WO2019113638A1

WO2019113638A1 - Retractor

Info

Publication number: WO2019113638A1
Application number: PCT/AU2018/051319
Authority: WO
Inventors: Antonio DI IEVA
Original assignee: Macquarie University
Priority date: 2017-12-11
Filing date: 2018-12-11
Publication date: 2019-06-20

Abstract

An unmounted insertable retractor for separating anatomical structures during surgery, anatomical investigations or the like, the retractor having a body with a passage therethrough, the body configured to be placed between anatomical structures to be separated.

Description

RETRACTOR

Field of the Invention

[001] The present invention relates to retractors for separating anatomical structures during surgery, anatomical investigations or the like, and, in particular, to unmounted insertable retractors.

Background of the Invention

[002] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[003] Retractors are used for the separation of anatomical structures (e.g. connective tissue, muscle tissue, organs etc.) during invasive surgery and other medical procedures. They provide surgeons with an access pathway /corridor to sites or lesions that may be deep below the skin surface.

[004] Retractors can vary in shape and size depending on their application. For example, surgical access to deep-seated foreign bodies (e.g. bullets) or bleeding, or to deep-seated brain lesions such as tumours, abscesses or vascular lesions in the basal ganglia, or in the central core of the brain parenchyma, requires the use of specially designed brain retractors. Typical brain retractors comprise one or more rigid/semi-rigid metallic blades mounted to a support frame. The support frame may, for example, be stand alone, skull mounted, table mounted, or head rest mounted. In use, a surgeon typically adjusts the positioning of the mounted blades, to pry apart the brain tissue. The blades may be mounted to flexible“snake” arms, or may have screw type adjustment mechanism.

[005] Fixed/mounted retractors with rigid metallic blades have several disadvantages. One disadvantage is that they can cause vascular injury/compression of blood vessels and/or direct injury to the brain tissue, particularly at their edges. To reduce these risks, the blades often need to be released/adjusted during surgery. This can be troublesome for the surgeon, particularly during more complex surgical procedures where time is an important factor.

[006] Other forms of retractors that have been implemented for neurosurgical applications are those of the conical/tubular type. Whilst these conical/tubular retractors provide elongate protected pathways for surgical instruments, they still have problems similar to blade retractors in that they are generally rigid, and require mounting to a support frame, or to be held by the surgeon.

[007] Due to the risks/difficulties associated with using the above described brain retractors, retractor-less surgery is sometimes preferred. In such instances, a surgeon dynamically retracts the brain tissue with a surgical suction device or other surgical instruments. However, retractor-less surgery is generally not effective for deeper seated lesions or big tumours, as the surrounding brain tends to occlude the surgical cavity as soon the lesions begin to be debulked.

[008] The present invention seeks to address some of the above mentioned disadvantages of conventional retractors, and, in particular, neurosurgical retractors.

Summary of the Invention

[009] In one broad from, the present invention provides, an unmounted insertable retractor for separating anatomical structures during surgery, anatomical investigations or the like, the retractor having a body with a passage therethrough, the body configured to be placed between anatomical structures to be separated.

[0010] In one form, the body includes opposite outward facing contact portions for contacting the anatomical structures to be separated. In one form, the contact portions are edgeless.

[0011] In one form, the body is configured such that the separation distance as provided between opposing contact portions is greater than the passage length. In one form, the passage extends along a substantially linear axis, between a passage inlet and a passage outlet.

[0012] In one form, the body is conformable to the anatomical structures to be separated. In one form, the body is compressible yet resilient. In one form, the body is substantially non-compressible.

[0013] In one form, the body is inflatable. In one form, the body is configured to be inflatable to a state where the body is conformable to the anatomical structures to be separated. In one form, the body is configured to be inflatable to a state where the body is compressible yet resilient. In one form, the body is configured to be inflatable to a state where the body is substantially not compressible.

