STAPLES FOR GENERATING AND APPLYING COMPRESSION WITHIN A BODY

Abstract

Apparatus for generating, applying and maintaining compression to a site in a human or animal body, the apparatus comprising: a staple comprising: a bridge configured to be elastically bendable; a first leg connected to the bridge by a first hinge region configured to be elastically bendable; and a second leg connected to the bridge by a second hinge region configured to be elastically bendable; wherein the first hinge region comprises a first hole configured to mate with a first element of a delivery device and the second hinge region comprises a second hole configured to mate with a second element of a delivery device; and wherein the first and second legs are angled toward one another when they are in an unstrained state; whereby, when the staple is mounted to a delivery device so that the first hole of the first hinge region mates with a first element of a delivery device and the second hole of the second hinge region mates with a second element of a delivery device, and when the delivery device applies a force to the bridge of the staple so as to reconfigure the bridge of the staple, the first and second legs are pivoted away from one another toward a parallel disposition.

Claims

1. A delivery device comprising: a) a body having an internal threaded region configured to mate with a threaded screw; b) a handle mounted to a proximal end of the threaded screw; and c) a plunger; wherein when the threaded screw is advanced into the body  i) a distal end of the threaded screw pushes against a proximal end of the plunger, and  ii) a distal end of the plunger is configured to engage and bend an elastic bridge of a releasably mounted staple.

2. The delivery device of claim 1, wherein the staple comprises nitinol.

3. The delivery device of claim 1, wherein the staple comprises polyether ether ketone (PEEK).

4. A delivery device comprising: a) a body having an internal threaded region configured to mate with a threaded screw; b) a handle mounted to a proximal end of the threaded screw; and c) a plunger; wherein when the threaded screw is advanced into the body  i) a distal end of the threaded screw pushes against a proximal end of the plunger, and  ii) a distal end of the plunger is configured to engage and bend an elastic bridge of a releasably mounted staple to become more linear.

5. The delivery device of claim 4, wherein the staple comprises nitinol.

6. The delivery device of claim 4, wherein the staple comprises polyether ether ketone (PEEK).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein:

[0065] FIG. 1 is a schematic view of a novel staple formed in accordance with the present invention, wherein the staple comprises a bridge which is capable of being elastically bent and legs which are capable of being elastically pivoted about elastic hinge regions, and further wherein the staple is shown in its unstrained condition;

[0066] FIG. 2 is a schematic view of the novel staple shown in FIG. 1, wherein the bridge of the staple has been elastically bent (i.e., made to be more linear) and the legs of the staple have been elastically pivoted outwards (e.g., by bending at the elastic hinge regions) so as to be perpendicular to the bridge;

[0067] FIG. 3 is a schematic view showing how the elastically bent staple of FIG. 2 will have its legs “kick inward” when the strain on the staple is removed;

[0068] FIGS. 4, 4A, 4B, 5, 6, 6A and 6B are schematic views showing a novel delivery device which may be used with the novel staple shown in FIG. 1 to strain and constrain the staple (e.g., with the staple legs perpendicular to the staple bridge);

[0069] FIGS. 7 and 8 are schematic views showing the delivery device of FIGS. 4, 4A, 4B, 5, 6, 6A and 6B being used with the novel staple shown in FIG. 1 to elastically bend the bridge of the staple and elastically pivot the legs of the staple (e.g., by bending at the elastic hinge regions);

[0070] FIGS. 9 and 10 are schematic views showing how the novel staple of FIG. 1 may be used to generate and maintain compression between bone fragments so as to aid in fracture healing;

[0071] FIGS. 11-13 are schematic views showing another novel staple formed in accordance with the present invention, wherein the novel staple comprises a bridge which is capable of being elastically bent and legs which are capable of being elastically pivoted about elastic hinge regions—the novel staple of FIGS. 11-13 has a concave bridge specifically engineered to match the anatomy of the fracture site (e.g., an Akin Osteotomy site), where FIG. 11 shows the staple in its unstrained condition, FIG. 12 shows the staple strained with its bridge elastically bent (i.e., made to be more concave) and its legs pivoted outwards (e.g., by bending at the elastic hinge regions) so as to be perpendicular to the bridge, and FIG. 13 is a schematic view showing how the elastically bent staple of FIG. 12 will have its legs “kick inward” when the strain on the staple is removed;

