an integral endoscope (e.g. fixedly attached to other elements of the device, such as to the elongate body 8 described below) or an endoscope receiving member 2 configured to receive an endoscope 4. In the particular example shown, the device 1 comprises an endoscope receiving member 2. The endoscope receiving member 2 may, for example, comprise a guiding member such as a cylindrical tube having an inner diameter slightly larger than an outer diameter of an endoscope 4 suitable for the intended surgery, such as a standard 5mm 30 degrees endoscope. When the device 1 is to be used, an endoscope 4 is inserted into the guiding member (e.g. along the cylindrical tube). Regardless of whether the endoscope is integral or inserted into an endoscope receiving member 2, the endoscope 4 is configured to receive light reflected from the surgical site. The endoscope 4 may also illuminate the surgical site. The endoscope 4 may comprise an optically transparent surface that faces the surgical site. One or more optical elements such as lenses may be provided. The endoscope 4 may further comprise one or more optical waveguides or optical fibres for guiding reflected light and/or illuminating light from/to the surgical site to a region outside of the body. The endoscope 4 may be connected to a sensor device 6 such as a CCD. The sensor device 6 may detect reflected light received by the endoscope 4 to provide a signal for generating a viewable image of the surgical site.

The device 1 further comprises a retractor arrangement. The retractor arrangement comprises an elongate body 8. The elongate body 8 has a distal end 8 A for insertion to a surgical site in a patient and a proximal end 8B that remains outside of the patient during use.

The retractor arrangement further comprises an expander member 10. The expander member 10 is positioned at or adjacent to the distal end 8 A of the elongate body 8. The expander member 10 is switchable between a radially contracted state and a radially expanded state. Switching into the radially contracted state makes the expander member 10 more compact in the radial direction (thinner), thereby facilitating insertion of the expander member 10 to the surgical site and minimising the size of any required incision within the mouth. Indeed, in embodiments of the present disclosure the expander member 10 is dimensioned to not exceed an outer diameter of 10mm in the radially contracted state, such that no increase in the size of an incision in the mouth will be needed in comparison with known alternative approaches for transoral thyroid surgery. The radially expanded state is suitable for pushing away tissue at the surgical site to improve a view of the surgical site by the endoscope 4. When viewed along a longitudinal axis of at least a portion of the elongate body 8 adjacent to the expander member 10, a radially maximal portion of the expander member 10 is nearer to the longitudinal axis when the expander member 10 is in the radially contracted state than when the expander member 10 is in the radially expanded state. A maximum outer diameter of the expander member 10 in the radially expanded state may, for example, be significantly larger than 10mm. Examples of the radially expanded and radially contracted states of the expander member 10 are shown in Figures 1 and 2 respectively. The retractor arrangement further comprises a manually actuatable member 12 at or adjacent to the proximal end 8B of the elongate body 8. The manually actuatable member 12 is coupled to the expander member 10 by an actuation mechanism. The actuation mechanism allows a user to switch the expander member 10 between the radially contracted state and radially expanded state by manipulation of the manually actuatable member 12. The actuation mechanism is configured such that forces and/or torques imparted by manipulation of the manually actuatable member 12 are transmitted to the expander member 10. The transmitted forces and/or torques cause the expander member 10 to switch from the radially expanded state to the radially contracted state or from the radially contracted state to the radially expanded state. In an embodiment, the manually actuatable member 12 comprises a rotatable handle. The rotatable handle is rotatable under manipulation by a user of the device 1 about a longitudinal axis of a portion of the elongate body 8 adjacent to the manually actuatable member 12. The rotatable handle may be provided with gripping portions (as shown) to facilitate reliable gripping of the rotatable handle by the user. Any of various suitable known mechanisms for transmitting forces and/or torques (including mechanisms for transforming rotary motion into linear motion and vice versa) may be used to achieve the desired actuation. In an embodiment, the actuation mechanism comprises one or more tensioning members extending from the manually actuatable member 12 to the expander member 10 and the manually actuatable member 12 is configured such that rotation of the rotatable handle transmits forces to the expander member 10 via the one or more tensioning members. The tensioning members may comprise one or more strings or wires for example.

