Internal fixation device and associated methods

Abstract

A self-fastening plate device is described. The device includes a composite body formed in part from one or more pieces of shape-memory material. The body includes a longitudinal spine with lengths that could be selected by the surgeon extending from end to end. Wings straightened from preformed circular shapes may be integrated along the length of the spine in a transverse manner. These circularly bent wings are straightened partially or in full to a more flat / open configuration and returns back to a circular configuration when a temperature of the device is raised above a transition temperature of the shape-memory material, thereby generating a gripping force against the fractured bones to a reduced position.

Description

Internal Fixation Device and Associated MethodsTECHNICAL FIELDBACKGROUND

[0002] The goal in the treatment of bone fractures is the reduction of the fracture, realignment of the fractured fragments, and / or the preservation of the reduction through immobilization. In some of the cases of bone fracture, the surgeon will recommend surgery to ensure that the fracture is reduced, aligned accurately and fixed internally with fixation. Fixation with plates and screws is a common method. There has always been difficulty in maintaining reduction with clamps and K-wires (small fixation pins) while simultaneously adding a plate with screws for fixation. The traditional plate and screw fixation used in long bone fractures is often placed in a single only secures the bone in one plane, limiting the mechanical constraint and is biomechanically suspect to failure. Surgeons often add two plates in different planes and screws at various oblique angles to make up for this biomechanical weakness for additional constraint at the fracture site.

[0003] Orthopedic plates are typically used to fix long bone fractures and have been around since 1886. Plates can be purposed for one or more roles, including: hold together fractures; distribution of load; alignment; tension; and compression. Plates can have different lengths, shapes, sizes and screw holes depending on the fractured bone being fixed. Plates have been made of different metals including stainless steel and titanium as the most common.

[0004] Orthopedic screws, like common screws are used in the repair of fractured bone and / or to restore stability in a weak section. These screws may remain permanently or are removed in some cases. The screws are typically made of the same metal as the plate as to not create a battery effect (creation of electrical current from two dissimilar metals). Screws may have different lengths and widths depending on the plate and fracture being fixed. Some screws lock to the plate for more rigid fixation. Some screws do not lock to the plate but pull the plate to the bone in a compressive fashion. Most modern plates and screws are used in a combination of locking and compression screws.

[0005] Wing Clamp Fixation - Surgical clamps are routinely used in fracture management to help with reduction and temporary fixation. These clamps have handles like thecommon pair of pliers and are bulky and get in the way of adding plate fixation to the fractured bone.

[0006] There are a variety of bone clamps of various shapes and sizes with many different ends including sharp tenaculum shaped claws, lobster claws as example. These are temporarily used to hold a fracture in a reduced position until more permanent fixation (i.e., plate and screws) are added.SUMMARY

[0007] In accordance with the present disclosure, there is provided an internal fixation device comprising: an elongate spine member; and one or more elongate wings (or ribs) connected to (e.g., engaged with) the spine member in a transverse orientation; wherein the elongate wings comprise shape-memory alloy, such that: when the elongate wings are below a transition temperature, the wings are bendable to be in an open configuration in which the wings extend laterally away from the elongate spine member such that an interior surface of the spine member can be positioned adjacent to a bone; and when the elongate wings are heated to a transition temperature, the wings are biased towards a closed configuration in which the elongate wings are bent inwardly towards the interior surface so as to grip the bone.

[0008] It will be appreciated that, upon reaching (e.g., by heating to) the transition temperature, the distal end of each wing (i.e. the end furthest from the proximal end which is attached to the spine), may curve inwardly bringing the distal end inwardly towards the interior surface of the spine member. Positioning a bone next to the interior surface will allow the wings to grip the bone.

[0009] In position, the interior surface of the spine member may be in contact with the bone.

[0010] The elongate spine member may have a greater rigidity than the wings below the transition temperature. The elongate spine member may have a greater rigidity than the wings above the transition temperature.

[0011] The internal fixation device may comprise one or more pairs of elongate wings, each pair of elongate wings comprising two wings extending in opposite directions laterally from the same position on the elongate spine member. A pair of elongate wings may be formed from a unitary component (e.g., a single piece of shape-memory alloy material).

[0012] The spine member may comprise intermittent notches at both sides of the edges along the length to facilitate bending.

[0013] The spine member may comprise intermittent holes along the length to allow for screw fastening. The intermittent holes may be positioned on the longitudinal centerline.

[0014] The spine member may comprise intermittent magnets and / or slots on an interior side along the length to permit attachment to the wings.