[0072] FIGS. 14-16 are schematic views showing still another novel staple formed in accordance with the present invention, wherein the novel staple comprises a sloped bridge which is capable of being elastically bent and legs which are capable of being elastically pivoted about elastic hinge regions—the novel staple of this design has a slanted bridge specifically engineered to match the anatomy of the fracture site (e.g., an Akin Osteotomy site), where FIG. 14 shows the staple in its unstrained condition, FIG. 15 shows the staple strained with its bridge elastically bent (i.e., made to be more sloped) and its legs pivoted outwards (e.g., by bending at the elastic hinge regions) so as to be parallel with each other, and FIG. 16 is a schematic view showing how the elastically bent staple of FIG. 15 will have its legs “kick inward” when the strain on the staple is removed;

[0073] FIGS. 17-19 are schematic views showing yet another novel staple formed in accordance with the present invention, wherein the novel staple comprises a bridge which is capable of being elastically bent and legs which are capable of being elastically pivoted about elastic hinge regions—the staple of this design has a stepped bridge specifically engineered to match the anatomy of the fracture site (e.g., sliding calcaneal osteotomies, calcaneocuboid fusions, Lapidus procedures, etc.), where FIG. 17 shows the staple in its unstrained condition, FIG. 18 shows the staple strained with its bridge elastically bent (i.e., made to be more linear) and its legs pivoted outwards (e.g., by bending at elastic hinge regions) so as to be perpendicular to the bridge, and FIG. 19 is a schematic view showing how the elastically bent staple of FIG. 18 will have its legs “kick inward” when the strain on the staple is removed;

[0074] FIGS. 20-22 are schematic views showing another novel staple formed in accordance with the present invention, wherein the staple comprises a malleable bridge which is capable of being plastically bent (i.e., to take a set) and legs which are capable of being elastically pivoted about elastic hinge regions—FIG. 20 shows the staple in its unstrained condition, FIG. 21 shows the staple strained with its malleable bridge plastically bent (i.e., made to take a set so as to be concave to match the fracture site anatomy) and its legs pivoted outwards (e.g., by bending at elastic hinge regions) so as to be perpendicular to the bridge, and FIG. 22 is a schematic view showing how the elastically bent staple of FIG. 21 will have its legs “kick inward” when the strain on the staple is removed; and

[0075] FIG. 23 shows how the holes at the hinge region of the staple may be used by the surgeon to attach sutures for tying down tissue (e.g., ligaments, tendons, etc.).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Novel Staple Comprising Bridge With Two Elastic Hinge Regions Incorporating Mounting Holes

[0076] Looking first at FIG. 1, there is shown a novel staple 5 which is able to bring bone fragments into close proximity with each other, generate a compressive load across the fracture line, and maintain a compressive load across the fracture line while healing occurs. Staple 5 can be fully seated against the bone fragments without needing to be tamped after being released from the delivery device.

[0077] Novel staple 5 is preferably manufactured from a shape memory material (e.g., a material capable of exhibiting superelasticity and/or a temperature-induced shape change). The shape memory material may comprise a metal alloy (e.g., Nitinol) or a polymer (e.g., appropriately processed PEEK). Alternatively, staple 5 may be manufactured from another suitable material, e.g., stainless steel, titanium, etc. Staple 5 is designed to reduce fractures and generate and maintain compression between bone fragments (e.g., across a fracture line) so as to aid in fracture healing. Staple 5 comprises an elastic bridge 10 and two elastic legs 15. Bridge 10 and legs 15 meet at a pair of curved hinge regions 20 which are also elastic. Hinge regions 20 have holes 25 passing therethrough. Holes 25 may be round or may have other configurations consistent with the present invention. Legs 15 may have barbed teeth 30 to help the legs of the staple grip the bone after implantation into the bone and prevent the legs of the staple from working their way back out of the bone. In its unrestrained state, bridge 10 is bowed upwardly in the manner shown in FIG. 1. In the unrestrained state, legs 15 of staple 5 are elastically pivoted inwardly at elastic hinge regions 20 with an angle of less than 90° (relative to bridge 10). By way of example but not limitation, in one preferred form of the invention, legs 15 extend at an angle of about 65° to the longitudinal axis of bridge 10 when in their unrestrained state.

