Technical Field

[001] The technology relates to minimally invasive surgical devices and methods for providing access to bones, particularly the spine.

Cross Reference to Related Application

[002] This application claims priority to Australian provisional patent application number 2022902134, filed 29 July 2022, the disclosure of which is incorporated herein by reference.

Background

[003] Surgical procedures invariably involve trauma to tissues around the surgical site. Smaller skin incision and decreased disruption of surrounding tissue during the surgical approach reduces postsurgical healing time, and pain. Thus, there is increasing demand for minimally invasive surgical (MIS) techniques to perform surgical procedures, through smaller incisions with less disruption of the surrounding soft tissues, with the goal of decreased recovery times, lessened morbidity, and cost savings.

[004] Minimally invasive surgical access to bones, including bones in the spine typically involves a tubular retractor to decrease the collateral damage to spinal muscles compared to a conventional open posterior approach. Muscle splitting serial tube dilators and retractors were designed to minimize disruption of the paraspinal musculature and provide direct and focal access to the diseased anatomy.

[005] A tubular retractor system has the advantage of viewing the surgical images directly under the microscope. Though the primary indication for which the tubular retractor system was developed is lumbar disc herniation but over time and with certain modifications, tubular retractors have been used to carry out multilevel interbody fusions using multiple ports and augmented by percutaneous screws and rods as well as minimally invasive anterior approaches. The use of tubular retractors preserves stability provided by the envelope of paraspinal muscles.

[006] However, tubular retractors can impinge on the spinous process or lamina thereby limiting the depth of insertion and consequently compromising visualisation due to muscle creep around the end of the retractor. In addition use of tubular retractors requires initial serial dilation before the tubular retractor is placed over the last dilator. With this approach the there is a risk that the dilators can migrate into the interlaminar space and cause an unintended durotomy or damage the spinal nerves or spinal cord. [007] Accordingly there is a need for improved minimally invasive approached to provide surgical access to the bones generally and bones of the spine in particular.

[008] The present inventor has developed a minimally invasive surgical device and method allowing for stable access to bones, with distal stabilization with an inflatable cuff, with the additional benefit of reducing muscle creep into the surgical corridor. The device provides access for one or more endoscopes and provides additional working space at the bone surface compared to existing methods and devices. The device can be incorporated into either a single, biportal or multiportal surgical techniques.

Summary

[009] In a first aspect, there is provided a device for accessing a bone of a subject, the device comprising a tubular member having a proximal end, a distal end and a lumen extending therebetween, wherein the proximal end of the tubular member comprises an inflation port in fluid communication with an inflatable cuff at or adjacent to the distal end, and wherein in use the inflatable cuff draws tissue away from the bone, and/or reduce muscle creep into the surgical corridor adjacent the distal end of the tubular member and the bone.

[010] The bone access device may further comprise: a) a hub having a proximal end and a distal end and a lumen extending therebetween; b) wherein the tubular member comprises a proximal end body connected to the distal end of the hub, a distal end and a lumen extending between the two ends, the tubular member comprises a collar adjacent the proximal end body and an inflatable cuff adjacent the distal end; and wherein the lumen of the tubular member is in communication with the lumen of the hub; and c) the proximal end of the hub is detachably connected to a cap, wherein, in use the inflatable cuff and the collar co-operate to draw tissue away from the bone and/or reduce muscle creep into the surgical corridor adjacent the distal end of the tubular member and the bone.

[011] In one embodiment the proximal end body further comprises an inflation port in fluid communication with an inflation lumen extending between the inflation port and the inflatable cuff. [012] In use the inflatable cuff may further provide a fluid pocket adjacent the bone, for example to allow an endoscope tip advanced through the tubular member to be positioned within the fluid pocket to facilitate efficient surgical workflow.

[013] In some embodiments the inflatable cuff provides pressure to a fluid in the fluid pocket.

[014] A luer fitting, a valve assembly, or both may be attached to the inflation port.

[015] The collar is moveable along the length of tubular member and may comprise a locking means.

[016] In some embodiments the outer surface of the tubular member is threaded and the inner surface of the collar has a complementary thread.

[017] In an embodiment the cuff is elastic and all or the major portion of the inner surface of the cuff in its deflated condition is closely adjacent to and may be in contact with the outer surface of the tubular member.

[018] The cuff may be pre-shaped to have a bulbous, or flat, or any form when inflated.

[019] The bone may be a spinal bone such as a vertebra, sacrum or coccyx. For example a spinous process, lamina, transverse process, facet or body of a vertebra.

