Flexible plate fixation of bone fractures

0001Cross-reference of related applications This application claims priority to US Patent Provisional Application No. 62/029168, entitled "Flexible Plate Fixation of Fractures," filed July 25, 2014. The aforementioned disclosure is incorporated herein by reference in its entirety.

0002Embodiments herein relate generally to devices for the fixation of fractured bone. Specifically, the present disclosure relates to a bone plate that provides elastic fixation of a fracture. Such elastic fixation allows some movement at the site of the fracture and promotes natural fracture healing by the formation of callus of the fracture.

0003Osteosynthesis plates for fracture stabilization are typically applied using bone screws. Traditionally, bone screws press the plate against the bone surface to provide stable fixation. Recently, lock plates have typically been introduced that have threaded receiving holes for secure, angle-stable fixation of lock screws with corresponding threaded screw heads. These lock plate constructs can provide more durable fixation than traditional non-locking constructs, especially in weak osteoporotic bone.

0004However, the inherent rigidity of the lock plate construct poses two clinical challenges. First, it can alter the load distribution in the bone, which can lead to bone resorption in the load shielding region adjacent to the plate, or fractures due to implant-induced stress concentrations. Second, the high stiffness of the osteosynthesis plate construct suppresses the relative displacement between the bone fragments, but such movement between the bone fragments promotes a natural cascade of fracture healing due to callus formation. Is important for. Therefore, an overly stiff lock plate construct can delay or impede fracture healing, leading to implant breakage or lack of screw fixation in the bone.

0005To better illustrate the bone plates disclosed herein, a list of non-limiting examples is provided here.

0006In Example 1, an apparatus can be provided that includes a bone plate having an upper surface and a bone-facing surface. The bone plate comprises one or more openings extending through the bone plate from the upper surface to the facing surface of the bone. The device can further include one or more sliding elements, each sliding element including a fastener receiving hole, and one or more openings at least partially on one periphery of the receiving hole. Surrounding and one or more openings are at least partially filled with an elastomer to support the elastic suspension of one or more sliding elements in the bone plate. Allows relative displacement between multiple sliding elements and the bone plate. The device can further include at least one sensor that can operate to evaluate one dynamic parameter of one or more sliding elements within the bone plate.

0007In Example 2, the device of Example 1 is optionally configured to be capable of operating the sensor to track the relative position of the sliding element with respect to the bone plate.

0008In Example 3, the device of any one or combination of Examples 1-2 is optionally configured to allow the sensor to operate to measure the displacement of the sliding element with respect to the bone plate. ..

0009In Example 4, the device of any one or combination of Examples 1-3 can optionally operate to measure the pressure in the elastomer in which the sensor suspends the sliding element on the bone plate. Is configured to be.

0010In Example 5, the device of any one or combination of Examples 1 to 4 is optionally configured such that the sensor is at least partially positioned within the elastomer.

0011In Example 6, the device of any one or combination of Examples 1-5 optionally applies pressure to the bone plate by an elastomer suspending a sliding element in the bone plate by a sensor. It is configured to be operational to measure.

0012In the seventh embodiment, the device of any one or a combination of the first to sixth embodiments is optionally configured such that the sensor is self-powered.

0013In the eighth embodiment, the device of any one or a combination of the first to sixth embodiments is optionally configured such that the sensor is powered by an external power source.

0014In Example 9, a plate body having an upper surface and a bone facing surface, a plurality of openings extending from the upper surface to the bone facing surface through the plate body, and one or more sliding elements each including a fastener receiving hole. Each of the sliding elements, one or more, is arranged in one with a different opening such that the opening surrounds the perimeter of the receiving hole at least partially. An elastomer layer that allows the relative displacement of the sliding elements within the plate body by at least partially surrounding each of the sliding elements and the dynamic parameters of one or more sliding elements within the plate body. A bone plate can be provided that includes one or more sensors that can be operated for evaluation.

0015In Example 10, the bone plate of Example 9 is optionally configured such that each receiving hole is a threaded receiving hole.

0016In Example 11, the bone plate of any one or combination of Examples 9 to 10 is optionally configured such that each receiving hole has a cylindrical shape.

0017In Example 12, the bone plate of any one or combination of Examples 9-11 is optionally configured such that the elastomeric layer has a modulus in the range of 0.1-50 MPa.

0018In Example 13, the bone plate of any one or combination of Examples 9-12 is optionally configured such that the elastomer layer is silicon.

0019In Example 14, the bone plate of any one or combination of Examples 9-13 is optionally a sensor and plate as a means for one or more sensors to estimate the progression of fracture healing. It is configured to be operational to measure displacement, pressure, or load to capture the presence or magnitude of load transfer to and from the body.

0020In Example 15, the bone plate of any one or combination of Examples 9-14 is optionally energized by at least one elastomer layer to provide transient power to one or more sensors. It is configured to include the generating element.

0021In Example 16, the bone plate of any one or combination of Examples 9-14 is optionally configured such that one or more sensors are powered by an external power source.

0022In Example 17, the bone plate of any one or combination of Examples 9-16 is optionally one or more to measure the acceleration of the plate body or one or more sliding elements. It is configured to include an accelerometer.

0023In Example 18, the bone plate of Example 17 optionally has a first accelerometer operably coupled to the plate body and a second accelerometer operably coupled to one of the sliding elements. It is configured to include.

0024In Example 19, the bone plate of Example 18 is optionally configured such that the first and second accelerometers provide feedback to determine the relative acceleration of the sliding element with respect to the plate body.

0025In Example 20, a device comprising a bone plate having an upper surface and a bone facing surface is provided. The bone plate comprises one or more openings extending through the bone plate from the upper surface to the facing surface of the bone. The device may further include one or more sliding elements, each sliding element including a fastener receiving hole. One or more openings shall at least partially surround one perimeter of the receiving hole, and one or more openings shall support the elastic suspension of one or more sliding elements in the bone plate. Is at least partially filled with elastomer to allow relative displacement between one or more sliding elements and the bone plate. The device also measures at least one of displacement, pressure, or load to capture the presence or magnitude of load transfer between the sensor and the bone plate and to estimate the progression of fracture healing. Can be equipped with at least one sensor capable of operating.