[0015] The spine member may be formed from metal (e.g., metal alloy). The spine member may comprise titanium or its alloy.

[0016] The wing may comprise nickel titanium alloy.

[0017] The wing may comprise nitinol. Nitinol is a metal alloy of nickel and titanium.

[0018] A surface (e.g., the interior surface of the spine and / or an interior gripping surface of the wings) of the internal fixation device may comprise an antimicrobial surface texturing.

[0019] A surface (e.g., the interior surface of the spine and / or an interior gripping surface of the wings) of the internal fixation device may comprise an osseointegration promoting surface.

[0020] According to a further aspect, there is provided a method of manufacturing the internal fixation device described herein, wherein the method comprises: providing the elongate spine member; and connecting the one or more elongate wings to the spine member in a transverse orientation.

[0021] The method may comprise setting the closed configuration of the one or more wings.

[0022] Setting the closed configuration may involve a heat treatment. The heat treatment parameters chosen to set both the shape and the properties of the part are important, and usually need to be determined experimentally for each desired part's requirements. In general, a high-temperature period of at least 400 °C and times of at least 1-2 minutes is used to set the shape of the closed configuration. In other scenarios, temperatures of atleast 500 °C and times over 5 minutes are used. In other scenarios, temperatures of at most 1000 °C and times of less than 10 minutes are used. After the high-temperature period, rapid cooling or quenching is used to complete the heat treatment.

[0023] In accordance with an aspect of the present disclosure, there is provided a selffastening plate device which includes a composite body formed in part from one or more pieces of shape-memory material. The body includes a longitudinal spine with lengths that could be selected by the surgeon extending from end to end. Wings straightened from preformed circular shapes may be integrated along the length of the spine in a transverse (e.g., perpendicular) manner. These circularly bent wings are straightened partially or in full to a more flat / open configuration and returns back to a circular configuration when a temperature of the device is raised above a transition temperature of the shape-memory material, thereby generating a gripping force against the fractured bones to a reduced position.

[0024] In accordance with a further aspect the present disclosure, there is provided a kit comprising: an elongate spine member; one or more elongate wings connectable to the spine member in a transverse orientation; wherein the one or more elongate wings comprise shape-memory alloy, such that: when the one or more elongate wings are below a transition temperature while connected to the spine member in a transverse orientation, the wings are bendable to be in an open configuration in which the wings extend laterally away from the elongate spine member such that an interior surface of the spine member can be positioned adjacent to a bone; and when the one or more elongate wings are heated above a transition temperature while connected to the spine member in a transverse orientation, the wings are biased towards a closed configuration in which the elongate wings are bent inwardly towards the interior surface so as to grip the bone.

[0025] In accordance with a further aspect the present disclosure, there is provided surgical internal fixation device comprising: a longitudinal spine or plate with lengths that could be selected by the surgeon extending from end to end, comprising:wings integrated to along the length of the spine in a transverse, perpendicular or oblique manner and made of shape-memory material, wings straightened from preformed circular shapes which return to its circular configuration when a temperature of the device is raised above a transition temperature of the shape-memory material, thereby generating a gripping force against the bone circumference.

[0026] At least two wings may be placed along the length of the spine.

[0027] The spine may be a longitudinal plate. The spine may have a width between about 5mm to 20mm (e.g., about 10 mm). The spine may have a length between about 30mm to 300mm. The spine may have a thickness between about 2 mm to about 8 mm.

[0028] The spine may have intermittent notches at both sides of the edges along the length to permit lateral bending (e.g., as required by the surgeon). The notches may be spaced about 5 mm to 30 mm from each other along the length.

[0029] The spine may have intermittent holes through the longitudinal centerline along the length to allow for screw fastening of the device to the bone at various locations (e.g., as required by the surgeon). The holes may be spaced about 5 mm to 20 mm from each other along the length.

[0030] The spine may have intermittent magnets or slots at the bottom side adjacent to the bone along the length to permit attachment to the wings (e.g., as required by the surgeon). The magnets or slots may be spaced about 10 mm to 30 mm from each other along the length.

[0031] The wings may have a width between about 2 mm to about 6 mm (e.g., about 4 mm). The wings may have a length between about 20 mm to about 100 mm (e.g., about 70 mm). The wings may have a thickness between about 1 mm to about 3 mm (e.g., about 1.5 mm).

[0032] The spine may be formed from a spine metal. The spine metal may comprise titanium or a titanium alloy.

[0033] A said wing may be formed from a wing metal. The wing metal may comprise an alloy (e.g., nickel titanium alloy). The nickel titanium alloy may be Nitinol.

