WO2015052336A2

WO2015052336A2 - Bone spreader/compressor

Info

Publication number: WO2015052336A2
Application number: PCT/EP2014/071813
Authority: WO
Inventors: John O'byrne
Original assignee: The Royal College Of Surgeons In Ireland
Priority date: 2013-10-11
Filing date: 2014-10-10
Publication date: 2015-04-16
Also published as: WO2015052336A3; GB2519288A; GB201318081D0

Abstract

A handheld surgical device 1 comprising a pair of moveable opposing arms 4 a platform 17 releasably attachable to each arm 4, wherein each platform 17 comprises a bone-engaging surface 19 moveable relative to the arm 4.

Description

Title

Bone Spreader/Compressor

Field of the Invention

[0001] This invention is directed to the field of medical instruments. In particular, the invention is directed to instruments for spreading or compressing bones and attachments for instruments for spreading or compressing bones.

Background to the Invention

[0002] A bone spreader is a handheld device which fits in between two opposing segments of bone in a human or animal body and separates them. The spreader maintains separation between the segments until it is removed. Common prior art bone spreaders have rigid tips which often contact the bone along edges or corners of the spreader. This can cause damage to the bone and the surrounding areas. A spreader device which reduced the incidence of damage in the areas surrounding the site of use would be an improvement on the state of the art. Similar shortfallings are experienced with existing compressors which are similar handheld devices, but designed to hold/compress a portion of bone between opposing arms of the device.

Summary of the Invention

[0003] The present invention provides a handheld surgical device comprising a pair of moveable opposing arms, a platform releasably attachable to each arm, wherein each platform comprises a bone- engaging surface moveable relative to the arm.

[0004] The moveability of the bone-engaging surface relative to the arm is advantageous in that it prevents concentration of contact pressure into a point or line of loading on the surface to be contacted by the arms, in use. This is particularly advantageous when the arms are brought into contact with a bone surface within a human or an animal during surgery. Such concentrated pressures may cause damage to the bone, especially to abnormally weak bone. The moveability of the bone-engaging surface maximises the contact area between the platform and the bone, which may not lie in a common place with the arm. As such, the arm need not be exactly parallel to the bone surface at the contact point.

[0005] The platform may be releasably attachable to an inner surface of an arm. This allows the platforms to apply pressure to opposite surfaces of a bone placed between the platforms on each arm, thus holding the bone steady. A bone compressor would take this form.

[0006] The platform may be releasably attachable to an outer surface of an arm. This allows the platforms to apply pressure to surfaces in order to hold the surfaces apart. A bone spreader would take this form. [0007] The platform may be releasably attachable to a sleeve into which the arm is receivable.

[0008] The sleeve may form part of a capping piece for capping a tip portion of the arm.

[0009] The platform may be substantially circular in cross section. This is advantageous, as a circular platform is devoid of corners which can act as focal points for pressure applied to the platform. The circular shape may also be advantageous for certain surgery types.

[0010] The platform may be substantially rectangular in cross section with rounded edges. This is advantageous as the rounded edges mean that the platform will not have sharp corners which can act as focal points for pressure applied to the platform. The rectangular shape may also be advantageous for certain surgery types.

[0011] The bone engaging surface of the platform may comprise a convex surface. This is

advantageous as it allows for a closer fit between the convex surface of the platform and a concave surface to which the platform is applied, for example a concave surface on a bone.

[0012] The bone engaging surface may be conformable to the shape of the surface to be engaged. This is advantageous as it further provides for even spreading of pressure across the surface to which it is being applied, for example a bone surface.

[0013] The platform may be pivotable with respect to the arm to which it is releasably attached. The platform may be pivotable by means of a ball and socket joint and the platform may be connected to a ball element. This provides for a range of motion for the platform meaning that its position can be adjusted to provide compression or spreading action in a wide variety of angled configurations.

[0014] The ball element may be receivable into a socket on each arm. The ball shaped element may be receivable into a socket within the sleeve. The ball element and the socket may comprise polished surfaces to reduce friction between the ball and the socket. This provides for very smooth movement of the ball within the socket and thus very smooth movement of the platform connected to the ball.

[0015] The ball and the socket may comprise roughened surfaces to increase friction between the ball and the socket. This facilitates releasable locking of the ball into a position by means of a friction grip between the ball and the socket.

[0016] The device may further comprise means for restricting the degree of rotation of each ball within each socket. This is advantageous as different degrees of motion may be required for different surgery types. [0017] The device may further comprise a locking means for locking the capping piece to the arm, wherein the locking means are provided on the inner surface of a tip receiving recess within the capping means. This provides a means of securely fastening the capping piece to the arm of the device.