0026In Example 21, the device or bone plate of any one or combination of Examples 1-20 is optionally configured to use or select all the described elements or options.

0027The embodiments can be easily understood by the following detailed description along with the accompanying drawings and the claims. Embodiments are illustrated in the accompanying drawings as an example rather than a limitation.

0028<figref num="1">It is a top view of the bone plate according to various embodiments.</figref><figref num="2">FIG. 5 is a cross-sectional view of a sliding element having a cylindrical threaded portion according to various embodiments.</figref><figref num="3">FIG. 5 is a cross-sectional view of a bone plate attached to a cylindrical bone member using a bone screw according to various embodiments.</figref><figref num="4">FIG. 3 is a cross-sectional view of a sliding element having a conical threaded portion according to various embodiments.</figref><figref num="5">It is a bottom view of the sliding element and the spring element inside the bone plate which shows except the bottom for visualizing the sliding element according to various embodiments.</figref><figref num="6">It is a bottom view of the sliding element and the integrated spring element inside the bone plate shown except for the bottom to visualize the sliding element according to various embodiments.</figref><figref num="7">It is a bottom view of the sliding element and the integrated spring element inside the bone plate shown except for the bottom to visualize the sliding element according to various embodiments.</figref><figref num="8">FIG. 5 is a cross-sectional view of a sliding element shown in association with a bone screw attached to a cylindrical bone compartment according to various embodiments.</figref><figref num="9">FIG. 5 is a cross-sectional view of a bone plate shown in association with a bone screw attached to two corresponding compartments of cylindrical bone, according to various embodiments.</figref><figref num="10">FIG. 5 is a cross-sectional view of a bone plate attached to a cylindrical bone compartment using a non-collinear lock peg according to various embodiments.</figref><figref num="11">FIG. 5 is a cross-sectional view of a sliding element having a bone plate and a cylindrical threaded portion and an elastomer that suspends the sliding element inside the bone plate according to various embodiments.</figref><figref num="12">FIG. 3 is a bottom view of the sliding elements and elastomers in the slots on the sides of the bone plate shown except for the bottom to visualize the sliding elements according to various embodiments.</figref><figref num="13">It is a top view of the bone plate according to various embodiments.</figref><figref num="14">FIG. 5 is a cross-sectional view of a sliding element having a cylindrical threaded portion according to various embodiments.</figref><figref num="15">FIG. 5 is a diagram of a "smart" bone plate capable of measuring one or more parameters after implantation.</figref><figref num="16A-16B">It is a figure related to the first biomechanics research.</figref><figref num="17A">It is a figure related to the first biomechanics research.</figref><figref num="17B">It is a figure related to the first biomechanics research.</figref><figref num="17C">It is a figure related to the first biomechanics research.</figref><figref num="18A">It is a graph related to the first biomechanics research.</figref><figref num="18B">It is a graph related to the first biomechanics research.</figref><figref num="19A">It is a graph related to the first biomechanics research.</figref><figref num="19B">It is a graph related to the first biomechanics research.</figref><figref num="20A">It is a graph related to the first biomechanics research.</figref><figref num="20B">It is a graph related to the first biomechanics research.</figref><figref num="21A">It is a figure related to the second biomechanics research.</figref><figref num="21B">It is a figure related to the second biomechanics research.</figref><figref num="22A">It is a figure related to the second biomechanics research.</figref><figref num="22B">It is a figure related to the second biomechanics research.</figref><figref num="22C">It is a figure related to the second biomechanics research.</figref><figref num="23A">It is a graph related to the second biomechanics research.</figref><figref num="23B">It is a graph related to the second biomechanics research.</figref><figref num="24A">It is a graph related to the second biomechanics research.</figref><figref num="24B">It is a graph related to the second biomechanics research.</figref><figref num="24C">It is a graph related to the second biomechanics research.</figref><figref num="25A-25C">It is a figure and a graph related to the second biomechanics research.</figref><figref num="26A-26C">It is a figure and a graph related to the second biomechanics research.</figref>

0029In the following detailed description, reference is made to the accompanying drawings which form a part of the present specification and show examples of feasible embodiments. It should be understood that other embodiments are available and structural or logical modifications can be made without departing from the scope of the invention. Therefore, the following detailed description should not be taken in a limited sense, and the scope of the embodiments is defined by the claims and their equivalents.

0030The various actions may be described as multiple separate actions to aid in understanding the embodiments, but the order of the description should not be construed to imply that these actions are order-dependent. ..

0031The description may use fluoroscopic explanations such as up / down, anterior / posterior, and up / down. Such description is used solely to facilitate discussion and is not intended to limit the application of the disclosed embodiments.

0032The terms "coupled" and "connected" can be used with their derivatives. It should be understood that these terms are not intended as synonyms for each other. In certain embodiments, "connection" can be used to mean that two or more elements are in direct physical or electrical contact with each other. "Coupling" can mean that two or more elements are in direct physical or electrical contact. However, "coupling" can also mean that two or more elements are not in direct contact with each other, but cooperate or interact with each other.

0033In the description, a phrase of the form "A / B" or "A and / or B" means (A), (B) or (A and B). In the description, a phrase of the form "at least one of A, B and C" is (A), (B), (C), (A and B), (A and C), (B and C) or Means (A, B and C). In the description, a phrase of the form "(A) B" means (B) or (AB), i.e. A is any element.

0034The description may use the term "embodiment (s)" which refers to one or more of the same or different embodiments, respectively. Further, the terms "comprising", "including", "having", etc. are synonyms when used in connection with embodiments and are generally "open". The term "including" is interpreted as "including, but not limited", and the term "having" is "at least having". The term "includes" should be interpreted as "includes, but is not limited").

