Patent Description:
<CIT> relates to a staple comprising a bridge configured to be elastically stretchable with a first leg connected to said bridge and configured to be elastically bendable and a second leg connected to the bridge and configured to be elastically bendable.

In the field of orthopedic surgery, it is common to rejoin broken bones. The success of the surgical procedure often depends on the ability to reapproximate the fractured bones, the amount of compression achieved between the bone fragments, and the ability to sustain that compression over a period of time. If the surgeon is unable to bring the bone fragments into close contact, a gap will exist between the bone fragments and the bone tissue will need to fill that gap before complete healing can take place. Furthermore, gaps between bone fragments that are too large allow motion to occur between the bone fragments, disrupting the healing tissue and thus slowing the healing process. Optimal healing requires that the bone fragments be in close contact with each other, and for a compressive load to be applied and maintained between the bone fragments. Compressive strain between bone fragments has been found to accelerate the healing process in accordance with Wolf's Law.

Broken bones can be rejoined using staples. Staples are formed from a plurality of legs (typically two legs, though sometimes more) connected together by a bridge. Staples are typically manufactured from either stainless steel alloys, titanium alloys or Nitinol, a shape memory alloy. The staples are inserted into pre-drilled holes on either side of the fracture site, with the bridge of the staple spanning the fracture line.

While these staples are designed to bring the bone fragments into close contact and to generate a compressive load between the bone fragments, the staples do not always succeed in accomplishing this objective. It is widely reported that the compressive load of staples dissipates rapidly as the bone relaxes and remodels around the legs of the staples. Furthermore, current staple systems do not allow the surgeon to control the amount of compression that the staple will exert
when it is released from the delivery device, do not allow the surgeon to control the rate at which the staple loads the bone when it is removed from the delivery device, and do not allow the surgeon to control the extent to which the staple's legs are opened.

Thus there exists a clinical need for fixation devices that are able to bring bone fragments into close proximity with each other, generate a compressive load, and maintain that compressive load for a prolonged period of time while healing occurs.

Moreover, existing staples have bridges that are fixed in size, shape, and dimension, while each procedure presents a unique anatomical requirement (which is set by a combination of indication and patient-specific anatomy). Existing staples with fixed shape and dimension bridges will often sit "proud" of the cortical bone, resulting in irritated and inflamed adjacent soft tissue and, in some cases, bursitis.

Thus there also exists a clinical need for a staple with a malleable bridge that may be bent so as to conform to the unique anatomical structure of each patient and sit flush on the cortical surface of the bone.

Moreover, in the field of spine surgery, it is common to fuse adjacent vertebra. Facet fixation screws are commonly used to induce fusion. The screws are intended to stabilize the spine as an aid to fusion through bilateral immobilization of the facet joints. For transfacet fixation, the screws are inserted through the inferior articular process across the facet joint and into the pedicle. For translaminar facet fixation, the screws are inserted through the lateral aspect of the spinous process, through the lamina, through the inferior articular process, across the facet joint and into the pedicle. The current invention disclosed herein may be utilized for bilateral facet fixation, with or without bone graft, at single or multiple levels from C2 to S1 inclusive.

Thus there further exists a clinical need for fixation devices that are able to bring adjacent vertebra into close proximity with each other, generate a compressive load, and maintain that compressive load for a prolonged period of time while fusion occurs.

An exemplary staple includes a bridge, a first leg connected to the bridge and configured to be elastically deformable, and a second leg connected to the bridge and configured to be elastically deformable. The first leg and the second leg are movable between an unrestrained state in which the first leg and the second leg converge toward one another and a constrained state in which the first leg and the second leg are moved toward a parallel position when a force is applied to at least one of the bridge or the first leg and the second leg.

In a further embodiment, a bridge of a staple is elastically deformable and superelastic.

In a further embodiment, a bridge of a staple is malleable and non-superelastic.

In a further embodiment, a bridge, a first leg, and a second leg of a staple are integrally formed out of a single piece of shape memory material to establish a monolithic structure.

In a further embodiment, a shape memory material used to form a staple includes PEEK or Nitinol.

In a further embodiment, a first leg of a staple is connected to a bridge by a first hinge and a second leg is connected to the bridge by a second hinge, and the first hinge and the second hinge are elastically deformable.

In a further embodiment, a hole is formed through first and second hinges of a staple.

In a further embodiment, a bridge of a staple is convex in an unrestrained state of the staple.

In a further embodiment, each of a first leg and a second leg of a staple includes a plurality of barbed teeth.

In a further embodiment, a bridge of a staple is stretched longitudinally and legs of the staple are reversibly bent to a position that is substantially perpendicular to the bridge in a constrained state of the staple.

An exemplary surgical system includes a delivery device and a staple mountable to the delivery device. The staple is made of a shape memory material and includes a bridge, a fist leg connected to the bridge by a first hinge region, and a second leg connected to the bridge by a second hinge region. The delivery device is adapted to engage the staple either under the bridge or through holes formed in the first hinge region and the second hinge region and is adapted to move the staple from a first position in which the first leg and the second leg are convergent and a second position in which the first leg and the second leg are substantially parallel.