The device 1 is configured such that the endoscope 4 (regardless of whether it is integral or provided in an endoscope receiving member 2 as shown in the figures) and the elongate body 8 extend along parallel or coincident longitudinal axes 14, 16 in a proximal direction from the expander member 10 (i.e. away from the surgical site) to a longitudinally intermediate position 18 along the elongate body 8. In the example shown in the figures, the longitudinal axis of the elongate body 8 is labelled 14 and the longitudinal axis of the endoscope 4 is labelled 16. In the example shown, the endoscope 4 and the elongate body 8 thus extend along substantially coincident (or nearly coincident) longitudinal axes 14, 16 up to the longitudinally intermediate position 18. The device 1 is further configured such that the endoscope 4 and the elongate body 8 diverge from each other in the proximal direction from the longitudinally intermediate position 18. Thus, a distance between the longitudinal axis 14 of the elongate body 8 and the longitudinal axis 16 of the endoscope 4 increases for at least a portion of a path along the longitudinal axis 14 of the elongate body 8 from the intermediate position 18 to the proximal end 8B of the elongate body 8.

In some embodiments, as exemplified in the figures, the endoscope 4 (regardless of whether it is integral or provided in an endoscope receiving member 2 as shown in the figures) extends linearly from the expander member 10 to at least a position that is as far from the expander member 10 as the manually actuatable member 12.

In some embodiments, as exemplified in the figures, the elongate body 8 comprises an elbow at the longitudinally intermediate position 18 where a longitudinal axis 14 of the elongate body 8 changes direction (i.e. changing, in the example shown, from being coincident with the axis 16 of the endoscope 4 to diverging from that axis).

It is preferable that the longitudinally intermediate position 18 is such that the expander member 10 can be brought to a surgical site suitable for transoral surgery while the longitudinally intermediate position 18 is inside the oral cavity or outside of the body. Thus, a portion of the device 1 that is within the body in use can be kept as thin as possible.

In an embodiment, the device 1 further comprises a mechanical support member 20 that mechanically couples (e.g. rigidly) the endoscope 4, preferably releasably in embodiments where the endoscope 4 is non-integrally provided in an endoscope receiving member 2, to the elongate body 8 at a position on a proximal side of the longitudinally intermediate position 18 and spaced apart from the longitudinally intermediate position 18. Spacing the position of coupling apart from the longitudinally intermediate position 18 increases rigidity, particularly with respect to twisting of the device 1 about a longitudinal axis.

In some embodiments, as exemplified in the figures, the expander member comprises a plurality of fingers 31-33. The fingers 31-33 may be pivotably coupled to each other via a pivotable coupling 22. The switching between the radially contracted state and the radially expanded state may then comprise rotation of the fingers 31-33 about the pivotable coupling 22. In some embodiments, as exemplified in the figures, the pivotable coupling 22 is such that a plurality of the fingers 31-33 rotate about a common axis of rotation 24. This causes the fingers 31-33 to spread out in a common plane. In such an embodiment, the fingers 31-33 preferably have elongate cross-sections (i.e. are relatively flat). Axes of elongation (i.e. long axes) of the fingers 31-33 are preferably perpendicular to the common axis of rotation 24 (i.e. such that the fingers are flat within the common plane). This arrangement minimizes a size of the expander member 10 in a direction of overlap of the fingers 31-33 (e.g. parallel to the axis 24 in the example shown)

In the example shown, the expander member 10 comprises three fingers 31-33, but fewer or more fingers may be provided if desired. The fingers 31-33 are configured such that the fingers 31-33 are more aligned in the radially contracted state (as depicted in Figure 2) than in the radially expanded state (depicted in Figures 1 and 3). In some embodiments, the fingers 31- 33 are all substantially aligned with each other (e.g. lying on top of one another, as in the example shown) in the radially contracted state. In an embodiment, the fingers 31-33 are pivotably coupled to each other at or near proximal ends of the fingers 31-33. In the example shown, the fingers 31-33 are pivotably coupled to each other so as to be rotatable about a common axis 24. The expander member 10 is configured to cause the fingers 31-33 to fan out to switch the expander member 10 from the radially contracted state to the radially expanded state. In the example shown, the switching comprises fingers 31 and 33 rotating in opposite directions about the axis 24.