0035When plural and / or singular terms are used herein, one of ordinary skill in the art can appropriately convert from plural to singular and / or from singular to plural, depending on the context and / or application. Various singular / plural substitutions may be specified herein for clarity.

0036In various embodiments, methods, devices and systems are presented that allow elastic fixation of fractures.

0037Embodiments herein allow elastic dynamic movement along the longitudinal axis of the bone plate, while stabilizing in all other directions at the fracture site to stimulate healing of the fracture due to callus formation. Provided is an osteosynthesis plate that maintains sex and enables stable fixation of fractures. In one embodiment, a "dynamic" lock plate design is described and tested in which the lock screw holes are elastically suspended within the silicon outer capsule inside the lock plate.

0038FIG. 1 is a top view of an elliptical bone plate 1 having elongated plate holes 2 arranged in a staggered pattern approximately along the longitudinal axis of the plate. The sliding element 3 exists below the surface of the bone plate 1 so that the threaded through hole 4 of the sliding element matches the elongated plate hole 2 of the bone plate 1. The sliding element 3 has a threaded through hole 4 to engage with the corresponding threaded bone fastener. The through hole 4 may be oriented substantially orthogonal to the upper surface of the bone plate 1. Through hole 4 is directed toward the longitudinal center line of the plate so that the bone fasteners inserted into the staggered / offset screw holes are directed / tilted towards the center of the bone member to which the plate is bonded. May be tilted.

0039FIG. 2 is a cross-sectional view of the bone plate 1 and the sliding element 3 passing through the threaded through hole 4. The through hole 4 is oriented substantially orthogonal to the convex upper surface of the bone plate 1. The sliding element 3 is generally rod-shaped and has a rectangular cross section. In other embodiments, other cross-sectional shapes may be used, such as squares, ellipses, curves, or curved rectangles that approximate the cross-sectional shape of the plate. The sliding element is composed of any medically acceptable material, such as, but not limited to, a metal such as titanium or stainless steel. The sliding element 3 of the correspondingly shaped recess 5 extends to the bottom plate surface 6 and extends towards the top plate surface 7 without extending through the top plate surface 7 to maintain the flexural strength of the plate. Placed inside. As shown in FIG. 2, the recess for the sliding element extends through the bottom plate to the bottom surface, and the sliding element is held in the plate by the bottom cover 9. The recess 5 is lined with a low friction member 8 to reduce friction and wear between the sliding element 3 and the recess 5. The low friction member is any medically acceptable material, such as a polymer such as, but not limited to, PEEK (polyetheretherketone). Other representative biocompatible polymers with a low coefficient of friction, such as UHMWPE (Ultra High Molecular Weight Polyethylene), may be used. Alternatively, the space between the sliding element and the recess may be filled with a silicone derivative that provides a superelastic interface, which reduces friction and / or the elastic suspension of the sliding element in the recess. Can be provided.

0040The sliding element 3 is held inside the plate 1 by a bottom cover 9 that is firmly connected to the plate 1 by laser welding, press fitting, or comparable reliable joining means after insertion of the sliding element. Therefore, the sliding element 3 is constrained within the bone plate 1 to prevent sliding perpendicular to the longitudinal axis of the bone plate 1. The sliding element 3 may be coupled to the bone member 10 by a bone lock screw 11, and the bone screw may be a screw having a threaded screw shaft portion 12 and a threaded screw head 13 (FIG. 3). One preferred lock screw has the same thread outer diameter and thread pitch at the screw head 13 and the screw shaft portion 12. The screw head 13 and the screw shaft 12 have the same pitch, that is, the inclination of the rotating spiral, while the screw shaft 12 has a single spiral, and the screw head 13 simultaneously rotates around the core diameter. It has a spiral body. In this array, the core diameter of the screw head 13 can be made larger than that of the screw shaft portion 12, and the threads are made denser. This array also has the advantage that the screw shaft engages into the threaded hole 14 of the sliding element 3 throughout the screw insertion. Therefore, it provides a means for firmly connecting the sliding element 3 to the bone member 10 at a given height above the bone surface without the need to press the sliding element or bone plate against the bone surface. Further, it prevents the screw head 13 from being pressed by the sliding element 3 without engaging into the sliding element 3. The positive lock of the bone screw in the sliding element 3 is provided by the end cap 15 of the screw head 13 that is pressed against the upper surface of the sliding element 3.

0041FIG. 4 shows an alternative embodiment of the through hole 14, in which the threaded hole 14 in the sliding element is conical. This allows a positive lock on the corresponding threaded conical screw head on the sliding element.

0042FIG. 5 is a bottom view of the bone plate 1 excluding the bottom cover 9 to visualize the sliding element 3. The longitudinal dimension of the sliding element 3 is smaller than the corresponding longitudinal dimension of the recess 5. This difference in longitudinal dimensions determines the permissible axial movement of the sliding element 3 with respect to the plate 1. This controlled axial motion is in the range of 0.2 to 2 mm, preferably 0.3 to 1 mm. A spring element such as the spring 22 pushes the sliding element 3 to a defined resting position by applying an effective spring preload in the range of 1-100N, preferably 5-50N. When the sliding element 3 exerts a force against the preload of the spring element 22, the sliding element moves with respect to the plate (linear motion along the longitudinal axis of the bone plate). When the force is removed, the sliding element 3 returns to its resting position by the spring force. An example of applying a preload to a spring element is as follows. To preload the spring element, the spring element is compressed during assembly before or during insertion of the sliding element and / or spring element into the bone plate.

0043FIG. 6 shows an alternative embodiment of a spring element in which the spring element is integrated into or part of the sliding element 3 by a series of elongated spring fingers 23 and grooves 24 (as opposed to separate springs). .. The groove 24 converts a part of the sliding element 3 into an elastic spring element.