In a further embodiment, a delivery device includes a rotatable knob and a plunger, and rotation of the rotatable knob moves the plunger to deform a bridge of a staple.

In a further embodiment, a delivery device includes pins that engage a staple either under a bridge or through holes formed in the staple.

In a further embodiment, a delivery device includes a staple mount adapted to both longitudinally stretch a bridge and bend first and second legs of a staple.

In a further embodiment, a bridge of a staple is malleable and non-superelastic and a surgical system includes a bending device adapted to bend the bridge of the staple to a desired geometry prior to mounting the staple to a delivery device.

In a further embodiment, a bending device includes a screw mechanism movable to drive a drive element against a bridge of a staple to bend the bridge.

In a further embodiment, a delivery device includes a plier assembly having a straining fixture adapted to hold a first leg and a second leg of a staple in a position.

In a further embodiment, a surgical system includes a combination bending device and delivery device.

In a further embodiment, a combination bending device and delivery device includes a staple holder and an anvil that cooperate to bend a staple and staple grips that cooperate to engage the staple for inserting the staple into bone.

Another exemplary surgical system includes a compression screw and an internal retaining pin. The compression screw includes a shaft, a screw thread formed on a distal region of the shaft, and an enlarged head formed on a proximal region of the shaft. A portion of the shaft disposed between the screw thread and the enlarged head is capable of being stretched to an elongated state. The internal retaining pin is insertable into the compression screw for releasably holding the portion of the shaft in the elongated state.

<FIG> illustrates a staple <NUM> for bringing bone fragments into close proximity with each other, generating a greater, more uniform (i.e., across the cortical bone and the cancellous bone) compressive load across the fracture line, and maintaining that greater, more uniform compressive load for a prolonged period of time while healing occurs.

The staple <NUM> is preferably an integral, monolithic structure manufactured from a single piece of shape memory material (e.g., a material capable of exhibiting superelasticity and/or a temperature-induced shape change). The shape memory material may be a metal alloy (e.g., Nitinol) or a polymer (e.g., appropriately processed PEEK).

The staple <NUM> is designed to reduce fractures and generate and maintain greater and more uniform compression between bone fragments to aid in fracture healing. The staple <NUM> includes an elastic bridge <NUM> and two elastic legs <NUM> that extend from the bridge <NUM>. The bridge <NUM> and the legs <NUM> meet at a pair of curved hinge regions <NUM>, which are also elastic. The legs <NUM> may have one or more barbed teeth <NUM> adapted to grip into the bone after implantation and prevent the legs of the staple from working their way back out of the bone. In an un-restrained state, the legs <NUM> of the staple <NUM> are bent inward with an angle of less than <NUM>°. In an embodiment, the legs <NUM> extend at an angle of about <NUM>° to the longitudinal axis of the bridge <NUM> when in their unrestrained state.

Prior to implantation, the bridge <NUM> of the staple <NUM> can be reversibly strained outward (i.e., stretched longitudinally) and the legs <NUM> of staple <NUM> can be reversibly bent to a position substantially perpendicular to bridge <NUM> (see <FIG>) so as to allow for insertion of the legs of the staple <NUM> into a prepared fracture site. Once implanted, the stretched bridge <NUM> of the staple <NUM> spans across the fracture line. In an embodiment where the staple <NUM> is formed out of Nitinol, elastic deformations of up to approximately <NUM>% are achievable. A delivery device (described below) can be used to strain the bridge <NUM> and bend the legs <NUM>, hold the staple <NUM> in this strained state prior to implantation, and then insert the staple <NUM> into the prepared fracture site.

Upon insertion of the strained staple <NUM> into the prepared fracture site, the constraint on bridge <NUM> and the legs <NUM> is removed, whereupon the staple <NUM> attempts to return to its original un-restrained state (see <FIG>), thereby generating a greater compressive load with more uniformity along the fracture line (i.e., through the legs <NUM> and the compressive bridge <NUM>), and maintaining that compressive load for a prolonged period of time while healing occurs.

Referring next to <FIG>, an exemplary delivery device <NUM> which may be used to strain (i.e., stretch) the bridge <NUM> and bend the legs <NUM> of the staple <NUM>. The delivery device <NUM> includes two arms <NUM> which are pivotally connected together at a pivot pin <NUM>, a pair of handles <NUM> on one end for actuating the delivery device <NUM>, and a staple mount <NUM> on the other end for holding and straining the staple <NUM>. When the staple <NUM> is mounted to the staple mount <NUM> of the delivery device <NUM> and the handles <NUM> are thereafter moved toward one another, the staple mount <NUM> translates apart, thus stretching the bridge <NUM> of the staple <NUM> and bending legs <NUM> of the staple <NUM> outward to a position substantially perpendicular to the longitudinal axis of the bridge <NUM>. The delivery device <NUM> includes a locking feature <NUM> that facilitates holding the staple <NUM> in its strained state and allows for easy insertion of the staple <NUM> into a prepared fracture site. The locking feature <NUM> may be configured so that the surgeon can strain the staple to different degrees, thereby (i) enabling the surgeon to tailor the compressive force (e.g., by bending only legs <NUM>, or by bending legs <NUM> and straining bridge <NUM>), and (ii) enabling the surgeon to tailor the amount of recoverable strain established across the fracture line (e.g., by varying the amount that bridge <NUM> is stretched), depending on bone quality.