[0018] The capping piece and its respective arm may comprise complementary male and female engagement means. This provides a straightforward means of connecting a capping piece to an arm of the device.

[0019] The present invention further provides a capping piece for a handheld surgical device, the capping piece comprising means for attachment to an arm of the surgical device; a platform comprising a bone-engaging surface; the bone engaging surface being moveable relative to the capping piece. This is advantageous as the capping piece is attachable to a variety of devices and may be counter-fit onto existing spreader/compressor devices. Furthermore, the platform prevents damage to surrounding areas.

Brief Description of the Drawings

[0020] The present invention will now be described with reference to the accompanying drawings, in which Figure 1 shows a surgical device in accordance with one embodiment of the invention. Figure 2 shows a surgical device in accordance with a further embodiment of the invention. Figure 3 shows a contact platform for use in the embodiment of figure 1 or figure 2. Figures 4A and 4B show the contact platform of figure 3 in use. Figure 5A shows one embodiment of contact platform suitable for use in the device of figure 1 or figure 2. Figure 5B shows a further embodiment of contact platform suitable for use in the device of figure 1 or figure 2. Figure 6 shows a rounded edge of one embodiment of platform suitable for use in the device of figure 1 or figure 2. Figure 7 shows an alternative embodiment of contact platform suitable for use with device of figures 1 or figure 2. Figure 8 shows an alternative embodiment of contact platform suitable for use with the device of figure 1 or figure 2. Figures 9A to 9C show different embodiments of platform ball joint suitable for use with the device of figure 1 or figure 2. Figure 10 shows the ball joint of figure 9A received into a socket. Figure 10A shows cross section of tip and contact platform in accordance with one embodiment of the invention. Figure 10B shows a tip and contact platform in accordance with an alternative embodiment of the invention. Figure 1 1 shows an alternative embodiment of device in accordance with the present invention. Figures 12 and 13 show embodiments of handles suitable for incorporation in the device of the invention. Figure 14 shows a ratchet bar mechanism suitable for incorporation in the device of the invention. Figure 15 shows a threaded bolt mechanism suitable for use in the device of the invention.

Detailed Description

[0021] Figure 1 shows a handheld surgical device 1 according to the present invention. The device may be held by a pair of handles 2 which pivot about a pivot point 3. Each handle comprises a raised area 31 . When gripped by a hand, the raised areas 31 prevent the hand from slipping down the device. Each handle is further connected to a pair of arm elements 4. The arm elements each comprise a tip area 5. A contact platform 17 is releasably attached to each of the arm elements 4 towards the tip area 5. The platform further comprises a bone engaging surface 19 which is moveable relative to the arm element 4 to which it is attached. Separation of the handles 2 from each other will cause the arms 4 to be drawn together. This allows the tip areas 5 comprising the platforms 17 to be inserted into an opening, for example an incision in a human or animal body. Compression of the handles 2 will cause the arms 4 to be moved apart such that pressure may be applied by the engaging surfaces 19 onto surfaces surrounding the platforms 17. In this manner, an opening or a separation of surfaces onto which engaging surfaces 19 are pressed may be maintained so long as the handles are compressed.

[0022] Figure 2 shows an embodiment of the device where a contact platform is fitted to the inner surface of the arm elements. This embodiment of device 1 may be used to compress opposite surfaces of a bone. The bone engaging surfaces 19 can be moved into position while the arms are in an open configuration. Separation of the handles will then draw the arms 4 closer together, thus compressing a bone located between the bone engaging surfaces 19.

[0023] Figure 3 shows a contact platform 17 suitable for use in either embodiment of device. As shown in figures 1 and 2, a contact platform 17 is fitted onto the tip of each arm of the device. The contact platform 17 is designed to engage a bone surface 18 or joint interior in a human body when the device is placed inside of the body. In practice, a surgeon positions the device manually so that each contact platform is placed on a bone surface 18 in the surgical area of interest. When the spreader embodiment is used, two bone surfaces are situated opposite one another and the instrument's contact platforms are positioned between them when the compressor embodiment is used, the instrument's contact platforms sit either side of a bone positioned between the arms. Manoeuvring the handles in the manner described above allows the contact platforms 17 to apply pressure to the bone surfaces such that they are separated or compressed as required.

In some embodiments, the tip to which the contact platform is fitted is an integral part of the arm, for example the end section of the arm. In other embodiments, the tip may be a separate piece, connected in some manner to the end of the arm.