0044FIG. 7 shows yet another alternative embodiment of the spring element, in which the groove 24 is introduced on both sides of the sliding element 3. The groove 24 converts both sides of the sliding element 3 into elastic spring elements, the spring element elastically suspends the threaded screw hole 14 inside the recess 5, and the threaded through hole 14 is bidirectional from its non-load center position. Allows translational movements.

0045FIG. 8 is a longitudinal sectional view of an embodiment of the sliding element 3 shown in association with the bone screw 11 attached to the cylindrical bone section 10. The spring 22 is retracted into the cylindrical hole 17 of the sliding element 3. The recess 5 is lined with a low friction layer 8. The lock screw 11 secures the sliding element 3 so that the plate 1 is not pressed against the bone surface 18. In an alternative embodiment using a non-locking screw, the plate can be pressed against the bone surface.

0046FIG. 9 is a cross-sectional view of a bone plate 1 elastically fixed to two corresponding sections of cylindrical bone using a bone screw 11. The spring 22 in the sliding element 3 is arranged closer to the fracture site 19. Therefore, when an external compressive force acting on the bone segment 10 is applied, it induces the translational motion / movement of the sliding element 3 with respect to the plate 1, which induces the translational motion of the bone segment 10 parallel to the longitudinal axis of the plate 1. To do. This produces a symmetrical motion between the surfaces at the fracture site 19 within the controlled motion envelope. The momentum of the fracture site is controlled by the maximum range of translational movement of the slider inside the recess 5 of the plate. Therefore, an external compressive force above the set threshold of 100-1000N, preferably 200-800N, based on the stiffness and preload of the spring element, does not produce additional motion of the sliding element 3 inside the plate. If the preload and stiffness of the selected spring element is small enough, the sliding element will reach its maximum permissible displacement with an external compressive force low enough to prevent excessive plate bending. Excessive plate bending can lead to excessive friction, wear or jamming of the sliding element 3 within its recess.

0047The elastic connection of the bone plate to the bone by an elastically suspended sliding element applies to one or more bone compartments of the fractured bone while the other bone compartments are fitted with standard bone fasteners such as non-locking. Alternatively, it can be fixed to the same bone plate using a lock screw or the like.

0048FIG. 10 is a cross-sectional view of the bone plate 1 associated with the cylindrical bone, which is attached to the bone 10 using a plurality of non-collinear bone nails 20. The bony nail 20 has a threaded head 21 and securely locks into the corresponding threaded through hole 14 of the sliding element 3. The bony nail 20 has a smooth shaft portion 25 for multiplanar fixation in the bone, which prevents transmission of forces acting in the direction of the longitudinal axis of the nail to the sliding element 3.

0049FIG. 11 is a cross-sectional view of the bone plate 1 passing through the threaded through hole 14 of the sliding element 3. The sliding element 3 is at least partially surrounded by the recess 5. In certain embodiments, the sliding element is surrounded by the top, bottom and near the center of the plate, but in certain embodiments it is substantially exposed on the sides. By leaving one side open, the sliding element can be dropped into place and silicon can be formed so that it does not need to be overlaid and the plate welded. In this embodiment, the recess 5 is formed from the side surface of the bone plate 1, penetrates to the bottom surface 6 of the plate, and extends toward the top surface 7 of the plate. The sliding element 3 is suspended in the recess 5 by the elastomeric lumen 26. The elastomer 26 is selectively joined to the recess 5 and / or a portion of the sliding element 3 to affect the desired elastic restraint of the sliding element 3 on the bone plate 1. For example, in one embodiment, the surface 27 of the sliding element 3 is joined to an elastomeric or elastomeric material. FIG. 11 shows a situation in which the sliding element suppresses movement. In addition to preventing metal-to-metal contact and abrasion, this elastic restraint of the sliding element is such that the threaded screw head is not inserted exactly parallel to the axis of the screw hole of the sliding element. Facilitates engagement with sliding elements.

0050FIG. 12 is a bottom view of the bone plate 1 excluding the bottom so that the sliding element 3 having the threaded through hole 14 can be seen. The sliding element 3 is surrounded by a recess 5 formed on the side surface of the bone plate 1 by an elastomer 26 that preferentially allows longitudinal movement. This figure shows an embodiment in which the longitudinal dimension of the sliding element 3 is smaller than the corresponding longitudinal dimension of the recess 5. This difference in longitudinal dimensions determines the permissible movement of the sliding element 3 with respect to the plate 1. This controlled range of motion is in the range of 0.1-2 mm, preferably 0.3-1 mm. In the illustrated embodiment, the sliding element 3 does not extend to the outer surface of the bone plate. FIG. 12 shows an elastomer 26 between the edge of the sliding element 3 and the edge of the recessed area 5. In another embodiment, the elastomer is an elastomer 26 that surrounds or surrounds the sliding element 3.

0051FIG. 13 is a perspective view of the bone plate 1 having the upper surface 7 and the sliding element 3 having the threaded through hole 14. This figure shows a recess in the "side of the bone plate" (ie, not the top or facing surface of the bone) through which the sliding element 3 and the elastomer 26 can be inserted.

0052FIG. 14 shows a sliding element 3 projecting downward beyond the bottom surface 6 of the bone plate 1. The sliding element 3 having the threaded through hole 14 fits in the recess. The illustrated elastomer 26 surrounds the sliding element 3. This figure shows that the internal sliding element 3 is at least partially enclosed within a cavity on the side of the bone plate (ie, a cavity that is not facing or above the bone). This figure is designed to show the portion of the slider that extends downward on the bottom surface. Still, the cavity is on the side of the plate. The surface 27 of the sliding element 3 is joined to an elastomer or elastic material.

0053In one embodiment, a bone plate having an outer surface and a bone facing surface is provided, the bone plate comprising an internal sliding element. Each sliding element includes a threaded receiving hole for a bone screw or nail with a corresponding threaded screw head. The sliding element suffers a controlled displacement parallel to the longitudinal axis of the plate, but is substantially suppressed for displacement orthogonal to the longitudinal axis of the plate. A bone screw with a threaded head can be firmly anchored in the threaded receiving hole in the sliding element without pressing the bone plate against the bone surface. Thus, the bone compartment can be fixedly fixed to the bone plate while retaining the possibility of controlled displacement parallel to the longitudinal axis of the bone plate. The amount of displacement is controlled by the motor encapsulation of the sliding element within the bone plate.

