FIELD OF INVENTION

The present invention relates to a medical device for approximation, alignment, distraction, fixation, or compression of opposing regions along a tissue plane. In particular, the device relates to a medical device that is manufactured in a first at-rest shape and state, that is deformed prior to placement on a tissue plane in a patient, and that reverts back toward the at rest shape upon placement, thereby providing tissue-shaping forces across a treatment area.

BACKGROUND

Many kinds of medical treatments incorporate devices that hold parts of the body in a particular configuration for healing. For example, cuts, wounds, and surgical incisions benefit from being held together in a fixed arrangement to promote efficient healing and to minimize scarring. Throughout the centuries many mechanisms have been created to align opposing tissue planes. Other devices include adhesives, clamps, screws, rods, staples, tapes, cord-like elements (sutures, ligature), or other mechanisms. Each of these approaches has a range of different qualities that may include flexibility versus rigidity, loose alignment versus compression, inversion versus eversion of a plane, external versus internal application, and permanent versus temporary application of devices. Many of these approaches require that the opposing elements be aligned prior to fixation (e.g. tapes, adhesives) while in other instances the elements are aligned as the fixation is applied (e.g. sutures, staples).

A wide variety of strategies and mechanisms have been employed to affect and control relationships between tissue planes and thus promote desired therapeutic effects. For example, U.S. Pat. No. 4,702,251 (Sheehan 1987) illustrates the use of a bandage that adheres to a patient's skin and forms a bridge over a tissue plane to align and evert the skin. United States Patent Publication No. 20090240186 (Fang) discloses a bandaging device that includes sections attached to either side of a wound and a lifting portion that is grasped to pull the wound sections together. See also, U.S. Pat. No. 815,264 (Chambers 1906) (disclosing a suture bridge); U.S. Pat. No. 2,371,978 (Perham 1941) (disclosing a clamp for retaining the edges of a wound); and U.S. Pat. No. 3,487,836 (Niebel 1968) (disclosing a surgical strip stitch). The lifting portion includes sections of the bandage that adhere to one another to apply approximating forces onto opposite sections of a wound.

The repair of a surgical or traumatic wound by the approximation of the wound margins is a prototypical example, and in this action the tissue planes need to be brought into alignment with the appropriate degree of tension to promote wound healing without adversely affecting tissue perfusion. Eversion of the wound margins, such as in closure of skin wounds, supports wound healing, the approximation of the deeper subcutaneous tissue margins, and an optimal scar appearance. Advancement of tissues to close tissue defects, compression of tissues to promote healing (e.g. treatment of fractures or reduction in hypertrophic scars and keloid scars), and distraction or expansion of tissues to alter tissue dimensions are all additional examples of actions where the relationships between tissue planes and the forces acting upon them need to be controlled.

Heretofore many devices and mechanisms have been utilized toward these goals, and the device or mechanism selected can differ significantly in order to address the specific clinical situation, the characteristics of the tissues being treated, and other factors. Surgical needles and sutures, surgical staples, adhesives, tapes, rigid plates and screws, rods, clips, tissues expanders, and distracters are all examples of the variety of devices and mechanisms that can be employed to position and control tissues for therapeutic purposes. With any given tissue type and clinical situation more than one of these options may be considered, each having advantages and disadvantages. In a given situation factors that may represent advantages are ease of application, stability or security of approximation, adjustability, point-to-point approximation, and an a-traumatic device-tissue interface. Similarly, factors that may represent disadvantages are increased cost and complexity, the persistence of device elements (foreign body) within the wound bed that could adversely affect healing or the risk of infection, the necessity of device removal, and pain upon application or removal with a subsequent requirement for anesthesia. Other characteristics of the wound treatment or closure mechanisms can affect the healing of the wound or the appearance of the scar, such as the relative elasticity of the closure to allow responses to mechanical forces, the inflammatory reaction that may be generated by hydrolysis of absorbable closure materials, and the pressure points or tissue perforation points that create new points of scaring outside of the immediate tissue healing zone.