[0014] In one form, the body is inflatable to: a first functional state, wherein the inflated body is conformable to the anatomical structures to be separated; a second functional state, wherein the inflated body is compressible yet resilient; and a third functional state, wherein the inflated body is substantially not compressible.

[0015] In one form, the retractor configured to allow dynamic inflation/deflation. In one form, the retractor, includes a valve that permits dynamic inflation/deflation.

[0016] In one form, the shape of body is substantially toroidal. In one form, the body is substantially torus shaped. In one form, the entire outer surface of the body is substantially smooth.

[0017] In one form, the body is configured such that the dimensions of the passage are fixed. In one form, the body includes a rigid support portion around the passage so as to substantially maintain the dimensions of the passage. In one form, the retractor includes a rigid support structure around the passage so as to substantially maintain the dimensions of the passage. In one form, the rigid support structure is located within the body.

[0018] In one form, the body formed of a substantially transparent material. [0019] In one form, the body is formed of a polymer material. In one form, the body is formed of an elastomeric material. In one form, the body is formed of silicone.

[0020] In one form, the retractor is configured for separating brain tissue.

[0021] In a further broad form, the present invention provides a method of separating brain tissue during surgery, anatomical investigations or the like, including placing a retractor as described herein between brain tissue to be separated.

Brief description of the Drawings

[0022] The invention may be better understood with reference to the figure in which:

Figure 1 is a one example of a retractor according to the invention, particularly suited for use within brain parenchyma.

Detailed Description

[0023] Embodiments of the invention provide an unmounted insertable retractor for separating anatomical structures during surgery, anatomical investigations or the like. The retractor has a body with a passage therethrough, the body being configured to be placed between anatomical structures to be separated. Accordingly, the passage may allow visualisation of deep structures/lesions and can act as guide for surgical instruments. It will be appreciated that anatomical structures may include any part of the patient body (human or animal) such as, for example, connective tissue, muscle tissue or organ tissue etc.

[0024] Being unmounted and insertable, the retractor is able to be fully inserted into the patient between anatomical structures. A surgeon does not need to configure a mount/frame or hold the retractor in place with their hands. The retractor is essentially wedged between anatomical structures, separating them, allowing access for surgical instruments and visualisation of deep structures/lesions. The tendency of the structures to return to their natural position assists with secure location of the retractor. It will be appreciated that, once inserted, the retractor moves with the patient. This provides advantages in that injury/damage due to unintended movement of the patient is minimised. [0025] The body of the retractor typically includes opposite outward facing contact portions for contacting the anatomical structures to be separated. Typically, the contact portions are smooth/edgeless so as to reduce the likelihood of injury or damage to the anatomical structures, which may be sensitive organ tissue. It will be appreciated that the tendency for anatomical structures to return to their normal positon can be significant, and any edges in the contact portions may result in areas where increased pressure is applied against the anatomical structures. Therefore, it will be appreciated that the absence of edges in the contact portions reduces the risk of injury/damage to the anatomical structures to be separated. In some forms, the entire outer surface of the body is substantially smooth/edgeless.

[0026] Typically, the passage extends along a substantially linear axis, between a passage inlet and a passage outlet. In some forms, the body is configured such that the separation distance as provided between opposing contact portions is greater than the passage length. In such forms, it will be appreciated that the body is not elongate in the direction of the length of passage. This allows instruments inserted through the retractor passage to move more freely and to have access to a larger area at the passage outlet when compared to forms where the body is more elongate the direction of the length of the passage. For example, the angle of entry for instruments (with respect to the plane of the passage inlet) may be smaller so as to permit access to more area at the outlet (e.g. beyond and lateral to the passage outlet, as well as in line with the passage outlet). Other, more elongate corridors, such as those provided by prior art conical or tubular retractors, typically only provide access to a more limited area at the passage outlet, as movement of the surgical instruments/tools is restricted due to abutment with the passage walls.