0054The sliding element is generally rod-shaped and has a rectangular cross section. In other embodiments, other cross-sectional shapes such as square, oval, curved or curved rectangles similar to the cross-sectional shape of the plate can be used. The sliding element is only required to have a size and shape that fits into the recess of the plate and a size that allows the desired momentum. The sliding element is composed of any medically acceptable material, such as, but not limited to, a metal such as titanium or stainless steel.

0055The sliding element is elastically suspended in the plate by a spring element that determines the amount of translational movement of the sliding element with respect to the plate in response to a load acting in the longitudinal direction of the plate. This elastic suspension allows dynamic movement between adjacent bone compartments attached to the bone plate in response to the weight support of the plate-interosseous fixation structure. The spring element can be a spring separate from the sliding element or can be part of the sliding element. In other embodiments, the spring element is an elastomeric material.

0056Elastic fixation between the bone and the plate via a load-responsive sliding element allows for controlled and symmetrical movement at the site of the fracture, which is known to promote fracture healing by callus formation. .. In addition, elastic fixation enhances the strength of the construct by strengthening the load distribution at the fixation points and reducing the stress concentration. Elastic fixation also reduces bone resorption and cavity formation caused by stress-shielding due to the over-rigidity of the fixation component.

0057Elastic fixation is made possible by the use of elastomers. The elastomer ensures that it adheres to at least a portion of the surface of the plate or sliding element, allowing the desired elastic restraint of the sliding element on the bone plate.

0058In certain embodiments, the elastomer has no voids (eg, air pockets) or is substantially empty. In other embodiments, the elastomer has voids that can further reduce the effective stiffness of the system by increasing the compressibility of the elastomer.

0059The elastomer can be any medically suitable elastomer such as silicon (but not limited to this). In certain embodiments, the elastomer has a modulus in the range of 0.1-50 MPa that allows for the desired amount of movement / elasticity. In certain embodiments, the modulus and formulation of the elastomeric material can vary within the elastomer. For example, two different elastomers can be used or elastomers of different thicknesses or viscosities can be used.

0060In certain embodiments, the elastomer comprises an elastomer that surrounds or surrounds a sliding element. In other embodiments, the elastomer is between the sliding element and the wall of the recess.

0061In certain embodiments, the sliding element can be removable as a single element or with an elastomer. In other words, in certain embodiments, the sliding element is incorporated into the plate and the silicone is molded to bond the sliding element and the plate together. In other embodiments, silicon can be molded and glued to the outside of the sliding element and then the component can be pushed into the plate. In this case, it is not adhered to the plate. In another embodiment of the "no-load" modular bone plate, the surgeon can insert an elastic sliding element, an inelastic locking element or a non-locking element.

0062In certain embodiments, the elastic suspension of the sliding element in the plate is obtained by two or more spring elements that determine the amount of bidirectional translational motion of the sliding element with respect to the plate in response to the longitudinal load of the plate.

0063In certain embodiments, the spring element is composed of a separate spring. In certain embodiments, the spring element is composed of an integrated spring formed of an elastic structure or material that is part of the sliding element.

0064In certain embodiments, the spring element is composed of an integrated spring formed of an elastic structure or material that is part of a plate compartment adjacent to the sliding element.

0065In certain embodiments, the spring element is formed by an elastic material (elastomer) placed between the sliding element (shown as 3 in FIG. 12) and the plate (1).

0066In certain embodiments, the spring element is formed by an elastic material (elastomer) lumen that encloses or surrounds the sliding element. For example, the elastomer is above and below the sliding element, not between the wall of the recess and the edge of the sliding element.

0067In one embodiment, the sliding element is suspended between two or more spring elements (eg, a spring element as shown in FIG. 7). This configuration allows elastic displacement in two opposite directions. FIG. 7 shows an embodiment in which the two spring elements are integral with the sliding element. In another embodiment, the spring element can be separate from the sliding element. In another embodiment, the spring element is a combination of a separate spring element and an integral spring element. In other embodiments, the spring element can be an elastomer or an elastomer. In other embodiments, the combination of separate spring elements such as springs and elastomers is possible. For example, one side of the sliding element may have a spring (separate or integral) and the spring element on the other side of the sliding element may be an elastomer.

0068In certain embodiments, it can be a combination of individual or integral spring elements and elastomer spring elements. For example, individual and / or integral spring and sliding elements can be surrounded by an elastomer. Alternatively, it can be a combination of an individual or integral spring element and an elastomeric material between the recessed wall and the sliding element.

0069In certain embodiments, the elastic suspension of the sliding elements in the plate holds each sliding element in a defined resting position and unidirectionally translates each sliding element with respect to the plate in response to a longitudinal load on the plate. Obtained by a spring element that determines the amount.

0070In certain embodiments, the fracture plate is composed of multiple through holes (more than one in certain embodiments and more than two in certain embodiments), each through hole being a sliding element and a spring element. Has. In certain embodiments, the fracture plate has sliding and spring elements of the same material, all of the same shape. In certain embodiments, the fracture plate has different shapes and / or different material sound sliding elements and / or different spring elements. For example, one section of the plate can have a separate spring element, another section of the plate can have a spring element integrated with the sliding element, and the other section can have a spring element of elastomeric material. Or other areas of the plate can employ a combination of individual, integral and / or elastic material spring elements.

0071In another embodiment, a single spring element is used to hold the sliding element in the defined resting position. This ensures a stable position of the sliding element when inserting the bone screw. Subsequent fixed body loads (such as those that occur when the patient applies weight or force to the fractured bone) initiate the movement of the sliding element, the initiation of which can be defined by the preload of the spring element. When the load is removed, the sliding element returns to its defined resting position.