In addition to the need to control the orientation and alignment of tissues, the mechanical environment of the tissues significantly affects healing. Increased tension across a healing wound not only leads to an increase in the risk of wound dehiscense in the acute treatment period, but also significantly affects the wound healing process chronically, leading to increased scaring and an increased risk of hypertrophic scars and keloids. Factors which increase wound tension tend to have poorer scaring characteristics, examples of which include the presence of chronic swelling, gravitational forces (e.g. a sternal wound location which is impacted by the weight of the breasts) or mechanical forces (e.g. over the extensor surface of a joint where normal joint motion may increase the tension on the skin). Incisional closures, where no tissue is removed and subsequently tension is less, tend to have better scaring characteristics than excisional procedures, wherein removal of tissues increased the subsequent wound closure tension. Increased wound tension has been demonstrated to lead to an increased number of fibroblasts, increased collagen deposition, alterations in the orientation of fibroblasts, and changes in the level of certain bio-chemicals, among other effects. Reducing the tension on healing wounds by mechanical means is an accepted strategy to assist healing and scar appearance. In addition to the reduction of tension, in some circumstances a compressive mechanical environment is utilized in treatment, such as in the treatment of established hypertrophic scars and keloids or in the treatment of osseous wounds (bone fractures or osteotomies).

Along these lines, one example of a device that is used to direct planned forces onto a tissue plane is set forth in published United States Patent Publication No. 20120035521 (Zepeda 2012). The Zepeda application discloses a kit that includes a bandage applicator that applies a predetermined strain across a bandage placed onto a patient's injured skin. The engineered strain in the bandage is applied to the skin after attaching the bandage to the skin and removing the bandage applicator. The bandage applicator has numerous parts and connectors that must be configured prior to use and increase the complexity of the device.

In the art of medical devices used for tissue treatment, there continues to exist a need for a medical device that is capable of applying a particularly directed force vector across a tissue plane without the need for cumbersome and costly connected pieces and parts within the device.

SUMMARY

Accordingly, there is provided a medical device for approximation, alignment distraction, fixation, stabilization, or compression of opposing members comprising: a central section capable of compression and decompression; lateral sections on each side of the central section; and areas on the device for attaching the device directly to a patient's tissue. The device has a pre-defined shape and state when at rest and is capable of distortion or deformation to load particularly engineered potential force into the device for application to a tissue plane. In one embodiment, the deformation is accomplished by distorting the shape of the device and adjusting the distance between opposite sides of the central section or the distance between the lateral sections that attach to a patient. Upon application to the patient, the potential forces in the device are released as the device reverts back toward its original at-rest state. The connection between the device and the tissue plane resists the device's natural tendency to revert to an at-rest position and yields a desired resultant force along the tissue plane. Depending upon the direction and magnitude of the potential forces loaded into the device by deformation, the resultant forces on the tissue plane move sections of the tissue plane to desired positions for more efficient healing and/or less scarring.

Loading potential forces into the device may be accomplished by squeezing or compressing sides of the device together before applying the device to a tissue plane. As the device tends to open back up to return to an at-rest state, the device provides a distracting or opening force across a treatment area. Alternatively, the device may be stretched or opened from side to side so that, upon application to a tissue plane, the device provides a closing or approximating force across a treatment area. The size and magnitude of the resultant forces on a tissue plane are pre-planned by applying appropriate deformation forces to the medical device prior to attaching the device over a treatment area.

In one embodiment, the medical device is a tissue bridge that connects to a tissue plane along attachment zones on an underside of the device. The device includes a central section that connects to opposite lateral sections, and the underside of each lateral section includes a respective attachment zone for direct placement on a tissue plane such as a patient's skin or other anatomic structure. The central section is designed to extend over a treatment area. Transitional sections, or shoulders, extend from the central section to the lateral sections to provide a continuous structure that may be formed in a single piece construction. The shape of the central, transitional, and lateral sections may be customized to provide a desired resultant force across a treatment area.

The tissue bridge may be deformed to load potential forces into the structure prior to placing the tissue bridge onto a tissue plane. The deformation may be accomplished manually, mechanically, or with the assistance of a tissue bridge applicator. The applicator provides a convenient tool for engaging the tissue bridge, providing a deformational force to load the tissue bridge with potential energy, applying the tissue bridge to a tissue plane, and then separating from the tissue bridge as necessary or desired.

In yet another embodiment of the invention, the tissue bridge may incorporate a two-piece construction in which a tissue bridge connects to an elastomeric strip that adheres to a patient (e.g., a bandage). By deforming the tissue bridge and loading potential force therein, the two piece construction also stretches or deforms the elastomeric strip for placing on a tissue plane across a treatment area. In this way, the elastomeric strip and the tissue bridge provide medical intervention across the tissue plane. In this embodiment, the tissue bridge may be held in place with the elastomeric strip or removed to reduce resultant force across the tissue plane.