[0078] Prior to implantation, bridge 10 of staple 5 can be reversibly bent (i.e., bent to nearly linear) and legs 15 of staple 5 can be reversibly pivoted at elastic hinge regions 20 (e.g., by bending at the elastic hinge regions 20) to a position substantially perpendicular to bridge 10 (FIG. 2) so as to allow for insertion of the legs of the staple into a prepared fracture site, with the bridge of the staple spanning across the fracture line (see below). Note that where staple 5 is formed out of Nitinol, elastic deformations of up to approximately 8% are achievable. A delivery device (see below) can be used to elastically bend bridge 10 and pivot legs 15 at elastic hinge regions 20 (e.g., by bending at the elastic regions 20), constrain and hold the staple in its strained state prior to implantation, and then insert the staple into the prepared fracture site.

[0079] Upon insertion of the strained staple 5 into the prepared fracture site, the constraint on bridge 10 and legs 15 is removed, whereupon staple 5 attempts to return to its original un-restrained state (FIG. 3), thereby generating a compressive load across the fracture line and maintaining that compressive load across the fracture line while healing occurs.

[0080] Looking next at FIGS. 4, 4A, 4B, 5, 6, 6A, 6B, 7 and 8, there is shown a novel delivery device 35 which may be used to selectively bend bridge 10 and to selectively pivot legs 15 of staple 5 at elastic hinge regions 20 (e.g., by bending at the elastic hinge regions 20). Delivery device 35 comprises a body 40 having an internal threaded region 45 (FIG. 6) configured to mate with threaded screw 50. Threaded screw 50 has a handle 55 mounted to its proximal end. Advancing threaded screw 50 into body 40 (e.g., by selectively rotating handle 55 so as to selectively rotate threaded screw 50 such that the threads of threaded screw 50 engage internal threaded region 45) causes the distal end of threaded screw 50 to push against the proximal end of a plunger 60. The distal end of plunger 60 engages elastic bridge 10 of staple 5. When plunger 60 is moved distally (i.e., by moving threaded screw 50 distally by rotating handle 55), the distal end of plunger 60 engages elastic bridge 10 of staple 5 and elastically bends elastic bridge 10 into a more linear configuration. Staple 5 is releasably mounted to delivery device 35 by a pair of pins 65 which are mounted to two arms 70 which are each pivotally mounted to body 40 of delivery device 35 by a pivot pin 75. Pins 65 are received within holes 25 formed in staple 5. When plunger 60 is moved distally against elastic bridge 10 of staple 5, the deforming (i.e., straightening) bridge 10 of staple 5 causes arms 70 of delivery device 35 to pivot outwardly, with elastic hinge regions 20 of staple 5 bending about pins 65 so as to pivot staple legs 15 outwardly.

[0081] More particularly, and looking now at FIGS. 7 and 8, when staple 5 is mounted to pins 65 of delivery device 35 (i.e., with pins 65 being received within holes 25 of staple 5) and handle 55 is rotated so as to advance threaded screw 50 distally, plunger 60 is also advanced distally, whereby to push against elastic bridge 10, causing elastic bridge 10 to bend and become more linear, and causing arms 70 of delivery device 35 to articulate (i.e., pivot) outwardly. As this occurs, elastic hinge regions 20 of staple 5 bend about pins 65, causing elastic legs 15 to be pivoted about elastic hinge regions 20 so as to be oriented generally perpendicular to elastic bridge 10 (FIG. 8).

[0082] Note that staple 5 is configured so that the force that is generated as staple 5 reconfigures (i.e., as bridge 10 and legs 15 attempt to return back to their original disposition) is less than the “tear through” force of the bone receiving legs 15, i.e., staple 5 is specifically engineered so as to not “tear through” the bone tissue when staple 5 attempts to return to its original, unbiased shape. The compressive forces generated by staple 5 as staple 5 attempts to reconfigure (i.e., as bridge 10 contracts and as elastic legs 15 of staple 5 attempt to pivot inboard toward one another about elastic hinge regions 20) can be controlled by modulating the material properties of staple 5 and/or the geometry of staple 5.