[020] In a third aspect there is provided a method of providing bone access comprising a) advancing the device of the first aspect into an incision such that the distal end of the tubular member is adjacent to or abuts the bone; b) inflating the cuff to draw tissue away from the bone.

[021] In a fourth aspect there is provided a method of providing bone access comprising c) advancing the tip of a guidewire to be adjacent a bone of a subject; d) advancing the device of the second aspect over the guidewire until the distal end of the tubular member is adjacent to or abuts the bone; e) inflating the cuff; and moving the collar along the tubular member to clamp the subject's tissues between the collar and the inflated cuff such that the inflatable cuff and the collar co-operate to draw tissue away from the bone.

[022] Inflation of the cuff may further provide a fluid pocket adjacent the bone, for example to allow an endoscope tip advanced through the tubular member to be positioned within the fluid pocket to facilitate efficient surgical workflow. [023] In some embodiments the method further comprises providing a fluid to the fluid picket.

[024] In an embodiment inflation of the cuff provides pressure to a fluid in the fluid pocket.

[025] The method may further comprise removing the guidewire and removing the cap.

[026] In a preferred embodiment the bone is a spinal bone. The spinal bone may be a vertebra, sacrum or coccyx. For example a spinous process, lamina, transverse process, facet or body of a vertebra.

[027] In some embodiments the method may comprise using the distal end of the tubular member to bluntly dissect tissue to access the bone.

Definitions

[028] Throughout this specification, unless the context clearly requires otherwise, the word 'comprise', or variations such as 'comprises' or 'comprising', will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[029] Throughout this specification, the term 'consisting of' means consisting only of.

[030] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present technology. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present technology as it existed before the priority date of each claim of this specification.

[031] Unless the context requires otherwise or specifically stated to the contrary, integers, steps, or elements of the technology recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements.

[032] In the context of the present specification the terms 'a' and 'an' are used to refer to one or more than one (ie, at least one) of the grammatical object of the article. By way of example, reference to 'an element' means one element, or more than one element.

[033] In the context of the present specification the term 'about' means that reference to a figure or value is not to be taken as an absolute figure or value, but includes margins of variation above or below the figure or value in line with what a skilled person would understand according to the art, including within typical margins of error or instrument limitation. In other words, use of the term 'about' is understood to refer to a range or approximation that a person or skilled in the art would consider to be equivalent to a recited value in the context of achieving the same function or result.

[034] Those skilled in the art will appreciate that the technology described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the technology includes all such variations and modifications. For the avoidance of doubt, the technology also includes all of the steps, features, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps, features and compounds.

[035] In order that the present technology may be more clearly understood, preferred embodiments will be described with reference to the following drawings and examples.

Brief Description of the Drawings

[036] Figure 1 illustrates one embodiment of the device 10.

[037] Figure 2 illustrates the insertion of guidewire 100 into a subject.

[038] Figure 3 illustrates the device described herein being advanced over the guidewire 100.

[039] Figure 4 illustrates the distal end of the tubular member 50 adjacent to the spine and the removal of the guidewire 100.

[040] Figure 5 illustrates removal of the cap 30 once the device 10 is inserted into a subject.

[041] Figure 6 illustrates the distal end of the tubular member 50 abutting the spine and the collar 70 moved along the tubular member 50 to be in contact with the subject's skin.

[042] Figure 7 illustrates inflation of the cuff 60.

[043] Figure 8 illustrates that subject's tissues secured between the inflated cuff 70 and the collar 70 which is locked in place on the tubular member 50 thereby providing a clear surgical filed at the bone surface.

[044] Figure 9 illustrates a surgical instrument inserted through the lumens of the device and access the bone surface.

[045] Figure 10 illustrates another embodiment of the device 10.

Description of Embodiments

[046] The description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

[047] There is provided a device for prevertebral access. The device 10 comprises a hub 20, and a generally elongate tubular member 50 extending from one end of the hub 20. As shown in further detail in FIG. 1, the hub 20 includes a body 21 having a proximal end 22 and a distal end 23 and a central lumen extending therebetween. In one embodiment, a port 55 is provided in the side of the main body 21 of hub 20. The port 55 formed in the main body 21 of the hub 20 is in fluid communication with an inflatable cuff 60. The tubular member 50 has a central lumen extending between the proximal end 22 and the distal end 23 of the main body 21 of hub 20. The tubular member 50 has a port 25 in fluid communication with the central lumen. The port 25 may comprise a luer fitting or a valve assembly can be attached to the port 25 so that fluid can pass through the valve/luer and into the lumen 59 of the tubular member 50.