[0024] Figures 4A and 4B demonstrate a contact platform in use. The platform comprises a surface 19 for engaging with a bone surface and a stem 20 for connecting the platform to a tip of an arm of the device. In this embodiment, the platform is releasably attachable to a tip in the form of a sleeve piece into which the end of the arm is receivable. The manner in which the contact platform 17 may be connected to the arm device 1 will be described in further detail below. Firstly, the contact platform itself is described.

[0025] The contact platform 17 may be rendered in a variety of different shapes in order to be suitable for use in different areas of human anatomy. During a typical surgical procedure, space is at a premium and blocking of the surgical field of vision is to be avoided. Circular and rectilinear shapes are particularly advantageous. [0026] Circularly shaped contact platforms 17 as shown in Figure 5A are advantageous, in the first instance because they do not possess corners. Corners can act as pressure points in a device, causing pressure from a force applied to the device to be focussed upon the corners and increasing the risk of damage to the areas which are in contact with the corners. A circular shape thus eliminates such pressure points and is subsequently less traumatic to surrounding areas. A circularly shaped contact platform is particularly advantageous in surgical situations such as osteotomies and arthroplasties.

[0027] Different surgical procedures may derive greater benefit from different shapes of contact platforms. For example, in the case of surgeries done in the lumbar spinal intervertebral space, a different shape of contact platform would be more advantageous. As approached from the front, the intervertebral space is narrow, 3-4cm wide, and it is not desirable that a bone-spreader should block much of this space. So, a rectilinear shape of contact platform would be suitable as shown in Figure 5B. The bone spreader, during a surgical procedure, is placed into the intervertebral space and then opened up thus spreading the superior and inferior vertebrae further apart. It is preferentially placed at the side of the intervertebral space, so surgical work can take place in the middle regions of the space. Once placed in this side area, each contact platform would engage the bone above and below.

[0028] As well as the shape of the platform being important to the usability of the device, it is further that the width of the platform is not so thin that it risks cutting through or subsiding into the bone.

[0029] A circular platform may also be useable in spinal interspaces. In this case, the diameter of the circular platform would have to be the same as the width of the rectilinear platform so that no blocking of the surgical field of vision takes place.

[0030] Whatever shape the contact platform is, it is desirable that it should have rounded edges 21 , as opposed to sharp or right angled, edges as demonstrated in Figure 6. As above, this eliminates pressure points and is subsequently less traumatic to surrounding areas.

[0031] It may be further advantageous for the contact platform to have a degree of pliability. For example, in a situation where the contact platform is placed on a bone surface with an inherent concavity, it is advantageous for the platform to bend to conform to and "fit into" the curvature of the bone surface as shown in Figure 7.

[0032] An example of such a curved bone surface within the body are the endplates of a lumbar vertebrae. However, this curvature is not of a regularized nature. For example, osteoporotic vertebrae may become far more concave than normal vertebrae. Furthermore, there may be smaller sub-zones of concavity within an overall flat surfaces endplate. Because a spreader device is intended to sit at the sides of an interspace, it would preferably rest on the "cortical rim" also known as the "apophyseal rim". This rim area consists of a more condensed, harder bone than the central regions. It may be substantially flat even when the central region is concave. In a preferred embodiment, the contact platform can conform to concavities with greater than a 98.8mm-circle-radius.

[0033] In one embodiment of the device, a contact platform is provided with a prefabricated curvature 22 as shown in Figure 8. In a further embodiment, the contact platform may be pliable such that it can safely bend within certain limits.

[0034] Figures 10 A, 10B show one embodiment of a contact platform 17 provided with a series of ridges or protrusions 32 on the platform surface. The protrusions may be pyramidal in shape with a flattened top surface. The purpose of the protrusions is to provide a better gripping contact with a bone surface.

[0035] This contact platform 17 may fabricated from any of the "surgical" stainless steels in common use, for example grades 304 and 316. The contact platform 17 may alternatively be made from titanium.

[0036] In a preferred embodiment, the contact platform is fabricated from a shape memory alloy, for example Nitinol®. A shape memory alloys contact platform may be placed onto a concave bone surface and then bend to conform to this concavity once pressure is applied on the platform by the surgeon opening or closing the handles of the device to spread body surfaces apart or compress body surfaces together as required.

[0037] In a further embodiment, the contact platform 17 is fabricated from a thin spring steel or other low modulus metal. This allows the platform bend under pressure to conform to a gentle curve. The contact platform may also be fabricated from a polymer, for example it may be fabricated from Nylon or

Polyethylene or Peek. The polymer could be stiff and non bending or pliant enough to bend and conform to concave surfaces, depending on the desired application of the platform.