[0083] By way of example but not limitation, the percentage of cold work in the shape memory material forming staple 5 affects the compressive force that is generated by the reconfiguring staple 5. As the percentage of cold work increases, the compression force that is generated decreases. In one preferred form of the present invention, staple 5 has between about 15% and about 55% cold work in order to control the recovery force (i.e., the compressive force generated by bridge 10 and legs 15 as staple 5 reconfigures) of staple 5; however, if desired, other degrees of cold work may be used, and/or the material comprising staple 5 may not be cold worked at all.

[0084] By way of further example but not limitation, another material property that affects the compression force generated by staple 5 as the staple reconfigures is the temperature differential between the body that staple 5 will be implanted into (assumed to be approximately 37° C., which is the temperature of a human body) and the austenite finish temperature of the shape memory material forming staple 5. A smaller temperature differential between the two will result in staple 5 generating a smaller compressive load as staple 5 reconfigures; conversely, a larger temperature differential between the two will result in staple 5 generating a larger compressive load as staple 5 reconfigures. The shape memory material that staple 5 is made out of should, preferably, have an austenite finish temperature of greater than about −10° C., resulting in a temperature differential of about 47° C. when the staple is implanted (assuming that the staple is implanted in a human body).

[0085] By way of further example but not limitation, staple geometry also affects the compression forces generated as staple 5 reconfigures. More particularly, the cross-sectional areas of elastic bridge 10, elastic hinges 20 and elastic legs 15 affect the compression forces generated by the reconfiguring staple 5. As the cross-sectional areas increase, the compression forces that the reconfiguring staple 5 generates also increase.

[0086] Elastic legs 15 of staple 5 are critical for transmitting the compression force to the bone without “tearing through” the bone. The height, width, and length of the staple legs, and the geometry of the staple legs, are all significant factors relating to the staple's ability to not “tear through” the bone. Elastic legs 15 having greater surface area are better able to distribute the compression force and thus resist “tearing through” the bone.

[0087] FIG. 9 shows how staple 5 may be used to reduce a fracture and generate and maintain compression between bone fragments 80 and 85.

[0088] More particularly, the fracture 90 which is to be fused is first re-approximated and reduced. A drill guide (not shown) of the sort well known in the art is used to drill two holes 95 the correct distance apart to accommodate the legs 15 of staple 5. Staple 5 is mounted to pins 65 of delivery device 35, and delivery device 35 is used to bend bridge 10 and straighten legs 15 of staple 5 in the manner discussed above (i.e., by turning handle 55 to advance plunger 60 which is used to bend bridge 10 and pivot legs 15 at elastic hinge regions 20). While still mounted to pins 65 of delivery device 35, legs 15 of staple 5 are placed into the pre-drilled holes 95. Staple 5 is then released from pins 65 of delivery device 35, i.e., by turning handle 55 in the opposite (e.g., counter-clockwise) direction and sliding staple 5 off of pins 65. This allows the bent bridge 10 and pivoted legs 15 of staple 5 to attempt to return (reconfigure) to their un-bent configuration, thereby applying compression across fracture 90.

[0089] Note that in the preferred form of the invention, staple 105 is designed to generate and maintain compression between both the cortical bone and the cancellous bone of the bone fragments so as to promote effective healing. In this respect note also that, while bridge 10, elastic hinges 20 and the proximal (i.e., bridge-side) portions of legs 15 typically engage cortical bone, the pivoting nature of the reconfiguring distal portions of legs 15 will help apply enhanced compressive forces to the cancellous bone (i.e., the interior bone) of the bone fragments.

[0090] Significantly, it should be appreciated that since staple 5 is mounted to delivery device 35 via pins 65 being inserted into holes 25, staple 5 can be fully inserted into pre-drilled holes 95 with bridge 10 in direct contact with bone fragments 80 and 85. Tamping is not needed in order to fully seat staple 5 (FIG. 10).