[048] In an exemplary embodiment the central lumen comprises a first lumen portion and a second lumen portion. The first lumen portion and the second lumen portion can have a common central axis. It will be appreciated by one skilled in the art that first lumen portion and second lumen portion are not required to have a common central axis. The first lumen portion is proximate to the distal end 23 of the hub 20 while the second lumen portion is proximate to the proximal end 22 of the hub 20.

[049] The device 10 comprises a cap 30 detachably connected the central lumen proximate to the proximal end 22 of the hub 20. As shown in FIGS. 1 and 3-5, the surface of cap 30 is sized and configured to be received within the proximal end 22 of the hub 20. In one embodiment illustrated in FIG. 1, the surface of the cap 30 forms a protrusion 32 to be received by the interior surface of the proximal end body 22 of the main body 21 of the hub 20, and the central lumen 59 of tubular member 50. The proximal end 22 of the main body 21 of the hub 20 is configured to receive the protrusion 32. It will be appreciated that the protrusion 32 of the cap 30 can have various other configurations and shapes as long as it is configured to cooperate with the proximal end 22 of the hub 20 and the central lumen 59 of tubular member 50. In one exemplary embodiment, proximal end 22 of the hub 20 and a portion the exterior surface 32 cooperate form a seal.

[050] In one embodiment the cap 30 has a lumen extending through the protrusion 32 to enable advancement of the device 10 over guidewire 100.

[051] The cap 30 has an opening 34 in a medial portion thereof that is sized to receive a guidewire 100. The opening 34 extends through protrusion 32. An exemplary embodiment of the cap 30 of the present invention is illustrated in FIGS 1 and 3-5. In one embodiment, the cap 30 is configured to cooperate the proximal end 22 of the hub 20. In particular, in this embodiment the exterior surface of the cap 30 configured to receive the proximal end 22 of the hub 20. Similarly, the proximal end 22 of the hub 20 has an opening formed therein configured to receive the cap 30. It will be appreciated by one skilled in the art that the distal portion of the cap 30 and the opening in the proximal end 22 of the hub 20 can have various other configurations and shapes as long as they are configured to cooperate and have a sealing engagement. Alternatively, by way of example and not limitation, that the distal portion of the cap 30 and the opening the proximal end 22 of the hub 20 could be U-shaped, round, rectangular square, oval, elliptical, tapered, or any combination thereof as long as they are configured to detachably cooperate.

[052] The port 55 is in fluid communication with an inflation lumen extending between the port 55 and an inflatable cuff 60 at or adjacent the distal end of the tubular member 50. The proximal end of the inflation lumen is connected in a fluid-tight connection with the inflation port 55. In one embodiment the inflation lumen 55 is formed within the wall of the tubular member 50 or may be formed by a tube or conduit connecting the inflation port 55 and cuff 60. The tube or conduit may be secured, such as by an adhesive, heat bonding or other suitable means, to the tube tubular member 50. The port 55 may comprise a luer fitting or a valve assembly can be attached to the port 55 so that fluid can pass through the valve/luer and into the inflation lumen extending between the port 55 and an inflatable cuff 60.

[053] In some embodiments the tubular member 50 comprises a grip 65. The grip 65 may be integrally formed with the tubular member 50 or may be fastened to tubular member 50. The grip 65 typically comprises a textured surface, for example a series or pattern of raised sections as illustrated in FIGS 1 and 3-8.

[054] The cuff 60 is preferably elastic and sits 'tight-to-shaft' as shown. That is when disposed on the tubular member 50, all or the major portion of the inner surface of the cuff in its deflated condition is closely adjacent to and may be in contact with the outer surface of the tubular member 50 . The cuff is preferably formed of an elastic material, such as natural or synthetic rubber, or a suitable elastomeric thermoplastic material. A latex or silicone rubber, for example, may be used. The cuff 60 is secured to the tubular member 50 adjacent the distal end, which end is adapted to be inserted into a subject. The cuff 60 is fixed in relation to the outer surface of tubular member 50, such as by an adhesive, solvent bonding, heat bonding or in any other suitable manner. The inflatable or expansible portion of cuff 60, is, of course, able to move away from tubular member 50 when the cuff is inflated, the cuff assuming a bulbous or toroidal form as indicated in FIGS. 7 and 8. [055] The cuff 60 may be pre-shaped if desired to have a bulbous form when inflated under slight inflation pressures. In this embodiment, the cuff may be made of a plastic which is not elastic or mildly elastic, such as urethane, polyvinyl chloride or the like. Because the elastomeric 'tight-to-shaft' cuff is capable of quickly and fully collapsing when deflated for easy removal of the tubular member 50 from the subject, it is preferred to the type which is preformed in the bulbous form and which generally becomes irregular in shape when deflated. Either type of cuff can be used.