The two piece embodiment may be configured as a combination of a tissue bridge and a bandage. The tissue bridge may have an arcuate shape or may be a flat body adhering to the bandage. In one configuration, the tissue bridge and the elastomeric bandage are both flat so that neither the bridge nor the bandage are under any tension in an at-rest state and are conducive to folding without deforming either component. Generally known adhesives of varying strength may be used to attach the bandage to the tissue plane and to attach the tissue bridge to the bandage. The connection between the tissue bridge and the bandage may allow for the tissue bridge to be peeled off the bandage after the bandage is applied to a treatment area.

The tissue bridges disclosed herein are useful as stand-alone devices or used in combination with one another. In another embodiment, a plurality of tissue bridges may be arranged across a tissue plane to provide scaffolding for placing layered materials (e.g., bandages, adhesive sheets, medicinal sheets) over the series of tissue bridges. For embodiments in which the tissue bridges include raised portions over a treatment area, the series of tissue bridges may support an adhesive sheet so that the tissue bridges and the overriding sheet form a conduit with a space defined between the treatment area and the sheet. This space may be used for additional medical intervention as described below (i.e. drainage, irrigation, inspection, application of medicines and anesthesia).

Overall, the devices disclosed herein function for force transmission and modulation across a bridge or conduit between tissue planes acting through zones of attachment. The tissue bridge can assume a wide variety of designs dependent upon the characteristics of the tissues being treated, the method of attachment to the tissue planes, the geometric configuration of the device, the direction and magnitude of the forces required, the component material(s) or tissue(s) properties, aesthetics, secondary attachment requirements or other factors. In order to generate different summary force vectors, effective attachments and geometric configurations required for different clinical situations, each these characteristics can be modified independently or in any combination thus producing a spectrum of configurations, embodiments, and effects, and the vast array of such variations are obvious to ones skilled in the art.

The tissue bridge disclosed and claimed herein exerts its effect through a “pre-loading” or “pre-tensioning” process whereby the bridge and/or the tissue planes being addressed are subjected to a deformational force that is applied prior to the time of device fixation and that is released after partial or total fixation of the device to the tissue planes. Upon release of this deformational force the potential forces thus generated within the device and/or tissues are released to act upon the tissue planes until such time that the device is removed, absorbed, released, detached, or tissue characteristics change such that the device is brought into a non-tensioned configuration.

The resultant vectors applied to the tissue planes are a function of the rotational stiffness of the device (k=M/Ø) as a function of the device dimensions, geometry, and the elastic modulus of the construction materials; the method, amplitude, direction and positioning of the pre-leading force applied prior to application; the points and method of fixation to the tissue planes; and mechanical tissue characteristics. The deformational force can be applied to the bridge or to the tissues, or can be applied to both the bridge and the tissues. When the deformational “pre-loading” or “pre-tensioning” force is applied to a tissue bridge, it is applied in a manner such that the force does not exceed the yield point of the device, and upon tissue plane attachment and release of the deformational force the potential energy thus transferred to the bridge can exert its effect on the tissues. When a force is applied directly to the tissues, external mechanical forces are applied to the tissues to control their position and force environment in relationship to the bridge prior to the time of attachment. When the force is applied only to the tissues, the bridge may be either of a non-elastic or elastic construction.

In addition to controlling the forces and spatial relationships between the tissues upon release (static control or static shielding), the bridge also functions to control the mechanical forces to which the tissues may be subjected after application (dynamic control or dynamic shielding). For instance, if there is tissue swelling centrally near the junction where the planes are brought into proximity by the bridge, the elastic nature of the bridge allows this increased pressure to be relieved by undergoing a compensatory distortion in proportion to the force generated within the tissues, thus relieving the tissue tension. If the tissues are subjected to a laterally directed force vector, i.e. when there is a distracting force such as with lateral tissue swelling or resulting from movement in the tissue planes, the bridge can also distort in relation to the applied force vectors, thus absorbing the force and shielding the junction area from said forces. If a centrally directed force vector, i.e. a compressing force, is applied from either one or both sides of the tissue plane junction, the bridge can undergo a centrally directed distortion, with the absorption of the external compression proportional to the distortional force applied. In this way the bridge provides both dynamic response to changes in tissue forces and a dynamic shielding of the zone near the intersection between the tissue planes as well as static tension control and shielding when the mechanical environment is not in flux.