[0091] It should also be appreciated that, if desired, staple 5 can be used to attach soft tissue to bone (e.g., to attach a rotator cuff to bone).

[0092] In some circumstances it can be desirable to modify delivery device 35 so as to ensure that legs 15 cannot be pivoted at hinge regions 20 beyond 90 degrees (relative to the longitudinal axis of bridge 10) when legs 15 of staple 5 are pivoted outboard. In other circumstances, it may be desirable for delivery device 35 to allow legs 15 of staple 5 to be pivoted outboard less than, or greater than, 90 degrees to allow insertion into slightly mispositioned (or angled) drill holes 95.

[0093] It should be appreciated that following implantation, if desired, delivery device 35 can also be used to remove staple 5 from the bone. More particularly, delivery device 35 can be used to re-engage staple 5 at the holes 25 (i.e., by inserting pins 65 of delivery device 35 into holes 25 of staple 5) in the hinge regions 20 of staple 5. Turning handle 55 (e.g., clockwise) causes plunger 60 to bend staple bridge 10 and to reconfigure staple 5 such that bridge 10 is substantially perpendicular to staple legs 15. Staple 5 can then be removed from the bone by pulling the staple out perpendicular to the bone.

[0094] Additionally, staple delivery device 35 allows the surgeon to “sense” how much compression staple 5 will exert on the bone when it is released from delivery device 35 and attempts to reconfigure. More particularly, as the surgeon turns handle 55 to straighten bridge 10 and open staple legs 15 (e.g., by turning handle 55 clockwise), handle 55 requires greater levels of torque as staple 5 is opened (i.e, as bridge 10 is pushed down and legs 15 are pivoted outboard), thereby providing a degree of tactile feedback to the surgeon. The torque that the surgeon applies to handle 55 is proportional to the compression that staple 5 will exert on the bone as the staple reconfigures.

[0095] Thus delivery device 35 also allows the surgeon to ascertain and control how much compression staple 5 will exert when the staple is released from delivery device 35. The greater the degree to which bridge 10 is straightened and legs 15 of staple 5 are opened (i.e., pivoted outboard), the more compressive force staple 5 will exert on the bone when it is released from delivery device 35.

[0096] Additionally, delivery device 35 also allows the surgeon to control the rate at which staple 5 loads the bone as the staple is removed from delivery device 35. More particularly, turning handle 55 of delivery device 35 counterclockwise releases the downward (i.e., distal) force that plunger 60 exerts on bridge 10 of staple 5. This allows staple 5 to attempt to recover (i.e., reconfigure) to its original shape and apply compression across the fracture site. It may be desirable to allow the surgeon to be able to control this “release rate” so that the bone is not damaged as staple 5 reconfigures and so that staple 5 remains in the desired location.

[0097] In one preferred form of the invention, staple 5 and delivery device 35 are provided in the form of a sterilized kit. Staple 5 may be “pre-loaded” (i.e, mounted) onto delivery device 35 (i.e., with pins 65 of delivery device 35 extending through holes 25 of staple 5). Staple 5 may be mounted on delivery device 35 in an unconstrained or a constrained state. The kit may include additional instruments to aid in the implantation of the staple (e.g., k-wire, drill bit, staple size guide, etc.).

EXAMPLE

[0098] The compressive force generated by staples of the present invention formed out of Nitinol with greater than 20% cold work are able to generate 50 to 100 Newtons of force depending on the staple dimensions. This is more than twice the compression force able to be generated by conventional staples of a similar size.

Alternative Configurations of Novel Staple Formed in Accordance With the Present Invention

[0099] Looking now at FIGS. 11-19 it should be appreciated that staple bridge 10 may be formed so as to have a different configuration. By way of example but not limitation, it may be beneficial for staple bridge 10 to have a concave geometry (FIGS. 11-13), such that when bridge 10 of staple 5 is reversibly bent (i.e., so that legs 15 are pivoted so that they are parallel to each other), bridge 10 can bend downwardly, i.e., so as to become more concave (FIG. 12). Upon insertion of the strained staple 5 across the prepared fracture site, the constraint on bridge 10 and hinges 20 is removed, whereupon staple 5 attempts to return (i.e., reconfigure) to its original unrestrained state (FIG. 13), thereby generating a compressive load across the fracture line and maintaining that compressive load across the fracture line while healing occurs. By way of example but not limitation, it may be beneficial to provide a staple 5 having a concave bridge 10 for the treatment of fractures where the anatomy is “hour-glass” shaped (e.g., in an Akin Osteotomy).