[0038] The platform 17 is removable from the arm 4 of the device and is therefore replaceable. In typical use, a surgeon using the device will mount a sterile platform 17 on the arm 4 of the device. When a surgical procedure is concluded, the platform 17 may be removed for re-sterilisation or replacement. The removability of the platform may be provided by a ball and socket connection to the arm, however other means of connection providing the ability to remove the platform may be provided. One advantage of the ball and socket connections is the ability for the platform to swivel/pivot with respect to the arm of the device. A further advantage is that the connection is secure unless considerable force is used to separate the platform from the arm of the device. This ensures the platform does not become unintentionally disconnected during normal use.

[0039] In the embodiments of figures 9A and 9B, a stem links the platform to a ball 26. In the embodiment of figure 9A, the platform is maintained a smaller distance from the ball. In the embodiment of figure 9C the contact platform and ball are in direct contact. The two parts may be fabricated as one part. The stem increases the distance between the platform and the arm. [0040] Figure 10 shows the ball within a socket 27. This ball 26 and socket 27 joint provides for swivelling movement of the contact platform relative to the surface in which the socket is provided. Using force, the ball, and hence the platform may be pulled from the socket if the platform is to be replaced for example. The socket 27 is located on the arm 4 of the device. In an alternative embodiment (Figure 10A), the socket 27 is located on the underside of the platform and the ball 26 is located on the arm 4. In this embodiment, using force, the platform comprising the socket, may be pulled from the ball (Figure 10B) if the platform is to be replaced.

[0041] The level of friction at the interface of the ball surface 29 and the surrounding walls 30 of its sleeve piece will affect the movement of the platform. In one embodiment of the invention, the level of friction at this interface is as low as possible. This can be achieved, for example, with polished surfaces of ball and sleeve piece walls 30. In another embodiment, the surfaces are roughened to increase the level of friction between the surfaces. This has the effect of causing the surfaces to grip. This facilitates releasable locking of the ball into one position. In further embodiments, the profile of the socket may be adapted so as to limit the movement of the platform relative to the arm. For example, one or more protrusions may be provided on the area surrounding the socket opening to limit the movement of the ball within the socket when the underside of the platform contacts the protrusion(s). The protrusion(s) may take the form of a raised collar surrounding the socket opening. In alternate embodiments of the invention, the area surrounding the opening of the socket may be adapted to increase the maximum angle of rotation of the platform. For example, the surface surrounding the opening of the socket may be concave or may slope downward so as to accommodate the platform when tilted.

[0042] Further embodiments of the device 1 of the invention comprising variations on the handle are shown in Figures 1 1 to 15. The device 1 may further comprise a ratchet bar 6 or other means of maintaining the handles 2 in a compressed state such that the hands of the operator of the device are freed to perform additional tasks. The scissors like configuration of Figure 1 may also be embodied in a double-action scissors-like form as shown in figure 1 1. In this form, less space is required for the arms 4 to move further apart. In the simple scissors configuration, the handles and the arms are at opposite ends of two lever arms which are pivotally coupled together at one point. In the double-action scissors configuration, there are two points 7, 8 of pivoting between the handles and the arms.

[0043] Figures 12 and 13 show further embodiments of handles suitable for incorporation in the device of the invention. The handles 2 facilitate gripping by the surgeon's hand. The handles 2 may comprise grip-enhancing contouring 9 on their outer surfaces. The contouring 9 may take the form of a series of ellipsoidal concavities 10 spaced at intervals along the outer surface.

[0044] In one embodiment of the device, the handles 2 may have a very gentle inherent curvature along their length allowing for comfortable gripping in the hand. In an alternative embodiment, the handles may be straight. It is important that the handles are lightweight i.e., the handles must not be so thick or large that they too much weight to the overall device. [0045] In one embodiment, the tips 5, arms 4 and handles 2 may all lie in the same plane (the saggital or median plane). In a further embodiment, to aid visualisation of the surgical field, the handles 2 portion may be angled laterally away from this plane. This angulation is created by the introduction of smoothly curved portions, without sharp edges, somewhere between the tips 5 and the handles 2. In one embodiment, the curved-portion 1 1 which serves to offset tips from the handles may be situated just proximal to the tip areas as shown in Figure 12.

[0046] In a further embodiment, the curved portion 1 1 may be placed just after the pivot point 3 where the handles are pivotally connected together as shown in Figure 13. Preferably, either of these bends may be between zero and thirty degrees, most preferably between ten to fifteen degrees.