[0027] It will be appreciated that the body may be provided in different forms having different characteristics suitable for different applications. In one form, the body may be conformable or malleable, such that when placed between anatomical structures to be separated, the malleability/conformability of the body allows the contact portions of the body to substantially conform to the shape of the structures. In another form, the body may be compressible/conformable yet resilient. In such forms the resilient nature of body may further facilitate secure location of the retractor between anatomical structures to be separated. When compressed, the expansion force of the body as provided by its resilient nature can act to more securely wedge the body between the structures. In yet a further form, the body may be substantially incompressible. This form may be useful when separating more durable structures or when greater separation distances are required.

[0028] Typically, the body of the retractor is inflatable. This provides that a single body may be used to provide the functionality of multiple forms, for different applications. For example, the body may be inflated to a first functional state where the body is conformable /malleable, further inflated to a second functional state where the body is compressible/conformable yet resilient, and yet further inflated to third functional state wherein the body is substantially non-compressible. Generally, the retractor body is dynamically inflatable/deflatable during a medical procedure/investigation. Typically the retractor includes a valve that permits dynamic inflation/deflation of the body. The valve is typically disposed on a face of the body oriented away from most anatomical structures in use, i.e. the top face of the body, so as not to contact any anatomical structures or interfere with the positioning of the retractor. It will be appreciated that the body may be inflated with a range of fluids, such as, for example, air or water. Typically, the body is inflated with saline solution.

[0029] The body may also be configured such that the dimensions of the passage are fixed. This provides that in instances where the body is compressed/conformed, the passage dimensions are maintained, so that the surgical access corridor is not compromised. It will be appreciated that the dimensions of the passage may be maintained in a variety of ways. In one example, the material of the body around the passage portion may be more rigid than the remainder of the body. For example, the material of the body around the passage may be less elastic and/or less flexible than the remainder of the body, for example by being thicker than the material in the remainder of the body or by any other suitable means. The material of the body may advantageously retain a degree of flexibility and/or compressibility, to allow tools which are inserted through the passage during use to be oriented at a wider range of angles by pressing into the passage walls. In other examples, the retractor may include a rigid support structure around the passage so as to substantially maintain the dimensions of the passage. The rigid support structure may, for example, be a metallic ring/cylinder incorporated within the body, around the passage.

[0030] In embodiments wherein material of the body around the passage is less elastic/flexible than the remainder of the body, the body may be formed such that there is a gradient in the elasticity and/or flexibility between the material of the body in the region of the passage and the material of the body in the region of the contact portions. When such a body is inflated, the elasticity and/or flexibility differential minimises expansion in the region of the passage whilst allowing greater inflation and expansion in the region of the contact portions, in a direction away from the passage, such that the retractor is able to expand and effectively separate the surrounding anatomical structures whilst minimising reduction in the size of the passage. Expansion may thus be biased in the direction of retraction and the size of the passage maximised. In a body which is torus or donut shaped as described above, a gradient may be present between the inner diameter and the outer diameter of the torus. Such a gradient may be present across substantially the whole body, or the gradient may be present only across portions of the body. The gradient may vary across the body of the retractor.

[0031] It will be appreciated that the body may be provided in a range of shapes, sizes and materials depending on the application required. Generally, the body has a substantially toroidal shape. Typically, the body is torus or donut shaped. It will be appreciated that in different forms, a torus or toroidal shaped body may have varying outer and inner diameter combinations/ratios. In some embodiments, the body may be torus shaped and the ratio between the inner diameter (i.e. the diameter of the ring defining the passage) and the outer diameter may be about 1:4. In some embodiments, the ratio is about 1:4 or lower, for example about 1:3, about 1:2, about 1:1.5 or about 1:1.3. The skilled person will appreciate that many ratios will be practicable depending on the use of the retractor. In some embodiments, the body is torus shaped and has an inner diameter of about 5mm and an outer diameter of about l5mm. The body of the retractor may be provided in a variety of sizes for different intended uses. In an embodiment, the internal diameter may be about 15 mm and the outer diameter may be about 25mm. In further exemplary embodiments, the inner diameter may be about 20 mm, about 25 mm, about 30 mm, about 35mm. In such embodiments, the outer diameters may be, for example, from about 25 mm to about 30 mm, from about 30 mm to about 35 mm, from about 35 mm to about 40 mm, and from about 40 mm to about 45 mm respectively.