<FIG> shows a close-up of the staple mount <NUM> of the delivery device <NUM>. The staple mount <NUM> includes a channel <NUM> that receives the bridge <NUM> of staple <NUM> and two staple-stretching linkages <NUM> which sit distal to, and help define, the channel <NUM>. Radii <NUM> of the staple-stretching linkages <NUM> mate with the curved hinge regions <NUM> of the staple <NUM> when the legs <NUM> of the staple have been strained (i.e., bent) outward to a position substantially perpendicular to the longitudinal axis of the bridge <NUM>. Each staple-stretching linkage <NUM> is connected to the arms <NUM> by a pin <NUM>. The pins <NUM> slide in channels <NUM> provided on the staple-stretching linkages <NUM> (i.e., a first pin <NUM> mounted to a first staple-stretching linkage <NUM> slides in a channel <NUM> of the second staple-stretching linkage <NUM>, and a second pin <NUM> mounted to the second staple-stretching linkage <NUM> slides in the channel <NUM> of the first staple-stretching linkage <NUM>). The channels <NUM> are sized to limit the maximum amount of strain that may be imposed on the bridge <NUM> of staple <NUM> by the delivery device <NUM> (i.e., the channels <NUM> limit the extent to which bridge <NUM> of staple <NUM> may be stretched).

<FIG> and <FIG> show the staple <NUM> being loaded onto the delivery device <NUM> and the staple <NUM> being strained, i.e., bridge <NUM> being stretched and legs <NUM> being bent so that they are perpendicular to the longitudinal axis of bridge <NUM>. More particularly, <FIG> shows the staple <NUM> loaded onto the staple mount <NUM> of the delivery device <NUM> while the staple mount <NUM> of the delivery device <NUM> is in its closed (i.e., non-staple-straining) position. This is done by positioning the bridge <NUM> of staple <NUM> in the channel <NUM> of the staple mount <NUM>. In this position, the legs <NUM> of the staple <NUM> are in their unbiased, converging position. <FIG> shows the staple <NUM> after the handles <NUM> of the delivery device <NUM> have been moved together, so that the staple mount <NUM> is in its open (i.e., staple-straining) position. This is done by moving handles <NUM> of delivery device <NUM> together, thereby forcing staple-stretching linkages <NUM> of staple mount <NUM> apart, and causing bridge <NUM> of staple <NUM> to be stretched and causing legs <NUM> of staple <NUM> to be positioned substantially perpendicular to the longitudinal axis of bridge <NUM>.

In an embodiment, the delivery device <NUM> is constructed so that upon squeezing the handles <NUM>, the legs <NUM> of the staple <NUM> are first bent to perpendicular and then, when the legs <NUM> of the staple <NUM> are substantially perpendicular, the bridge <NUM> of the staple <NUM> is elongated.

In another embodiment, the staple <NUM> is configured so that the force that is generated as the staple <NUM> reconfigures (i.e., as the bridge <NUM> foreshortens and the legs <NUM> bend inward) is less than the "tear through" force of the bone receiving legs <NUM>, i.e., staple <NUM> is specifically engineered so as to not "tear through" the bone tissue when attempting to reconfigure. The delivery device <NUM> may include the aforementioned locking feature <NUM> which enables the surgeon to control the extent to which the staple <NUM> is strained (e.g., to bend only the legs of the staple, or to both bend the legs of the staple and strain the bridge of the staple, and to control the extent to which the bridge is stretched), thereby allowing the surgeon to tailor the compressive forces and recoverable strain imposed on the anatomy, depending on bone quality. The compressive forces of the staple <NUM> can be controlled by modulating the material properties of the staple and/or the geometry of the staple.

The percentage of cold work in the shape memory material forming the staple <NUM> affects the compressive force generated by the reconfiguring staple <NUM>. As the percentage of cold work increases, the compression force declines. In and embodiment, the staple <NUM> includes between about <NUM>% and <NUM>% cold work to control the recovery force of the staple <NUM>. However, other degrees of cold work may be used, and/or the material may not be cold worked at all.