[0100] It may also be desirable to provide a staple 5 having a bridge 10 formed with a sloped geometry (FIG. 14). In this form of the invention, legs 15 can be elastically pivoted so as to be parallel to one another (FIG. 15). Upon insertion of the strained staple 5 into the prepared fracture site, the constraint on bridge 10 and hinges 20 is removed, whereupon staple 5 attempts to return to its original un-restrained state (FIG. 16), thereby generating a compressive load and maintaining that compressive load while healing occurs. It may be desirable to provide staple 5 having this configuration for the treatment of fractures where the anatomy is non-linear (e.g., at the metaphyseal flares).

[0101] It may also be desirable to provide staple 5 with bridge 10 having a stepped geometry (FIG. 17). In this form of the invention, when staple 5 is reversibly strained (i.e., so that legs 15 are pivoted outboard so as to be parallel to each other), bridge segments 10a and 10b are parallel to each other (FIG. 18). Upon insertion of the strained staple 5 into the prepared fracture site, the constraint on bridge 10 and hinges 20 is removed, whereupon staple 5 attempts to return (i.e., reconfigure) to its original un-restrained state (FIG. 19), thereby generating a compressive load across the fracture line and maintaining that compressive load across the fracture line while healing occurs. It may be desirable to provide a staple 5 having this configuration for the treatment of fractures where the anatomy is uneven (i.e., sliding calcaneal osteotomies, calcaneocuboid fusions, Lapidus procedures, etc.).

Novel Staple Having a Malleable Bridge Which Is Plastically Deformable to Take a Set

[0102] It may also be desirable to provide a staple 5 having a malleable bridge 10 which is plastically deformable so as to be able to take a set (FIG. 20). This allows the surgeon to shape staple bridge 10 in order to conform to the anatomy of the patient. With this form of the invention, delivery device 35 can be used to deform/shape staple bridge 10. When a staple of this configuration has a force applied to its bridge 10 so that staple legs 15 are pivoted so as to be parallel to each other, malleable bridge 10 is plastically deformed so as to take a set (FIG. 21). The more staple legs 15 are opened (i.e., pivoted outboard), the more staple bridge 10 is plastically deformed. Upon insertion of the strained staple 5 into the prepared fracture site, elastic hinges 20 attempt to return staple legs 15 to their original un-restrained state while staple bridge 10 remains deformed (FIG. 22), thereby generating a compressive load and maintaining that compressive load across the fracture line while healing occurs. A staple of this configuration may be beneficial for the treatment of fractures where the anatomy is uneven (e.g., in an Akin Osteotomy).

Additional Use for Staple Mounting Holes

[0103] While holes 25 are primarily used for releasably mounting staple 5 to delivery device 35 (i.e., via pins 65), holes 25 also may be used after implantation to aid the surgeon with tying ligaments and/or tendons directly down to the bone (FIG. 23). Typically, a surgeon would use a suture anchor, bone tunnel or other method/device known in the art to re-secure a ligament and/or tendon to the bone. It should be appreciated that the staple of the present invention provides the surgeon with holes 25 which may be used to tie ligaments and/or tendons directly to the bone. This allows the surgeon to avoid having to use an additional implant or perform an additional procedure to achieve the same outcome.

Additional Applications

[0104] In the foregoing disclosure, novel staple 5 and novel delivery device 35 are discussed in the context of rejoining a broken bone. However, it should be appreciated that novel staple 5 and novel delivery device 35 may be used to promote joinder of substantially any two (or more) bone segments, e.g., they may be used to reduce openings and maintain compression between bone segments in osteotomies, or they may be used for inducing fusion across the bones of a joint in an arthrodesis, etc.

Modifications of the Preferred Embodiments

[0105] It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.