[0034] The surface of the spine and wing may comprise an antimicrobial surface texturing, e.g., to mitigate possibility of infection. The surface of the spine and wing may be grossly textured to improve grip.

[0035] The surface of the spine and wing may comprise osseointegration promoting surface texturing to mitigate device separation from the bone. The osseointegration promoting surface texturing may be present on one or more surfaces configured to be in contact with the bone when in place.

[0036] The surface texturing may be formed by using laser technology.

[0037] Biomechanical strength: With the unique property of combining the wing clamps to a more traditional plate and screw fixation the combination may provide a biomechanically superior construct than the traditional plate and screws alone.

[0038] While the traditional plate and screw construct supports the fractured bone in two planes the present device may support a fracture in 3 planes (e.g. transverse to orthogonal x-, y- and z-axes). The present device may provide support against rotational forces (e.g., torsion around the bone axis).

[0039] The wings may be placed along the plate in positions determined by the surgeon to best reduce and constrain the fracture. The wings may be integrated into the plate via differing joints. Designs may be variable with slots on the bottom of the plate that allow adjustment of the wing and plate positions, dovetail slots that secure the wings in the plate and / or multiple screw holes that allow variable positions on the plate. The wings may also be integral with the spine and made from a single piece. The screwdriver can also insert a screw to connect the wing to the spine and or to the bone either unicortically or bicortically.

[0040] A screwdriver or clamp may be used to hold the wing while putting it on the fractured bone which will be removed once the temperature increase has caused the wing clamp to contract towards the original shape. The screwdriver can also help adjust the wing position on the bone. A locating pin may also be used to align the wing and spine until the wing is appropriately placed.

[0041] The interior surface of the spine member and / or wings may be textured as in ridges or spikes to better grip the bone.

[0042] The screw holes may have various shapes and sizes and may be locking or nonlocking.

[0043] The wings may have a substantially uniform cross section along their length. The wings may have a rectangular cross section. The wings may have a flat inner surface(e.g., the surface facing the bone in use). The wings may have a flat outer surface (opposite the inner surface).

[0044] The device may be used to secure a clavicle fracture. The device may be used to address other bone fractures i.e., of long or flat bones such as the fibula, tibia, femur, radius, ulna, humerus, carpels, metacarpals, ribs etc.BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the Detailed Description section below, one or more embodiments of the present technology are described in relation to the attached figures. These embodiments are intended to provide a better understanding of the invention, how the invention may be put into practice, and to demonstrate some of the advantages of the invention. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention. Similar reference numerals indicate similar components.Figure 1 is a perspective view of an embodiment of the internal fixation device in an open configuration positioned adjacent to a bone.Figures 2a-d are perspective views of the embodiment of figure 1 in a closed configuration engaging with and gripping a bone.DETAILED DESCRIPTIONIntroduction

[0046] Although use of plates and screws continue to be effective in fixing bone fractures, there continues to be a need for improved surgical fastening devices used in orthopedic surgery that enhances their implementation and performance, while reducing surgical trauma. The present technology is intended to advance fracture management care in the field of orthopaedic surgery.

[0047] Internal fixation devices described herein comprise built in wings which act as clamps that work in 3 planes of fixation. Certain embodiments may combine the plate and screw fixation with the reduction clamps. The clamps use a shape-memory alloy (e.g. Nickle -Titanium, Ni-Ti) that is temperature controlled.

[0048] Nickel -Titanium has many qualities that are useful for use in a fixation clamp. Firstly, it has the ability to be shaped to a position and trained to return to that position ata set temperature (e.g., 35 degrees Celsius, or just below body temperature). Below this transition temperature (e.g., at room temperature) the wing clamp can be opened to allow it to fit around the fractured bone and then will clamp down on the bone when heated to 35 degrees Celsius. In some embodiments, the transition temperature is between 25-35 degrees Celsius.

[0049] Secondly this metal has sufficient strength to be used in fracture fixation. It has similar strength characteristics to Titanium which is commonly used in traditional plate fixation.

[0050] Lastly, from a safety point of view, Nickel Titanium is commonly used in medical appliances in the human body such as in cardiac stents and dental implants. These other products that have FDA approval and are used already in medicine.

[0051] Internal fixation devices described herein may be applied to the bone with a screwdriver and then the screwdriver would be removed once the wing is activated with an increase in temperature to 35 degrees Celsius. This wing would be left in situ during fracture healing and often permanently. Multiple wings can be placed along the fracture to hold the reduction. The treated wing shape and diameter may be smaller than the bone being fixed so there will be a constant clamping affect throughout healing.