If the bridge is of a rigid design, any asymmetric forces lateral to the bridge can be transmitted to the opposite side, and likewise the zone near the intersection between the tissue planes is shielded. When the bridge has some degree of elasticity and a lateral tissue force vector is applied in an asymmetric manner, the dispersion of forces will be a combination of deformation force absorption within the bridge as well as transmission of the forces through the structure of the bridge to the tissue(s) on the opposite side. In these manners the device functions as a force conduit.

The bridge has a central section or sections, or body(ies), and lateral sections, or limbs which are connected at a transition zone. Each of these sections can be of different dimensions, appearances, curves, angles, or appearance as dictated by specific clinical needs and tissue characteristics. The device is non-linear such that the central section is not in the same plane as the lateral sections, and may rest above a line drawn between the lateral segments, to the side of a line drawn between the lateral segments, or at other angles in relationship to the surface of the affixed tissue planes. The device may or may not demonstrate bilateral symmetry. Within a given device the lateral segments may be identical design or variable design, and the lateral sections can vary in number, orientation, dimension, materials, construction, or method of fixation.

In one embodiment, the central section demonstrates an outward curve, and the transition zone demonstrates an opposite, inward curve. By making the height of the apex of the central section above the attachment surfaces greater, the arch of rotation of the device with deformational force is lengthened. By making the central section thicker or wider, or modifying it with ridges or other supplementary supports, the relative rotational stiffness of the central section is increased which will modify the magnitude of the deformational force required to generate the same degree of central section deformation upon preloading. Other points of relative strength and weakness may be so configured as to create areas of deformation and areas that are not subject to deformation. Multiple curves or angles may be incorporated into the central section, and holes, slots, grooves, ridges, depressions, or other features can be used to provide secondary functions, such as suspension of tissues, interaction with an applicator device, or to facilitate supplemental fixation, such as sutures or staples.

Like the central section, the transition zone and lateral sections can be of virtually infinite shape, feature, and surface characteristics, and modifying these features affects the force transmission and functioning of the device. For example, the shoulder can be configured to be straight (i.e. in alignment with the lateral segment) and simultaneously relatively thin and therefore more flexible, it may produce the shape and function of a transition curve between the central and lateral segments. Similarly, the lateral segments can be made thicker close to the transition curve, thus providing effective force transmission, but thinner away from the transition curve, thus facilitating attachment of the device. The lateral section can demonstrate slots, grooves, notches, holes, pins, hooks, or other features that facilitate attachment both to the tissue planes and for secondary functions. The lateral section can also contain extensions, such as attached meshes, tapes, adhesive strips, struts, or other features that can facilitate in attachment or function.

The lateral sections can attach to the central section in a variety of configurations so as to produce the desired shape both in the pre-loading, loaded (distorted), and applied situations. By modifying the location and zone of attachment the application and method of use can be altered in a wide variety of ways. For example, if the zone of attachment is at the midpoint of the length of the lateral section, the distorting force can be so applied that both a flattening of the central section as well as an increased angulation of the transition point between the central segment and the lateral section can be produced. This increases the distance between the medial heads of the lateral segment in the pre-application configuration, so that when the device is applied, the medial heads of the lateral segments contact the tissue planes first, then as the transition angle is resumed upon release of the distortion force, the attached tissues are advanced medially and the remainder of the lateral section can then be attached. This central advancement can either create a desired tension reduction upon the tissues in the centrally located zone, or if a greater advancement is created then an actual compressive force can be applied. In an alternate embodiment, if the transition point between the central and lateral segments is near the lateral terminus of the lateral segment, then this creates a longer arc of rotation. Altering the relative elasticity or rigidity of the transition zone, the angle or curve at which it is attached, the resultant angle between the central segment and the lateral segment, or any combination of these can alter the resulting forces generated upon application and the responses to changes in the mechanical tissue environment. For example, if the zone of transition between the central and lateral segments is made very flexible or articulated, and the lateral section is adhered to the tissue planes, a lateralizing force will not affect the relative eversion or inversion of the lateral limb, as with its attachment being flexible it will simply passively follow the direction changes of the lateral tissue planes. All of the lateralizing tissue tension force will be transmitted to the central segment. Alternatively, if the zone of transition between the central and lateral segments is made relatively rigid, both the central and lateral sections as well as the transition zone will all undergo a deformational force absorption change.

Other configurations or structural features can be similarly conceived so as to change the response of the device to deformational loading, tissue force interactions, and post-application mechanical force changes. These include, but are not limited to, articulations, joints, pivot points, dimension changes, curves, angles, bends, twists, points of relative strength or weakness, structural reinforcements, points of applicator attachment, or other design elements.