[0032] Generally, the body is formed principally of a polymer material. The material of the body may have substantial elasticity so as to allow over inflation (where the material is stretched), or may be selected so as to have limited elasticity so as to limit over inflation. In one form, the body is formed of an elastomeric material. In one form, the body is formed of silicone. In another form, the body is formed of latex. In some forms, the body is formed from rubber. In some embodiments, the material from which the body is formed is advantageously thin, for example having a thickness of less than 2 mm, for example less than lmm, for example less than 0.5 mm The material may have a thickness of, for example, from about 0.1 mm to about 0.5 mm, for example from about 0.1 mm to about 0.35 mm. The material from which the body is formed is advantageously flexible. The desired flexibility of the material may be achieved by varying a number of factors, for example the thickness of the material, the durometer value of the material, the operation temperature, and the addition of additives to the material. For example, the body may be constructed from silicon or latex of durometer Shore A40. The material from which the body is constructed may also advantageously be of uniform thickness for ease of construction and controllable expansion across the body when the body is inflated. The body may be constructed by adhering the material into the desired shape, for example using adhesive or by welding, for example by radio frequency welding. For example, two complementary sheets of material may be adhered at their edges to form the body.

[0033] The material of the body may also be substantially transparent. This provides that the surgeon (or other person) is able to view anatomical structures behind the retractor or to detect damage occurring at the contact interface between the retractor and the structures being separated. For example, any bleeding occurring between the retractor and separated structures may be identified promptly. The material of the retractor is also typically of a nature that minimises occurrences of damage/injury due to friction between the contact portions and the structures. It will be appreciated that several methodologies may be implemented to reduce friction, including forming the body of an appropriate material, having smooth contact portions, or having contact portions that more readily form lubricating films thereon.

[0034] The retractors as described herein are generally disposable, however, in some forms, they may be embodied as reusable devices. It will also be appreciated that the retractors as described in herein may be utilised for a range of different applications and medical procedures. One particularly suitable application is in the separation of brain tissue. Thus one method of separating brain tissue during surgery, anatomical investigations or the like, includes placing a retractor as described herein between brain tissue to be separated.

[0035] Figure 1 shows one particular example of a retractor (1) according to the invention. The retractor (1) is particularly suited for use in neurosurgery (or related anatomical investigations) and the separation of brain tissue. The retractor (1) includes an inflatable body (2) with a torus shape. The torus shape provides the portions of the body which contact the brain tissue are edgeless. This seeks to minimise areas in the tissue where damaging pressure is applied. A valve (3) allows the retractor to be dynamically inflated/deflated during procedures, or alternatively, inflated to a desired pressure before use. The valve is disposed on the top face of the retractor in use, facing away from the brain tissue, so as not to contact any brain tissue or interfere with positioning of the retractor. In this example, a syringe (4) connected via a line (5) to the valve (3) permits dynamic injection/withdrawal of saline fluid from the body of the retractor. The retractor (1) is formed of a silicone material. However, it will be appreciated that the retractor may be formed of other suitable polymer materials.

[0036] It will be appreciated that the presently described retractor provides several advantages over conventional retractors. For example, it is unmounted and insertable, which limits injury/damage due to unintended movement of the patient. It may also have edgeless contact portions in seeking to reduce instances where damaging pressure is applied to the anatomical structure to be separated. It may also be dynamically inflated/deflated during procedures so as to allow real-time adjustment of functionality (e.g. conformability, separation distance). It will also be appreciated that in addition to allowing access for surgical instruments, the passage/corridor provided allows a surgeon to more clearly visualise deep structures, by means of microscopic, endoscopic, exoscopic or naked eye methods.