[0052] The spine member may be able to attach to the wing clamp with screw fixation strengthening the construct considerably. Lastly screws can thread through the plate, wing and the width of the bone to further strengthen the construct.

[0053] To summarize, the wing clamps can be used independently of the plate and screw fixation or with the plate and screw fixation including or not having screws go through the fractured bone.

[0054] Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present invention.

[0055] One of the present inventors is a materials scientist who conceived of the concept of using a smart material such as Nitinol to reposition and secure broken / fractured bones during open reduction procedure. Several common bone fractures have been identified that would greatly benefit from this concept. Currently, many of these bone fractures are reduced or repositioned into their proper alignment and held together with implants such as plates, screws, nails and wire. With this connection holding the broken bones together as they heal, patients usually enjoy a positive surgical outcome. The screws are often left in the bone even after healing and do not result in complications for most patients. However, problems can arise. For instance, the hole created to sustain the screw can trigger weakness in the bone and surrounding area, can shift to another position, or can even be noticeable at the skin’s surface. Even though most screws stay in place, these issues often mean that a screw must be removed.

[0056] It will be appreciated that the surgeon may have a selection of wing sizes and geometries, similar to traditional plate kits, to optimize the reduction and fixation. I.e., the wings may be releasably connectable to the spine member to allow the user to quickly assemble an internal fixation device by connecting suitable wing to the spine member.Internal Fixation Device

[0057] Figure 1 shows an embodiment 10 of the internal fixation device in an open configuration as it is positioned next to a bone. Figures 2a-d show various views of the embodiment of the internal fixation device in a closed configuration as it is gripping a bone.

[0058] The internal fixation device comprises: an elongate spine member 11 ; and one or more elongate wings 12 connected the spine member in a transverse orientation.

[0059] The elongate wings comprise shape-memory alloy, such that, when the elongate wings are below a transition temperature, the wings are bendable to be in an open configuration in which the wings extend laterally away from the elongate spine member such that an interior surface of the spine member can be positioned adjacent to a bone. This is shown in figure 1.

[0060] When the elongate wings are heated above a transition temperature, the wings are biased towards a closed configuration in which the elongate wings are bent inwardly towards the interior surface so as to grip the bone.

[0061] It will be appreciated that the spine member in this embodiment has a greater rigidity than the wings below the transition temperature (and also above the transitiontemperature). This rigidity means that the spine can be shaped to match the shape of the bone, and to provide structural support to the bone.

[0062] In this embodiment, the internal fixation device comprises multiple (four in this case) pairs of elongate wings, each pair of elongate wings comprising two wings extending in opposite directions laterally from the same position on the elongate spine member.

[0063] As shown in figure 1 , the spine member comprises intermittent notches at both sides of the edges along the length to facilitate bending. That is, these notches reduce the rigidity of the spine member at these points, allowing the spine member to be bent. This allows a standard length of spine to be shaped to match a specific bone.

[0064] The spine member, in this embodiment, comprises intermittent holes 14 along the length to allow for screw fastening (e.g. to the bone). The wings and the screws may provide complementary methods of securely fastening the device to the bone to provide the required support.

[0065] The spine member may comprise intermittent magnets and / or slots 13 on an interior side along the length to permit attachment to the wings.

[0066] In this embodiment, the spine member comprises a titanium alloy. Each wing Is formed from a nickel titanium alloy, in particular, Nitinol.

[0067] In other embodiments, one or more surfaces of the internal fixation device comprises an antimicrobial surface texturing and / or an osseointegration promoting surface.

[0068] The wing slots may be configured to allow the wings to pivot (e.g., about a “screw” axis perpendicular to both the elongate spine axis, and the elongate wing axis). That is, the wings are extend at 90 degrees to the spine axis, but some pivoting may be required to adjust this angle to allow the wings to better grip the bone. To facilitate this, the wing slots may have angled walls to allow for pivoting of the wings when near the wall of the slot. The width of the slot may be larger than the width of the wing to facilitate pivoting (see for example, figures 1 and 2d).Advantages

[0069] The technology described herein is expected to be used in a number of different procedures, including, but not limited to open reduction and internal fixation of clavicle fractures. Comminuted and / or displaced clavicle fractures require surgery to realign the collarbone. Surgery usually includes using plates, screws or rods to hold the bone in placewhile it heals. Although clavicle surgery in patients with fracture repair has low rates of complications such as infection, malunion or non-union, there could be enhancements made to the existing implant device to mitigate infection, aid the surgeon in realigning the bone and, to reduce the number of clavicle screws. Fewer screws could lead to faster recovery, less chance of complications such as iatrogenic vascular injury, without compromising on the implant prominence.