Another material property that affects the compression force of the staple <NUM> is the temperature differential between the body that the staple <NUM> will be implanted into (assumed to be <NUM>, which is the temperature of a human body) and the austenite finish temperature of the shape memory material forming staple <NUM>. A smaller temperature differential between the two will result in the staple <NUM> generating a smaller compressive load; conversely, a larger temperature differential between the two will result in the staple generating a larger compressive load. The shape memory material that the staple <NUM> is made out of may have an austenite finish temperature of greater than about -<NUM>, resulting in a temperature differential of about <NUM> when the staple <NUM> is implanted (assuming that the staple is implanted in a human body).

The geometry of the staple <NUM> may also affect the compression forces generated. The cross-sectional area of the bridge <NUM> and the cross-sectional area of the legs <NUM> affect the compression forces generated by the reconfiguring staple <NUM>. As the cross-sectional areas increase, so do the compression forces that the reconfiguring staple <NUM> will generate.

The staple legs <NUM> are critical for transmitting the compression force to the bone without "tearing through" the bone. The height, width, and length of the staple legs <NUM>, and the geometry of the staple legs <NUM>, are all significant relative to the staple's ability to not "tear through" the bone. Staple legs <NUM> with greater surface area are better able to distribute the compression force and thus not "tear through" the bone.

<FIG> schematically illustrates how the staple <NUM> may be used to reduce a fracture <NUM> and generate and maintain greater and more uniform compression between bone fragments <NUM> and <NUM> to aid in fracture healing. More particularly, the fracture <NUM> 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 <NUM> the correct distance apart to accommodate the legs <NUM> of the strained staple <NUM>. The staple <NUM> is loaded onto the delivery device <NUM>, and the delivery device <NUM> is used to stretch the bridge <NUM> and straighten the legs <NUM> of staple <NUM> (i.e., by squeezing together handles <NUM>). While still on the delivery device <NUM>, the legs <NUM> of the staple <NUM> are placed into the pre-drilled holes <NUM>. The staple <NUM> is then released from the delivery device <NUM>, which allows the stretched bridge <NUM> of the staple <NUM> to foreshorten so as to apply compression to the fracture <NUM>, and which allows the strained legs <NUM> of the staple <NUM> to "kick in" and thereby apply additional inward pressure across the fracture <NUM>. Thus, the staple <NUM> applies more uniform compression across the fracture site, generating compression across both the cortical and intramedullary surfaces, using the compressive forces generated by the foreshortening bridge <NUM> of the strained staple <NUM> and using the compressive forces generated by the inwardly bending legs <NUM> of the strained staple <NUM>.

Significantly, when the bridge <NUM> and the legs <NUM> of the staple <NUM> generate a compressive force, both the cortical regions of the bone fragments and the cancellous regions of the bone fragments are pulled together. This provides a superior balance of compression across different regions of the bone.

It should also be appreciated that, if desired, the staple <NUM> could be used to attach soft tissue to bone (e.g., to attach a rotator cuff to bone).

It should also be appreciated that the delivery device <NUM> may not always seat the staple <NUM> with the bridge <NUM> of the staple <NUM> seated directly against the cortical surface of the bone (i.e., the bridge <NUM> may sit slightly above the cortical surface of the bone). Therefore, a tamp of the sort well known in the art may be used to fully seat the staple <NUM> bridge against the cortical surface of the bone.

In some circumstances it can be desirable to modify the delivery device <NUM> to ensure that the legs <NUM> do not be bent past <NUM> degrees (relative to the longitudinal axis of bridge <NUM>) when the staple <NUM> is strained. More particularly, in some constructions, the staple <NUM> can require more force to stretch the bridge <NUM> than to bend the legs <NUM>. In this circumstance, there is the possibility that legs <NUM> will be bent to <NUM> degrees (relative to the longitudinal axis of bridge <NUM>) and then, as bridge <NUM> is stretched, legs <NUM> may be bent past <NUM> degrees (relative to the longitudinal axis of bridge <NUM>). Therefore, it can be desirable to provide means for preventing legs <NUM> from being bent past <NUM> degrees (relative to the longitudinal axis of bridge <NUM>).

To this end, and looking now at <FIG>, <FIG>, and <FIG>, a delivery device <NUM> may be constructed so that its staple-straining linkages <NUM> are each formed with an outboard constraint <NUM> that prevents legs <NUM> from being bent past <NUM> degrees (relative to the longitudinal axis of bridge <NUM>) when the staple <NUM> is strained.

In an embodiment, the staple <NUM> and delivery device <NUM> establish a surgical system that is provided in the form of a sterilized kit. The kit may include additional instruments to aid in the implantation of the staple (e.g., k-wire, drill bit, staple size guide, tamp, etc.).

As discussed above, the staple <NUM> is strained so that, upon deployment in the bone, it will provide compression across a fracture. However, it should also be appreciated that, if desired, the staple <NUM> could be configured to provide a distraction force to a bone. In this situation, the staple <NUM> can be configured and strained so that the bridge <NUM> is compressed, and/or legs <NUM> can be bent outward, such that when staple <NUM> is deployed in bone, the reconfiguring staple <NUM> applies a distraction force to the bone to cause the bone to grow and thereby elongate.