0072In another embodiment, the sliding element is partially or completely embedded in a low friction layer such as a polymer membrane. This arrangement reduces friction and wear between the sliding element and the plate.

0073In another embodiment, the sliding elements and their corresponding fixing holes are configured in a staggered arrangement. See, for example, FIGS. 1, 3 and 10. Compared to sliding elements arranged along a straight line, this staggered fixation increases the stability of the fixed structure when subjected to torsional loads.

0074In certain embodiments, one or more sliding elements extend beyond the bone facing surface of the plate and raise the plate body above the bone surface when the socket is pressed against the bone surface by a non-locking bone screw. Let me. This, along with the elastic suspension of the sliding element, allows for controlled relative movement between the plate and the bone surface. See Figure 14.

0075In certain embodiments, the internal sliding element is at least partially enclosed within a cavity on the side of the plate. FIG. 11 shows a sliding element enclosed in a cavity on the side of the plate.

0076In another embodiment, the threading receiving hole of the sliding element is conical. This allows for positive locking of the corresponding threaded conical screw head in the sliding element.

0077In another embodiment, the threaded receiving hole of the sliding element is cylindrical and is used with a bone screw having the same thread outer diameter and thread pitch at the screw head and screw shaft. This has the advantage that the screw shaft engages the threaded holes of the sliding element throughout the insertion of the screw. Thereby, this embodiment prevents the screw head from being pressed against the sliding element. Allowing the screw head to easily engage into the threaded holes of the sliding element also prevents preloading of the sliding element inside the bone plate.

0078In certain embodiments, there are multiple bone screws (see, eg, FIGS. 3 and 9). In certain embodiments, the device further comprises one or more non-collinear bone pegs with a threaded head and a smooth peg shaft (see, eg, FIG. 10). In another embodiment, one or more sliding elements can be connected to the bone using a peg with a threaded head that securely engages with the threaded holes in the sliding element. By using lock pegs instead of lock screws, the risk of preloading of sliding elements inside the plate is reduced. Lock pegs can be inserted in a multi-planar configuration to enhance fixation strength. In this case, at least two threaded holes in the sliding element have a central axis that is not collinear.

0079In certain embodiments, the plate comprises threaded and / or unthreaded screw holes.

0080In another embodiment, the sliding element is located only in a particular section of the bone plate, another section of the bone plate having threaded or unthreaded holes (as used in the industry). In one embodiment, the spring element and sliding element are located in one section of the plate, another section of the plate has threaded or unthreaded holes without the spring element and sliding element. Bone plates with standard threaded holes or standard non-threaded holes (as used in the industry) without spring and sliding elements (referred to herein and as static receiving holes) to the bone surface. Bone compartments with sliding / spring elements allow elastic fixation of the corresponding bone compartments, while allowing compression and firm fixation of the plate, interosseous movement in response to intermittent loads of the fixation construct. Retain the possibility of getting. For example, on one side of the fracture, the bone plate comprises an elastic suspension with spring and sliding elements, and on the corresponding bone segment on many sides of the fracture, the bone plate comprises a resting hole (elasticity). Does not have suspension). Also, in certain embodiments, the sliding element / spring element and the resting hole can be used together in the same section of the bone plate. For example, every other hole can be a static receiving hole (the other holes are elastic suspension through holes). In another embodiment, it is a mixture of elastic suspension (using sliding and spring elements) and resting holes, which can be the same across the bone plate across the fracture. In other embodiments, the mixture of static receiving holes and elastic suspension can vary within the plate. For example, one side of a fracture has more elastic suspension and fewer resting holes, and on many sides of the fracture it has more resting holes than elastic suspension. In other words, different parts of the bone plate can each use different combinations.

0081In another embodiment, the sliding element and one or more screw holes can be combined in the same plate compartment. This allows the plate to be temporarily secured to the bone surface using standard non-locking screws, facilitating the attachment of the locking screws to the sliding element.

0082The present invention also provides a method of fixing a fracture using a flexible plate. In certain embodiments, the method traverses the fracture by nearly aligning the fractured bone members and by means of multiple bone fasteners that are tightly connected to the receiving holes of the plurality of sliding elements elastically suspended in the bone plate. Includes hitting the bone plate. The sliding element is configured to allow controlled translational motion parallel to the longitudinal axis of the bone plate while preventing displacement substantially orthogonal to the longitudinal axis of the plate. The bone screw is firmly fixed to the sliding element without pressing the bone plate or sliding element against the bone surface.

0083In certain embodiments, the pits preferentially extend to the longitudinal axis of the plate while substantially suppressing the movement of one or more pits in a direction orthogonal to the top surface or facing surface of the bone plate. Suspended to allow translational movement with respect to the plate along.

0084In certain embodiments, the spring element suspends the receiving hole in a neutral position with respect to the plate in the absence of a load and, in response to the load, exerts a controlled elastic translational motion of the receiving hole with respect to the plate. Acts as an elastic spring that enables.

0085In certain embodiments, the flexible element dampenes the transmission of impact loads between the plate and the bone member, enhancing the stability of the fixation structure.

0086In certain embodiments, the flexible element enhances the distribution of load transfer between multiple fixation elements associated with a single bone segment. For standard stationary plates, one screw typically receives more load than the other screws due to imperfect alignment. By using the elastic suspension of the present invention (elastically suspended sliding element), the screw can be displaced so that the load is distributed across the screw and the elastic element may not even be loaded.

0087In certain embodiments, the flexible element prevents direct contact between the receiving hole and the plate, at least in part, to reduce surface wear and material fatigue.

0088In certain embodiments, the elastic suspension of the two or more receiving holes and plates is realized on one side of the fracture, while the corresponding bone compartments are attached to the stationary receiving holes.

0089In certain embodiments, elastic suspension of two or more receiving holes and plates is realized on both sides of the fracture.