[0070] Embodiments of the gripping device which are formed of nitinol have the advantage of being approvable for in vivo human use. The constructions described herein provide alignment and holding the fractured bone and can be conveniently manufactured at large scale for great economic benefit. The transition temperature for the shapememory conversion may be optimized to occur within a certain range including a normal human body temperature so that the conversion from the original bent configuration towards the flat configuration occurs at an optimal point in time during the typical duration of the procedure used to deploy the bone gripping device.

[0071] Using the shape memory material in the wings allows the wings to have a relatively simple shape, and unitary construction.

[0072] The system may be modular in that the wings and spine members can be releasably attached to each other, thereby allowing different wings to be interchangeably used with different wings to allow the surgeon to create a fixation device best suited to the specific bone, and to the type of fracture.

[0073] A modular approach to fracture reduction and fixation may also allow for the plate to be removed irrespective of the wings once the fracture is healed.

[0074] A modular approach allows the system to be applied to a range of bones, and bone fractures.

[0075] Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.

Claims

CLAIMS1. An internal fixation device comprising: an elongate spine member; one or more elongate wings connected to the spine member in a transverse orientation; wherein the one or more elongate wings comprise shape-memory alloy, such that: when the one or more elongate wings are below a transition temperature, the wings are bendable to be in an open configuration in which the wings extend laterally away from the elongate spine member such that an interior surface of the spine member can be positioned adjacent to a bone; and when the one or more elongate wings are heated above a transition temperature, the wings are biased towards a closed configuration in which the elongate wings are bent inwardly towards the interior surface so as to grip the bone.

2. The internal fixation device according to claim 1 , wherein the elongate spine member has a greater rigidity than the wings below the transition temperature.

3. The internal fixation device according to any one of claims 1-2, wherein the internal fixation device comprises one or more pairs of elongate wings, each pair of elongate wings comprising two wings extending in opposite directions laterally from the same position on the elongate spine member.

4. The internal fixation device according to any one of claims 1-3, wherein the spine member comprises intermittent notches at both sides of the edges along the length to facilitate bending.

5. The internal fixation device according to any one of claims 1-4, wherein the spine member comprises intermittent holes along the length to allow for screw fastening.

6. The internal fixation device according to any one of claims 1-5, wherein the spine member has intermittent magnets and / or slots on an interior side along the length to facilitate location of the one or more wings with respect to the spine member.

7. The internal fixation device according to any one of claims 1-6, wherein the spine member comprises titanium or its alloy.

8. The internal fixation device according to any one of claims 1-7, wherein the one or more wings comprises nickel titanium alloy.

9. The internal fixation device according to any one of claims 1-8, wherein the one or more wings comprises Nitinol.

10. The internal fixation device according to any one of claims 1-9, wherein a surface of the internal fixation device comprises an antimicrobial surface texturing.

11. The internal fixation device according to any one of claims 1-10, wherein a surface of the internal fixation device comprises an osseointegration promoting surface texturing.

12. The internal fixation device according to any one of claims 10-11 , wherein the texturing is formed by using laser technology.

13. The internal fixation device according to any one of claims 1-12, wherein the transition temperature is between 25°C and 35°C.

14. The internal fixation device according to any one of claims 1-13, wherein at least one of the wings is attached to the spine member using a screw.

15. Use of an internal fixation device according to any one of claims 1-14 to secure a bone fracture.

16. A method of manufacturing the internal fixation device according to any one of claims 1-14, wherein the method comprises: providing the elongate spine member; and connecting the one or more elongate wings to the spine member in a transverse orientation.

17. The method according to claim 16, wherein the method comprises setting the closed configuration of the one or more wings.

18. A kit comprising: an elongate spine member; one or more elongate wings connectable to the spine member in a transverse orientation; wherein the one or more elongate wings comprise shape-memory alloy, such that:when the one or more elongate wings are below a transition temperature while connected to the spine member in a transverse orientation, the wings are bendable to be in an open configuration in which the wings extend laterally away from the elongate spine member such that an interior surface of the spine member can be positioned adjacent to a bone; and when the one or more elongate wings are heated above a transition temperature while connected to the spine member in a transverse orientation, the wings are biased towards a closed configuration in which the elongate wings are bent inwardly towards the interior surface so as to grip the bone.

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