As further discussed above, the staple <NUM> is 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 be a metal alloy (e.g., Nitinol) or a polymer (e.g., appropriately processed PEEK). In this respect it should be appreciated that staple <NUM> can be manufactured out of a single piece of shape memory material (i.e., so as to create an integral, monolithic structure), and the different regions of the staple worked differently, in a metallurgical sense, so that different regions of the staple have different mechanical properties and exhibit different mechanical characteristics, even as they form a single, integral, monolithic structure.

In an embodiment, the staple <NUM> can be manufactured so that bridge <NUM> is elastic, the legs <NUM> are elastic, and the curved hinge regions <NUM> are elastic, in which case the bridge <NUM> and the legs <NUM> can both be elastically deformed for providing compression to the fracture site after implantation. The bridge <NUM> and the legs <NUM> may be worked metallurgically so that they have the same or different mechanical properties.

However, in yet another embodiment, the staple <NUM> can be manufactured so that the bridge <NUM> is malleable and non-superelastic (e.g., fully annealed Nitinol, or martensitic Nitinol with an austenite start temperature greater than body temperature), and legs <NUM> and hinge regions <NUM> are superelastic (e.g., austenite but capable of forming stress-induced martensite). This allows the malleable bridge <NUM> of staple <NUM> to be inelastically bent (i.e., to take a set) to accommodate a particular geometry of the cortical anatomy, while still allowing the superelastic legs <NUM> of the staple to generate compression. By way of a non-limiting example, many bones exhibit an hourglass surface profile; moreover, certain orthopedic indications (e.g., an Akin Osteotomy) often results in a cortical surface that is concave when the bones are re-approximated. In these situations, a staple with a straight bridge will not sit flush on the bone surface, which can lead to patient discomfort. In this respect it should also be appreciated that where bridge <NUM> is malleable and legs <NUM> are superelastic, legs <NUM> of the staple <NUM> may be manufactured at a more acute angle (see <FIG>) to allow for adequate fracture compression and reduction in the event that bridge <NUM> must be bent downward (e.g., deformed to a concave position) to meet the anatomical structure of the cortical bone.

<FIG>, for example, shows a monolithic staple <NUM> where bridge <NUM> is malleable and legs <NUM> are superelastic, and where staple <NUM> is shown in its unbent and unstrained condition, and <FIG> shows staple <NUM> where bridge <NUM> has been bent to give it an altered configuration. The staple <NUM> of <FIG> and <FIG> may be formed out of a single piece of shape memory material, whereby to form a single, integral, monolithic structure, with the single piece of shape memory material having different regions of the staple worked differently, in a metallurgical sense, so that different regions of the staple <NUM> have different mechanical properties and exhibit different mechanical characteristics, i.e., bridge <NUM> is malleable and legs <NUM> are superelastic.

It may be desirable for the staple <NUM> to start with a bridge that is convex, e.g., such as the staple <NUM> shown in <FIG>. This allows the bridge <NUM> of the implanted staple <NUM> to sit flush with the cortical bone surface if the bone surface is largely planar. More particularly, if the bridge <NUM> of staple <NUM> were to be linear, and the legs <NUM> strained and the staple <NUM> inserted into a prepared fracture site where the cortical surface is largely planar, the resulting implanted staple <NUM> could have two small "humps" at the outer ends of the bridge, i.e., at the bridge-hinge interface. Starting with a convex-shaped bridge (i.e., such as is shown in <FIG>) largely eliminates these "humps.

Thus, in another embodiment, the staple <NUM> is formed out of a single piece of shape memory material (i.e., so as to form a single, integral, monolithic structure), with the shape memory material being worked so that bridge <NUM> is malleable (e.g., fully annealed Nitinol, or martensitic Nitinol with an austenite start temperature greater than body temperature) and legs <NUM> are superelastic (e.g., austenite but capable of forming stress-induced martensite), such that bridge <NUM> of staple <NUM> may be bent to contour to the surface of the bone while the compressive force generated by the superelastic legs <NUM> of the staple are used to help fuse the bone.

A bending device can be used to bend the bridge <NUM> of the staple <NUM> prior to implantation of the staple <NUM>. An exemplary bending device <NUM> is shown in <FIG>. The bending device <NUM> is essentially a modified plier assembly. The staple <NUM> is placed into the bending fixture <NUM> of bending device <NUM>, and compressing the handles <NUM> causes the bridge <NUM> of the staple <NUM> to be bent to better meet the shape of the cortical bone surface.

More particularly, <FIG> shows a close-up of the bending fixture <NUM> of bending device <NUM>. Two pins <NUM> are used to locate the staple, and a third pin <NUM> is used to bend the bridge <NUM> of the staple <NUM> when the handles <NUM> of bending device <NUM> are compressed. A channel <NUM> in bending fixture <NUM> both directs the shape of the contour while also serving to limit the maximum bend imposed on the bridge <NUM> of the staple <NUM>.