0090In certain embodiments, the elastic suspension of the two or more receiving holes and the plate substantially reduces the axial stiffness of the fixed structure in the range of 40-90% compared to the bone plate structure having the stationary receiving holes. To do.

0091In certain embodiments, one or more flexible elements capture the presence or magnitude of load transfer between the receiving element and the plate as a means for estimating the progress of fracture healing. Includes sensors for measuring displacement, pressure or load. For example, a sensor can be implanted to help measure when the bone has healed. For example, when a sensor measures displacement, it can be expected that the displacement of the portion will decrease over time as the bone heals. When the sensor measures the load, the load on the plate can be expected to decrease with bone healing.

0092In certain embodiments, the elastomeric material can comprise an elastomeric lumen, the elastomeric material of one or more flexible elements providing a means for generating energy to provide transient power to the sensor. Including.

0093In certain embodiments, any of the bone plates described above with reference to FIGS. 1-14 can be designed as "smart" bone plates capable of measuring one or more dynamic parameters after implantation. An example of a measurable parameter is movement in the fracture space that can be used to assess bone healing. Compared to standard monolithic lock plates, dynamic bone plates with sliding elements suspended and separated from the plate are uniquely designed to incorporate one or more sensors.

0094FIG. 15 is a cross-sectional view of a bone plate 101 similar to the bone plate 1 shown in FIG. As shown in FIG. 15, the bone plate 101 can include a sliding element 103 with a threaded through hole 114. The sliding element 103 can be enclosed in a recess 105 formed on the side surface of the bone plate 101 by an elastomeric lumen 126 that allows longitudinal movement. As shown in FIG. 15, the longitudinal dimension of the sliding element 103 is smaller than the corresponding longitudinal dimension of the recess 105. The difference in longitudinal dimensions determines the permissible movement of the sliding element 103 with respect to the plate 101.

0095Further, as shown in FIG. 15, the bone plate 101 may include one or more sensors operably coupled to the sliding element 103 or the body of the bone plate 102. The sensor 130 can be operably coupled to the transmitter element 132, which can be configured to communicate with the receiver element 134 located outside the bone plate 101. In one embodiment, the transmitter element 132 can also act as a receiver and the receiver element 134 can also act as a transmitter. Such devices are commonly known as transsivas. Any suitable radio communication means can be used, including, but not limited to, radio frequency telemetry, radio frequency identification, Bluetooth, Zigbee, near field communication, internal communication and the like. The transmitter element 132 includes a power source incorporated therein, or the power source can be incorporated into the bone plate 101 separately from the transmitter element 132. Alternatively or additionally, an external power source can be incorporated into the receiver element 134 or installed as a separate external element.

0096The sensor 130 can include a bone plate 101, a sliding element 103, an elastomer Lumen 126 or any sensor suitable for measuring dynamic parameters of these combinations. In one embodiment, one or more sensors 103 can be incorporated into a bone plate 101, a sliding element 103, an elastomer layer 126 or a combination thereof. The sensor 103 can be self-powered or powered by an external power source. In one embodiment, the sensor 130 can be incorporated into the bone plate 101 in a manner suitable for assessing the movement of the sliding element 103 with respect to the bone plate 101 to assess the performance of the bone plate 101. In another embodiment, the sensor 130 can be configured to measure the relative position of the sliding element 103 with respect to the bone plate 101. In another embodiment, the sensor 130 can be configured to directly measure the displacement of the sliding element 103. In yet another embodiment, the sensor measures the pressure within the elastomer or the pressure applied by the elastomer 126 to the adjacent body of the bone plate 101 as a means of indirectly assessing the motion of the sliding element 103. Can be configured to. When evaluating motion, the sensor 130 can be configured to measure longitudinal motion of the sliding element 103. Motion in other directions can also be evaluated by the sensor 130.

0097Instead of or in addition to the sensor, the bone plate 101 can include at least one accelerometer. In one embodiment, two accelerometers are used, one placed on or in the body of the bone plate 101 and the other placed in the sliding element 103 or elastomeric lumen 126 to slide. The relative acceleration of element 103 can be measured.

0098To further illustrate some of the advantages of dynamic bone plates described herein, two examples are shown below. Specifically, Example 1 shows the results of a first biomechanical study to show how well an elastic suspension screw hole in a locked osteosynthesis plate can dampen an impact load. Example 2 shows the results of a second biomechanical study to show how much a dynamic lock plate can provide axially symmetric dynamization to stimulate fracture healing.

0099Example 1

0100Abstract: The high stiffness of the lock plate construct can contribute to iatrogenic fractures and impact fatigue. Conversely, impact damping by elastic fixation is a major design strategy for increasing the durability of load-bearing structures exposed to long-term dynamic loads. This example evaluated the impact damping provided by a "dynamic" lock plate design in which the lock screw holes are elastically suspended within the silicon outer capsule inside the lock plate.

0101In a biomechanical study, impact attenuation was evaluated for three separate fixation components for bridging the 10mm fracture space of the femoral trunk substitute: standard lock plate, dynamic lock plate and Ilizarov ring fixture. First, the three fixed constructs were characterized by measuring their axial stiffness. The construct was then exposed to a predetermined range of axial impact loads to quantify the damping of force transmission.

0102Compared to the standard lock plate construct, the dynamic plate construct was 58% less rigid (p &lt;0.01) and the Ilizarov construct was 88% less rigid (p &lt;0.01). The impact damping was found to correlate inversely with the stiffness of the construct. Compared to the standard plate construct, the dynamic plate construct and the Ilizarov construct were found to attenuate the transmission of impact loads by up to 48% (p &lt;0.01) and 74% (p &lt;0.01), respectively. Therefore, the results of biomechanical studies have demonstrated that a dynamic lock plate provides significantly greater impact damping than a standard lock plate by increasing the damping of the impact load if the stiffness of the construct is low.

0103Background: The osteosynthesis plate construct must withstand long-term load transfer across the fracture until the process of fracture healing gradually restores physiological load transfer. Clinically, this plate osteosynthesis is a competition between fracture healing and poor fixation, and long-term or overloading increases the risk of loosening or fatigue failure of the fixation component.