In an embodiment, the expander member 10 comprises a first finger 31 , a second finger 32 and a third finger 33. The first finger 31 is fixed to be aligned with the longitudinal axis 14 of the elongate body 8 adjacent to the distal end 8 A in the radially contracted state and in the radially expanded state. The second and third fingers 32, 33 are pivotably coupled to each other so as to rotate in opposite directions about a common axis of rotation 24 during switching of the expander member 10 between the radially contracted state and the radially expanded state.

The device according to any of the embodiments described above may be used in methods for viewing a surgical site, in particular where the surgical site is for thyroid or other transoral endoscopic surgical procedures. Such methods may comprise inserting the device 1 orally to bring the expander member 10 of the device 1 to the surgical site. The device 1 may be inserted while the expander member 10 is in the radially contracted state. The expander member 10 is switched from the radially contracted state to the radially expanded state after the expander member 10 has reached the surgical site. The expander member 10 is used in the radially expanded state to displace tissue to improve a view of the surgical site. The endoscope of the device 1 or an endoscope in the endoscope receiving member 2 of the device 1 is used to detect reflected light from the surgical site to provide an image of the surgical site.

Demonstration of Efficacy

The following study was performed to demonstrate efficacy of the retractor device.

A team consisting of anatomists, engineers and a surgeon was established and the project was approved by the University of Malta ethics board committee. A retractor device according to the above description was provided. The device was made from non-toxic and non-conductive material to be safely used in humans. To remain as faithful to the scarless principle of TOETVA as possible, the device was configured to be introduced to its position through the vestibule of the mouth without the need for it to be inserted or otherwise stabilized in place through the use of skin incisions.

Three Thiel embalmed cadavers were used to reproduce the standard operative technique of TOETVA. This technique utilizes carbon dioxide at a pressure of 6mmHg to keep the operative space open. When the device was developed, the technique without gas insufflation was trialed in three Thiel embalmed cadavers using the otherwise standard technique for TOETVA except the insufflation. In all of the six cadavers, pictures were taken at the following three standard operative stages:

I. When the subplatysmal plane has been developed and the view showed the strap muscles divided by the intact linea alba cervicalis.

II. When the linea alba cervicalis has been opened, the thyroid isthmus has been dissected centrally off the trachea and being lifted on the working instrument.

III. When the thyroid isthmus has been divided centrally and the strap muscle dissected off the left thyroid lobe. The lobe is retracted supero-medially using a grasper.

The best available picture of each stage from the three cadavers with insufflation and the three cadavers with the gasless technique was chosen. The pictures were then sent to a panel of four specialists in thyroid surgery. Each specialist was asked to rank the visibility of structures on a visual analogue score of 1 to 10 were a score of 1 meant completely unidentifiable structures and score of 10 meant all structures identifiable with extreme ease. The specialists did not know to what group the picture being scored belonged two. The scores from the two groups were then statistically analysed using the Wilkoxin Rank test using IBM SPSS Statistics for Windows, Version 25 (Released 2017. Armonk, NY: IBM Corp.)

The cadavers utilized for this study were similar in both groups in terms of gender and neck dimensions. The most important difference between the two groups was the dissection times taken for the development of the subplatysmal space. Despite not being significantly longer in the gasless technique, using carbon dioxide insufflation helped in the dissection and made this step more efficient. Once this space was open, the working space offered by both techniques was sufficient for the operation to take place. The performing surgeon could identify the essential anatomical structures and the space offered in both techniques allowed enough space for the dissection to take place safely. After the procedure, all cadavers in whom carbon dioxide insufflation was used had surgical emphysema that extended up to middle part of the chest wall. The latter was absent in the gasless technique. Post procedural open assessment of the necks of the cadavers in this study revealed no unintended damage to surrounding structures in both techniques.

When the scores given by the panel at each stage for the two techniques were compared, the p value achieved was 1. The standard deviation for the mean scores given for the insufflation technique and gasless technique were similar at 1.7 and 2.2 respectively. Therefore for the panel of experts assessing the various stages, the two techniques were equivalent in their operative space and ability to identify anatomical structures.