After the bridge of the staple has been bent to the desired geometry (e.g., the geometry shown in <FIG>), the legs <NUM> of the staple <NUM> can be strained open (e.g., to the geometry shown in <FIG>) to allow the bent, strained staple <NUM> to be inserted into the prepared fracture site. In an embodiment, such as shown in <FIG>, the bent staple <NUM> may be strained using a plier assembly <NUM> comprising a pair of handles <NUM> and a straining fixture <NUM>. The previously-bent staple <NUM> is placed into the straining fixture <NUM>, and then compressing the handles <NUM> causes the staple's legs <NUM> to be strained opened to parallel. The plier assembly <NUM> can also be used to insert the staple <NUM> into the bone after the legs <NUM> of the staple <NUM> have been strained open to substantially parallel.

<FIG> and <FIG> show the construction and function of the straining fixture <NUM> of the plier assembly <NUM> in greater detail. The staple <NUM> is supported by two internal pins <NUM> and two external pins <NUM>. Compressing the handles <NUM> causes the staple legs <NUM> to move from an inward-pointing or converging configuration (see <FIG>) to a more open (e.g., parallel) state (see <FIG>). The previously-bent staple <NUM>, with the legs <NUM> now strained to the open state, is then ready for implantation across the fracture line. When implanted in bone and thereafter released from the plier assembly <NUM>, the strained legs <NUM> of staple <NUM> then kick inward, reducing the fracture and generating and maintaining compression across the fracture.

<FIG> and <FIG> illustrate how a staple <NUM> formed out of a shape memory material, with its bridge <NUM> being malleable (e.g., fully annealed Nitinol, or martensitic Nitinol with an austenite start temperature greater than body temperature) and its legs <NUM> being superelastic (e.g., austenite but capable of forming stress-induced martensite), may be used to reduce a fracture <NUM> between two bone fragments <NUM>, <NUM> and generate and maintain compression across the fracture <NUM>. Significantly, because the bridge <NUM> of the staple <NUM> is malleable and the legs <NUM> of the staple <NUM> are superelastic, the bridge <NUM> of the staple <NUM> can be first bent to match the surface profile of the bone while enabling the superelastic legs of the staple to be elastically strained to provide the compressive force across the fracture <NUM>.

In an embodiment, the staple <NUM> is first loaded onto the bending device <NUM> and the bridge <NUM> of the staple <NUM> is bent to accommodate the surface profile of the patient's cortical bone anatomy. The surgeon may use fluoroscopy or trial-and-error to bend the bridge <NUM> of the staple <NUM> to the appropriate configuration. With the bridge <NUM> of the staple <NUM> appropriately bent, a drill guide (not shown) is used to drill holes <NUM> into the bone fragments <NUM>, <NUM> at the appropriate locations on either side of the fracture <NUM> to accommodate the strained staple legs <NUM>. The staple <NUM> is then loaded onto the plier assembly <NUM>, and the superelastic legs <NUM> are then elastically bent to the open state.

With the bridge <NUM> of the staple <NUM> inelastically bent into the appropriate configuration and with the legs <NUM> of the staple <NUM> elastically strained to substantially parallel, the staple <NUM> can be inserted into the pre-drilled holes <NUM> in bone fragments <NUM>, <NUM>. The staple <NUM> is then released from the plier assembly <NUM> and tamped to sit flush with the cortical surface, with the inelastically bent bridge <NUM> of the staple <NUM> more closely matching the surface contour of the bone. The elastically-strained superelastic legs <NUM> of the staple <NUM> apply a compressive force across the fracture <NUM>.

If desired, in embodiments where the staple <NUM> is provided with a malleable bridge <NUM>, the malleable bridge <NUM> may be bent, or further bent, after the staple <NUM> has been deployed in bone, e.g., to match, or to more closely match, the surface profile of the bone.

In other embodiments, the bone may have a convex profile. In such an embodiment, it may be desirable to set the staple <NUM> so that its bridge <NUM> has a convex configuration. To this end, and looking now at <FIG>, there is shown a staple <NUM> which has been inelastically bent to have a convex bridge <NUM> and two legs <NUM>.

<FIG> and <FIG> illustrate another exemplary bending device <NUM> which may be used to bend the bridge <NUM> of a staple <NUM>, e.g., the bridge <NUM> of the staple <NUM> shown in <FIG>. The bending device <NUM> generally includes a housing <NUM> supporting a pair of pins <NUM>. The pins <NUM> receive the staple <NUM> in the manner shown in <FIG>. The bending device <NUM> also includes a screw mechanism <NUM> which selectively advances an element <NUM> toward pins <NUM> or retracts element <NUM> away from the pins <NUM>. As a result of this construction, when the staple <NUM> is mounted on the pins <NUM>, the screw mechanism <NUM> can be used to drive element <NUM> against the bridge <NUM> of the staple <NUM> to bend the bridge <NUM>.