[0047] In a preferred embodiment, the arms 4 will be about one third of the length of the handles 2, so that about one third of the full length of the instrument is comprised of the arm elements and the two thirds is comprised of the handle elements. The division between the arm and the handles is at the pivoting joint between the two elements thus creating two symmetrical halves.

[0048] A biasing element such as a pair of leaf springs maintains the handles in a spaced apart configuration so that the arms and tips lie close together. This is the at rest state of the instrument required for the insertion of its tips into an anatomical space.

[0049] As set out above, the handles 2 may be attached to a ratchet bar 6 or other a locking mechanism, through use of which they can be maintained at a set distance relative to one another, thereby maintaining the arms 4 at a set distance apart also, thus maintaining separation of the distracted bone surfaces.

[0050] Two types of locking mechanisms for maintaining the arms of the instrument apart are considered suitable for use with the device. These are the ratchet bar 6 as shown in figure 14 and the threaded bolt 12 as shown in Figure 15.

[0051] In the ratchet bar 6 mechanism, a straight bar 13 bearing closely spaced ratchet teeth 14 extends between one handle 2 and the other. One of the handles 2 is also coupled pivotally to the bar. The distal tip of the non-coupled handle rests in the interspace between two adjacent teeth. In the "resting state" of the instrument it will lie between the two outermost teeth on the ratchet bar, with the handles as far apart as possible. The manual action of squeezing the handles 2 together acts to move the non-coupled handle's tip from between the two outermost teeth, bringing it closer toward the other handle, moving past intervening inter-teeth spaces until it comes to rest, once manual squeezing pressure has been released, in an inter-tooth space nearer to the coupled handle. The presence of the handle tip 15 between the teeth maintains the handle in that position until further pressure is applied.

[0052] In the threaded bolt 12 mechanism, a threaded bolt is coupled (again, pivotally) to one handle and slidably passes through the other handle. A locking nut 16 is threadably mounted on the outside end of bolt (i.e., the portion not between the handles). Movement of the nut, as a result of rotation along the bolt, acts to shorten the length of the bolt between handles and prevents the handles from moving apart. Movement of the nut is performed by the surgeon.

[0053] When used in a compressor device, movement of the handles of either figure 14 or 15 together causes movement of the arms together. When used in a spreader function movement of the handles together caused movement of the arms apart.

[0054] The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0055] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment.

Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Claims

A handheld surgical device comprising:

a pair of moveable opposing arms;

a platform releasably attachable to each arm, wherein each platform comprises a bone-engaging surface moveable relative to the arm.

The device of claim 1 wherein each platform is releasably attachable to an inner surface of an arm.

The device of claim 1 wherein each platform is releasably attachable to an outer surface of an arm.

The device of claim 1 wherein each platform is releasably attachable to a sleeve into which the arm is receivable.

The device of claim 4 wherein the sleeve forms part of a capping piece for capping a tip portion of the arm.

The device of any preceding claim wherein each platform is substantially circular in cross section.

The device of any of claims 1 to 5 wherein each platform is substantially rectangular in cross section with rounded edges.

The device of any preceding claim wherein the bone engaging surface of each platform is convex.

The device of any of any preceding claim wherein the bone engaging surface of each platform is conformable to the shape of a surface to be engaged.

The device of any preceding claim wherein each platform is pivotable with respect to the arm to which it is releasably attachable.

The device of any claim 10 wherein each platform is pivotable by means of a ball and socket joint.

The device of claim 1 1 wherein a ball element of the ball and socket joint is provided on each platform.

13. The device of claim 12 wherein the ball element is receivable into a socket on each arm.

14. The device of claim 12 wherein the ball element is receivable into a socket within the sleeve.

15. The device of any of claims 12 to 14 wherein the ball element and the socket comprise polished surfaces to reduce friction between the ball and the socket.

16. The device of any of claims 12 to 14 wherein the ball element and the socket comprise

roughened surfaces to increase friction between the ball and the socket.

17. The device of any of claims 1 1 to 16 further comprising means for restricting the degree of rotation of each ball within each socket.

18. The device of claim 5 further comprising a locking means for locking said capping piece to said arm, wherein the locking means are provided on the inner surface of a tip receiving recess within the capping piece.

19. The device of claim 5 or 18 wherein each capping piece and its respective arm comprise

complementary male and female engagement means.

20. A capping piece for a handheld surgical device, the capping piece comprising:

means for attachment to an arm of the surgical device;

a platform comprising a bone-engaging surface; the bone engaging surface being moveable relative to the capping piece.