[056] The cuff 60 may be located at the very distal end of the tubular member 50, or just distal to the collar 70, or at any position therebetween.

[057] The cuff 60 is depicted herein as a balloon, however various other embodiments can be used such as a deployable umbrella or cup, or other structural mechanism to keep the tubular member 50 in place.

[058] In some embodiments where the cuff 60 is an employable umbrella or cup the deployed shape of the umbrella or cup is substantially complimentary to the collar 70, such that when in use to draw tissue away from the bone cooperation between the cuff 60 and collar 70 is enhanced.

[059] In use, with the cuff 60 deflated, the tubular member 50 may be inserted into the subject, either by way of a previous surgical incision or as illustrated in FIGS 2-5 using a guide wire so that the cuff 60 is positioned internal to the subject's skin, subcutaneous fat and musculature. The cuff 60 can then be inflated, for example by using an air or saline filled syringe attached to the inflation port 55.

[060] As can be seen in FIGS, 7-10, when inflated the cuff 60 draws tissue away from the bone. In some embodiments inflation of the cuff 60 reduces muscle creep into a surgical corridor adjacent the distal end of the device and the bone.

[061] In some embodiments the inflatable cuff 60 provides a fluid pocket adjacent the bone. Creation of a fluid pocket allows endoscope tip, which may be advanced through the tubular member, to be positioned within the fluid pocket to facilitate efficient surgical workflow, that is the fluid pocket provides space for the surgeon to work and allows for clearance of any debris generated during surgery which can be removed when the fluid is removed or exchanged. Accordingly, in some embodiments a fluid such as sterile saline can be provided to the pocket through the device or separately, for example by injection.

[062] In embodiments where fluid is provided to the pocket the cuff 60, when inflated provides pressure to a fluid in the fluid pocket. [063] In some embodiments the device further comprises a collar 70 positioned adjacent the proximal end of the tubular member 50. The collar 70 is moveable along the length of tubular member 50 and comprises a locking means such the collar 70 can be fixed at a desired location on the tubular member 50. Any suitable locking means may be used such as a set screw, pin, or other device, that can be used to tighten the collar 70 onto the tubular member 50.

[064] In some embodiments the outer surface of the tubular member 50 is threaded and the inner surface of the collar 70 has a complementary thread such that the collar can be screwed along the axis of the tubular member 50.

[065] FIGS. 1 and 9 depict exemplary embodiments of the tubular member 50. In Figure 9, the tubular member 50 includes a proximal end body 52 and a distal end 57 with a lumen extending between the two ends. In some embodiments the distal end 57 of the tubular member 50 is adapted to dissect muscle from the bone using a back and forth scraping technique. This helps lift the muscle off the bone when inflating the cuff 60 and pulling it away from the bone. Accordingly, the distal end 57 may have a narrow tip to assist with initial placement over a guidewire, and initial dissection of tissue attached to the bone. The tubular member 50 is comprised of a durable material and is able to maintain the lumen 59 when in place and surrounded by the subject's tissue. As noted above the proximal end body 52 of the tubular member 50 is configured to be received proximate to the distal end 23 of the hub 20 for example by being screwed into the distal end 23 or by the use of a retaining means comprising angular ridges or teeth-like features formed in the distal end the retainer configured to contact and engage the proximal end body 52 of the tubular member 50. It will be appreciated by one skilled in the art that the retaining means may have various other configurations and perform the function thereof. In other embodiments proximal end body 52 of the tubular member 50 is resiliently engaged in the lumen of the hub 20 by a snap-fit or frictional engagement, various other methods of attachment could be utilized, such as welding, adhesives, mechanical fasteners and the like.

[066] It will be appreciated that the proximal end body 52 of the tubular member 50 may have various other configurations. The proximal end body 52 may be generally shaped as depicted in FIGS. 1 and 2-9.

[067] It will be appreciated that, although it is not illustrated, the distal end 57 of the tubular member 50 can include a tapered portion depicted in FIG. 9A in which the diameter of the tubular member 50 is gradually reduced. Such a tapered portion may be produced through known manufacturing methods such as drawing, sanding, grinding, heat forming or other similar processes.