If desired, the staple <NUM> could be used to attach soft tissue to bone (e.g., to attach a rotator cuff to bone). It should be appreciated that the delivery device <NUM> discussed above may not always seat the staple <NUM> with the bridge <NUM> of the staple <NUM> seated directly against the cortical surface of the bone (i.e., the bridge of the staple may sit slightly above the cortical surface of the bone). Therefore, a tamp of the sort well known in the art may be used to fully seat the staple bridge <NUM> against the cortical surface of the bone.

In another embodiment, the staple <NUM>, the bending device <NUM> and/or the bending device <NUM>, and the delivery device (i.e., plier assembly) <NUM> are provided as a system in the form of a sterilized kit. The kit may include additional instruments to aid in the implantation of the staple (e.g., k-wire, drill bit, staple size guide, tamp, etc.).

<FIG> illustrate a combination bending device and delivery device <NUM>. Combination device <NUM> has plier legs <NUM>, <NUM> which connect to links <NUM>. Plier legs <NUM>, <NUM> and links <NUM> are connected with threaded bosses <NUM> and <NUM>. Threaded bosses <NUM> and <NUM> are coupled by a threaded rod <NUM>. The threaded rod <NUM> has a handle <NUM>. Turning the handle <NUM> clockwise causes the plier legs <NUM>, <NUM> to become more parallel to each other (see, e.g., <FIG>).

Referring to <FIG>, the back side of the combination bending device and delivery device <NUM> is shown. A staple holder <NUM> is attached to plier leg <NUM> and a bending anvil <NUM> extends from the plier leg <NUM>. When the staple <NUM> is placed onto the staple holder <NUM> and the anvil <NUM> is pressed against the staple <NUM> by turning the screw <NUM> clockwise, the anvil <NUM> bends the bridge <NUM> of the staple <NUM> (see, e.g., <FIG> and <FIG>).

After the staple <NUM> has had the bridge <NUM> bent, the staple <NUM> can be prepared for implantation. The ends of the plier legs <NUM> and <NUM> have staple grips <NUM> which engage the hinge region of the staple <NUM> (see, e.g., <FIG>). When the plier legs <NUM> and <NUM> are moved to a parallel position, the legs <NUM> of the staple <NUM> become more parallel. With the staple <NUM> mounted to the legs <NUM>, <NUM> of the combination bending device and delivery device <NUM>, the combination device <NUM> is used to insert the staple <NUM>. The surgeon can gradually release the staple <NUM> from the combination device <NUM> by articulating the legs <NUM>, <NUM> away from the parallel position.

Conventional shape memory staples typically generate between about 20N and about 120N of compressive force from the staple legs kicking inward. The staples of the present disclosure which include a stretched bridge generate a compressive load of greater than the 20N to 120N generated by other like-sized conventional staples, thereby providing significantly increased compressive forces without tearing through or otherwise damaging the bone. Additionally, the compressive force provided by the stretched bridge staples of the present disclosure are more uniformly distributed across the fracture line (i.e., across the cortical bone and the cancellous bone).

An additional exemplary surgical system is illustrated with respect to <FIG>. The surgical system includes a delivery device <NUM> and a staple <NUM>. The delivery device <NUM> can be used for implanting staples <NUM> that do not have holes in their hinge regions. Such a staple <NUM> is shown attached to the delivery device <NUM> in <FIG>. In an embodiment, and referring to both <FIG> and <FIG>, the delivery device <NUM> may engage the staple <NUM> underneath a staple bridge <NUM> and more specifically underneath a hinge location <NUM>.

Referring to <FIG>, rotating a knob <NUM> of the delivery device <NUM> causes a plunger <NUM> to deform the staple bridge <NUM>. In the deformed state, as is shown in <FIG>, the staple legs <NUM> and <NUM> are parallel to each other for insertion into prepared bone holes. Turning the knob <NUM> counterclockwise releases the strain on the staple bridge <NUM> and allows the staple <NUM> to re-assume a convergent position.

Referring now to <FIG>, the delivery device <NUM> may also be used to implant staples <NUM> that have holes <NUM> in the hinge region. The delivery device <NUM> does not have to engage the staple <NUM> in the holes, however. Instead, the delivery device <NUM> can engage the staple <NUM> under the bridge <NUM>.

As shown in <FIG>, the delivery device <NUM> can be used to cause staple bridge <NUM> to take a permanent set. The staple bridge <NUM> may be first heat treated to be fully annealed and or martensitic at body temperature. Turning the knob <NUM> of the delivery device <NUM> causes the plunger <NUM> to permanently deform the staple bridge <NUM> to a concave state (see, e.g., <FIG>). This causes staple legs <NUM> and <NUM> to become parallel. It should be appreciated that releasing the strain on staple bridge <NUM> after the legs <NUM>, <NUM> are in the parallel position will cause staple legs <NUM> and <NUM> to assume a convergent position.