[0037] In some forms, the retractors as described herein may be configured to be linked together, so as to extend the passage length (i.e. provide a longer protected surgical access corridor) or increase separation width.

[0038] Optional embodiments of the present invention may also be said to broadly consist in the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0039] Although a preferred embodiment has been described in detail, it should be understood that various changes, substitutions, and alterations can be made by one of ordinary skill in the art without departing from the scope of the present invention.

[0040] It will be appreciated that various forms of the invention may be used individually or in combination.

Claims

The claims defining the invention are as follows:

1. An unmounted insertable retractor for separating anatomical structures during surgery, anatomical investigations or the like, the retractor having a body with a passage therethrough, the body configured to be placed between anatomical structures to be separated.

2. The retractor as claimed in claim 1, wherein the body includes opposite outward facing contact portions for contacting the anatomical structures to be separated.

3. The retractor as claimed in claim 2, wherein the contact portions are edgeless.

4. The retractor as claimed in claim 2 or 3, wherein the body is configured such that the separation distance as provided between opposing contact portions is greater than the passage length.

5. The retractor as claimed in any one of the preceding claims, wherein the passage extends along a substantially linear axis, between a passage inlet and a passage outlet.

6. The retractor as claimed in any one of claims 1 to 5, wherein the body is conformable to the anatomical structures to be separated.

7. The retractor as claimed in any one of claims 1 to 5, wherein the body is compressible yet resilient.

8. The retractor as claimed in any one of claims 1 to 5, wherein the body is substantially non-compressible.

9. The retractor as claimed in any one of claims 1 to 5, wherein the body is inflatable.

10. The retractor as claimed in claim 9, wherein the body is configured to be inflatable to a state where the body is conformable to the anatomical structures to be separated.

11. The retractor as claimed in claim 9, wherein the body is configured to be inflatable to a state where the body is compressible yet resilient.

12. The retractor as claimed in claim 9, wherein the body is configured to be inflatable to a state where the body is substantially not compressible.

13. The retractor as claimed in claim 9, wherein the body is inflatable to:

a first functional state, wherein the inflated body is conformable to the anatomical structures to be separated;

a second functional state, wherein the inflated body is compressible yet resilient; and

a third functional state, wherein the inflated body is substantially not compressible.

14. The retractor as claimed in any one of claims 9 to 13, wherein the retractor configured to allow dynamic inflation/deflation.

15. The retractor as claimed in claim 14, including a valve that permits dynamic inflation/deflation .

16. The retractor as claimed in any one of the preceding claims, wherein the shape of body is substantially toroidal.

17. The retractor as claimed in any one of the preceding claims, wherein the body is substantially torus shaped.

18. The retractor as claimed in any one of the preceding claims, wherein the entire outer surface of the body is substantially smooth.

19. The retractor as claimed in any one of the preceding claims, wherein the body is configured such that the dimensions of the passage are fixed.

20. The retractor as claimed in claim 19, wherein the body includes a rigid support portion around the passage so as to substantially maintain the dimensions of the passage.

21. The retractor as claimed in claim 19, wherein the retractor includes a rigid support structure around the passage so as to substantially maintain the dimensions of the passage.

22. The retractor as claimed in claim 21, wherein the rigid support structure is located within the body.

23. The retractor as claimed in any one of the preceding claims, wherein the body formed of a substantially transparent material.

24. The retractor as claimed in any one of the preceding claims, wherein the body is formed of a polymer material.

25. The retractor as claimed in any one of the preceding claims, wherein the body is formed of an elastomeric material.

26. The retractor as claimed in any one of the preceding claims, wherein the body is formed of silicone.

27. The retractor as claimed in any one of the preceding claims, configured for separating brain tissue.

28. A method of separating brain tissue during surgery, anatomical investigations or the like, including placing a retractor as claimed in any one of the preceding claims between brain tissue to be separated.