[068] The device or components thereof can be formed using one or more materials known in the art as suitable sterile medical grade biomaterials, synthetic materials or plastics for single, or multiple use. Exemplary materials may include, but are not limited to, flexible PVC, polyurethane, silicone, liner low-density polyethylene (“LLDPE”), polyethylene, high density polyethylene, (“DHPE”), polyethylene-lined ethylvinyl acetate (“PE-EVA”), polypropylene, latex, thermoplastic rubber, polytetrafluoroethylene (PTFE), expandable polytetrafluoroethylene (ePTFE), fluoroethylene-propylene (FEP), perfluoroalkoxy (PFA), ethylene-tetrafluoroethylene-copolymer (ETFE), ethylene-chlorotrifluoroethylene (ECTFE), polychloro-trifluoroethylene (PCTFE), polyimide (PI), polyetherimide (PEI), polyetherketone (PEEK), polyamide-imide (PAI), other fluoropolymers, and the like.

[069] Exemplary materials used in the device or the components thereof may also include elastomers or thermoplastic elastomers. Examples of elastomers include, but are not limited to, natural rubber, silicone rubber, polyurethane rubber, polybutadiene, polyisoprene, chlorosulfonated polyethylene, polysulfide rubber, epichlorohydrin rubber, ethylene propylene rubber, and the like or any combination thereof. These materials provide the elasticity that enable the sheath to expand and/or contract to accommodate the removal/insertion of a medical device as required. Other materials that can be used can include, but are not limited to, dip coated type silicones.

[070] In other embodiments, the materials suitable for use in an introducer sheath and the components thereof are configured to have chemical resistance, crack resistance, no toxicity, Food and Drug Administration (“FDA”) or other regulatory compliance, non- electrically conductive, dimensional stability, and/or be sterilized by ethylene oxide, gamma radiation, autoclave, UV light, ozone, and the like.

[071] In addition, the selection of materials for the device or its components can depend on a variety of factors that include, but are not limited to, a particular stiffness and/or flexibility of the device or any portion thereof, including the desired stiffness and strength to enable insertion of the tubular member, the ability to resist kinking, and the like.

[072] In one embodiment, one or more of the hub 20, the tubular member 50, the cap 30, and the proximal end body 52 may be constructed of materials such as acrylonitrile butadiene styrene (ABS), polyvinylchloride (PVC), polycarbonate. In one embodiment, the hub 20, the cap, and the proximal end body 52 are formed through injection molding. [073] The elongate tubular member 50 may be constructed of polytetrafluoroethylene, Teflon, or similar materials. In one embodiment the tubular member 50 is fabricated by and may be constructed of a single material or may from more than one material.

[074] It will be understood by persons skilled in the art, that various other materials can be used for individual components. For example, any of the above identified materials may further include glass reinforcement particles mixed therewith.

Methods

[075] The devices described herein can be used to effect percutaneous bone access, particularly to the spine. In one embodiment a surgeon will initially identify the insertion point in a suitably anesthetized subject, either by using an anatomical landmark or with the aid of ultrasound or other imaging technique.

[076] A guide wire is then inserted into the subject and the proximal end of the guidewire advanced using a translation motion with until the tip of the guidewire is adjacent to or abuts the bone (FIGS 2-4). Alternative methods for placement of guidewires are known in the art and include the use of a needle or catheter.

[077] Once the guidewire has been advanced into position the distal end of the tubular member 50 is advanced over the guidewire and the guidewire is fed through the opening 34 in cap 30 and protrusion 32. The device is advanced over the guidewire 100 (FIGS 2-3) until the distal end of the tubular member 50 is adjacent to or abuts the bone (FIG 4). The guidewire and cap are then removed (FIG 4 and 5) and the cuff 60 inflated (FIG 7). Cuff inflation (FIG 7) prevents the device being withdrawn from the subject. In embodiments where the device includes a collar, the collar 70 is then advanced distally along the tubular member 50 to clamp the device in place by as illustrated in FIG 8 thereby providing surgical access to the bone as illustrated in FIG 9.

[078] In some embodiments and with reference to FIG 9, the device can be inserted into an incision and advanced towards the bone. The device can optionally be used to bluntly dissect tissue as it is advanced. Once the device is advanced to the desired position the cuff 60 is inflated and prevents the device being withdrawn from the subject and to withdraw the tissue from the adjacent bone, and/or reducing muscle creep into the surgical corridor at the distal end of the tubular access device.

[079] In some embodiments one or more dilators is used to increase the size of the incisions before introducing the device into the incision and advancing it towards the bone. [080] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.