<FIG> illustrate another exemplary surgical system including a delivery device <NUM> and a staple <NUM>. The delivery device <NUM> can be used for implanting staples <NUM> that do not have holes in their hinge regions <NUM>. In an embodiment, the delivery device <NUM> engages the staple <NUM> underneath a staple bridge <NUM> and more specifically underneath each hinge region <NUM>. The delivery device <NUM> may include pivot pins <NUM> that engage underneath the staple bridge <NUM>. The pivot pins <NUM> are connected to pivot arms <NUM> that are pivotable relative to a body <NUM> of the delivery device <NUM>.

Rotating a knob <NUM> (see <FIG>) of the delivery device <NUM> causes a plunger <NUM> to deform the bridge <NUM> of the staple <NUM>. In an embodiment, the plunger <NUM> includes a channel <NUM> sized to receive the bridge <NUM>. In the deformed state, legs <NUM> of the staple <NUM> move toward a parallel position relative to one another for insertion into prepared bone holes. Turning the knob <NUM> counterclockwise releases the strain on the bridge <NUM> and allows the staple <NUM> to move back toward a convergent position.

Yet another surgical system is illustrated with respect to <FIG>. In this embodiment, the surgical system is a compression screw system for generating and applying compression within a body.

<FIG> illustrate a compression screw <NUM> for bringing bones into close proximity with each other, generating a compressive load, and maintaining that compressive load for a prolonged period of time while the bone fuses. The compression screw <NUM> generally includes an enlarged proximal head <NUM>, a reversibly axially strainable central region <NUM>, and a distal threaded region <NUM>. The compression screw <NUM> contains a central lumen <NUM> that extends the length of the compression screw <NUM> and a wider intermediate counterbore <NUM>. The enlarged head <NUM> has an internally threaded region <NUM> for mating with an internal retaining pin.

<FIG> schematically illustrates how the central region <NUM> of the compression screw <NUM> can be reversibly stretched. When the compression screw <NUM> is made from Nitinol, for example, that stretch can be up to <NUM>%.

Referring to <FIG>, the surgical system includes a compression screw <NUM> and internal retaining pin <NUM>. The internal retaining pin <NUM> comprises a tube <NUM> that is sized to slide into the intermediate counterbore <NUM> and a proximal threaded region <NUM> that mates with screw internal threaded region <NUM>. When the screw <NUM> is stretched and the internal retaining pin <NUM> is inserted into the compression screw <NUM>, the internal retaining pin <NUM> maintains the screw <NUM> in the elongated state. Removal of the internal retaining pin <NUM> allows the screw <NUM> to return to its original unstrained state.

<FIG> illustrate additional components of the surgical system. In an embodiment, the surgical system includes a washer <NUM>. The washer <NUM> is sized to allow the distal threads <NUM> of the compression screw <NUM> to pass through the washer <NUM> but not allow enlarged head <NUM> to pass through. The washer <NUM> may have textured surface <NUM> on its distal face to better engage bone. The textured surface <NUM> may include spikes, in an embodiment. The washer <NUM> is designed to distribute the compressive load over a larger surface area. The washer <NUM> is contoured to allow the enlarged head <NUM> to articulate in the washer <NUM>. This allows the screw <NUM> to be inserted at an angle (see, e.g., <FIG>), and still have the washer <NUM> maximize its surface contact with the bone.

<FIG> shows the compression screw <NUM> and washer <NUM> being used to fuse two adjacent vertebra <NUM> and <NUM>, such during a spinal fusion procedure.

Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.

Claim 1:
A surgical system, comprising:
a delivery device (<NUM>, <NUM>) including pins (<NUM>), a rotatable knob (<NUM>, <NUM>) and a plunger (<NUM>, <NUM>); and
a staple (<NUM>, <NUM>, <NUM>) mountable to the delivery device, the staple (<NUM>, <NUM>, <NUM>) made of a shape memory material and including a bridge (<NUM>, <NUM>, <NUM>), a first leg (<NUM>, <NUM>, <NUM>, <NUM>) connected to the bridge (<NUM>, <NUM>, <NUM>) by a first hinge region (<NUM>, <NUM>, <NUM>), and a second leg (<NUM>, <NUM>, <NUM>, <NUM>) connected to the bridge (<NUM>, <NUM>, <NUM>) by a second hinge region (<NUM>, <NUM>, <NUM>),
characterized in, that
the pins (<NUM>) engage the staple (<NUM>, <NUM>, <NUM>) under the bridge (<NUM>, <NUM>, <NUM>) such that rotation of the rotatable knob (<NUM>, <NUM>) is configured to move the plunger (<NUM>, <NUM>) and deform the bridge (<NUM>, <NUM>, <NUM>), such that the staple (<NUM>, <NUM>, <NUM>) moves from a first position in which the bridge is convex and the first leg and the second leg (<NUM>, <NUM>,<NUM>, <NUM>) are convergent to a second position in which the bridge is concave and the first leg and the second leg (<NUM>, <NUM>,<NUM>, <NUM>) are substantially parallel.