The advancement of minimally invasive techniques is intrinsically linked with these practices offering a safety profile which is identical or superior to the gold standard. TOETVA has already deemed to be a safe procedure when compared to the conventional open thyroidectomy. Carbon dioxide insufflation was however found to offer a number of complications most of which self-limiting but occasionally life-threatening. Our group developed a technique that eliminates the need for gas insufflation altogether whilst remaining faithful to the scarless principals of TOETVA. The experimental implementation of the new device on cadavers has shown that when compared with the standard technique for TOETVA, the gasless alternative has equivalent safety profile. The device developed is aimed for the endoscopic variant of TOETVA but can be easily adapted to the robotic technique should the need for this arise.

Claims

1. A retractor device for transoral insertion to a surgical site, the device comprising: an integral endoscope or an endoscope receiving member configured to receive an endoscope; and a retractor arrangement, the retractor arrangement comprising: an elongate body having a distal end for insertion to a surgical site in a patient and a proximal end that remains outside of the patient during use; an expander member at or adjacent to the distal end of the elongate body, the expander member being switchable between a radially contracted state and a radially expanded state; and a manually actuatable member at or adjacent to the proximal end of the elongate body, the manually actuatable member being coupled to the expander member by an actuation mechanism that allows switching of the expander member between the radially contracted state and radially expanded state by manipulation of the manually actuatable member, wherein the device is configured such that the endoscope and the elongate body: extend along parallel or coincident longitudinal axes in a proximal direction from the expander member to a longitudinally intermediate position along the elongate body; and diverge from each other in the proximal direction from the longitudinally intermediate position.

2. The device of claim 1 , wherein the endoscope extends linearly from the expander member to at least a position that is as far from the expander member as the manually actuatable member.

3. The device of claim 1 or 2, wherein the elongate body comprises an elbow at the longitudinally intermediate position where a longitudinal axis of the elongate body changes direction.

4. The device of any preceding claim, wherein the longitudinally intermediate position is such that the expander member can be brought to a surgical site suitable for thyroid surgery while the longitudinally intermediate position is inside the oral cavity of a patient or outside of the body of the patient.

5. The device of any preceding claim, further comprising a mechanical support member configured to mechanically couple the endoscope to the elongate body at a position on a proximal side of the longitudinally intermediate position and spaced apart from the longitudinally intermediate position.

6. The device of any preceding claim, wherein the manually actuatable member comprises a rotatable handle configured to be rotatable under manipulation by a user of the device about a longitudinal axis of a portion of the elongate body adjacent to the manually actuatable member.

7. The device of claim 6, wherein the actuation mechanism comprises one or more tensioning members extending from the manually actuatable member to the expander member and the manually actuatable member is configured such that rotation of the rotatable handle transmits forces to the expander member via the one or more tensioning members.

8. The device of any preceding claim, wherein the expander member comprises a plurality of fingers pivotably coupled to each other and the switching between the radially contracted state and the radially expanded state comprises rotation of the fingers about the pivotable couplings.

9. The device of claim 8, wherein the pivotable coupling is such that a plurality of the fingers rotate about a common axis of rotation.

10. The device of claim 9, wherein the fingers have elongate cross-sections with axes of elongation perpendicular to the common axis of rotation.

11. The device of any of claims 8-10, wherein: the expander member comprises a first finger, a second finger and a third finger; the first finger is fixed to be aligned with the longitudinal axis of the elongate body adjacent to the distal end in the radially contracted state and in the radially expanded state; and the second and third fingers are pivotably coupled to each other so as to rotate in opposite directions about a common axis of rotation during switching of the expander member between the radially contracted state and the radially expanded state.

12. The device of any of claims 8-11, wherein the fingers are pivotably coupled to each other at or near proximal ends of the fingers.

13. The device of any of claims 8-12, wherein the number of fingers is three.

14. The device of any preceding claim, dimensioned to be suitable for insertion to a surgical site via the mouth, preferably wherein the surgical site is suitable for performing thyroid surgery.

15. A method of viewing a surgical site, preferably a surgical site for thyroid surgery, the method comprising: inserting the device of any preceding claim orally to bring the expander member of the device to the surgical site, while the expander member is in the radially contracted state; switching the expander member from the radially contracted state to the radially expanded state after the expander member has reached the surgical site; using the expander member in the radially expanded state to displace tissue to improve a view of the surgical site; and using the endoscope to detect reflected light from the surgical site to provide an image of the surgical site.