0104Elastic suspension is a major design strategy for increasing the durability of components that are exposed to dynamic loads over the long term. In the case of impact loads, the elastic suspension can act as a shock absorber to attenuate the magnitude of the load and prevent structural damage by distributing the impact energy over a long period of time. The traditional Ilizarov apparatus, which is unique to fracture fixation, elastically suspends the fracture fragment inside the outer circular frame with a thin Kirschner wire. Conversely, modern lock plates represent a very rigid fixing method, and lock screws with threaded screw heads are securely locked into threaded plate holes. These lock plate constructs can improve fixation in weak osteopenic bone compared to traditional non-locking constructs. However, in the absence of elastic fixation, the lock plate construct has been found to induce stress concentration at the screw-bone and screw-plate interface due to its tight fixation, resulting in considerable fracture and implant fatigue. Also shows the risk of.

0105To enable elastic fixation with a lock plate, the inventor has developed a "dynamic" lock plate. In this lock plate, the lock screw holes are elastically suspended within the silicon outer capsule inside the lock plate. The inventor hypothesized that the elastic suspension provided by the dynamic lock plate could dampen the impact load transmitted through the osteosynthesis structure as compared to contemporary rigid lock plates. For historical comparison with highly flexible fixation systems, the inventor further provided that the tension wire suspension of the Ilizorov fixture provides superior impact load damping compared to firm fixation with lock plates. Then I made a hypothesis. The goal of biomechanical research was to chart the correlation between the stiffness of the osteosynthesis structure and its ability to dampen the transmission of impact loads. Since such impact damping behavior can provide clinical benefits, a reduction in peak load could potentially reduce the risk of implant crushing, fracture, or immobilization.

0106Methodology: In biomechanical studies, impact was given to three separate fixation constructs applied to bridge the 10mm fracture void in the femoral trunk substitute: the standard lock plate, the dynamic lock plate and the Ilizarov ring fixture. The decay was evaluated. First, three fixed constructs were characterized by measuring their axial stiffness under a quasi-static load. Then, an axial impact load force in a predetermined range representing the magnitude of the physiological load was applied to the construct. Impact damping was quantified by measuring the magnitude and length of force transmitted through each construct in response to a well-defined impact load.

0107The standard lock (standard) and dynamic lock (dynamic) plates have the same cross-sectional shape that represents a typical large fragment plate for the fixation of femoral fractures, as shown in Figure 16A. have. Standard and dynamic plates have 9 holes, 204 mm in length, 18 mm in width and 6 mm in thickness, and are manufactured from Ti6Al4V ELI titanium alloy (F136-13,2003). The only difference between the standard plate and the dynamic plate is that the locking holes in the dynamic plate are integrated into a separate sliding element that is elastically suspended in the silicon outer capsule in the side pocket of the plate, as shown in Figure 16B. That is. The pocket shape allows about 1 mm of axial translation of the sliding element, but all remaining degrees of freedom are strictly suppressed. Thus, the elastic suspension provides stable fixation against bending and twisting loads while allowing controlled axial movement across fracture voids in response to compressive loads. Silicon Suspension is a medical grade silicone elastomer (HCRA) that can be implanted for a long time with a hardness of 50A durometer. 4750, Applied Silicon, Santa Paula, CA, USA) was transferred and molded. Standard and dynamic plates accept the same 5.0 mm diameter bicortical self-tapping locking screw.

0108To minimize variability between specimens, the plate is a tough cylindrical substitute (3403-10, Vashon, WA, USA) representing the femoral trunk with a diameter of 27 mm and a wall thickness of 7 mm. ) Was evaluated. A plate was used to bridge the 10 mm wide incisal space in the center of the 270 mm long bone trunk substitute. This incisal space mimicked the biomechanical constraints of comminuted fractures that depended on full load transfer through the osteosynthesis construct due to lack of bone continuity at the fracture site. Standard and dynamic plates use three screws located in lock holes 1, 3 and 4 from the end of the plate on either side of the incisal space, as shown in Figure 17A (the central lock hole is above the incisal space). Placed in and left empty) attached. The Ilizarov apparatus consists of two 180 mm diameter rings above and below the incisal space, as shown in Figure 17B. Two 1.8 mm Kirschner wires were applied to each ring to give hearing up to 130 kg.

0109Stiffness and impact damping of the construct were evaluated for each of the three groups (standard, dynamic and Ilizarov) for three specimens. The stiffness of the construct was evaluated on a Servo-Pressure Material Test System (Instron 8800, Norwood, Mass.). The construct was tightly connected to the load cell distally and to the actuator proximally. The actuator applied axial static compression up to 1000N in 50N increments. The stiffness of the construct was inferred by dividing each load increment by the corresponding actuator displacement increment.

0110Impact damping was tested using a monorail drop test system for the application of controlled and scalable impacts to fixed constructs as shown in Figure 17C. The drop test system was designed and validated to comply with impact test standards (F1446-13, 2013) and correlated with previous impact test simulations in biomechanical research. Axial impact is 5, 10, 20, 40 and 60 mm with increasing drop height h_dropInduced by vertically dropping a mass of 2.0 kg from. This is an energy E of 0.1-1.2 joules_IInduced a shock in the range of. The impact was concentrated on the proximal end of the vertically aligned diaphyseal construct. The distal end of the construct was firmly anchored in the center of a uniaxial load cell (Instron 12619, Norwood, Mass.). This load cell recorded the impact force Fr transmitted through the osteosynthesis construct. The Fr signal was recorded at a sample rate of 20 kHz using a data acquisition system (PCI-6221, Austin National Instruments, Texas, USA) and processed with a 600 Hz low frequency filter as specified by the impact test standard (F1446-13, 2013). did. After that, the Fr signal is post-processed, and the peak force F transmitted at the time of impact is applied._{T, peak}And impact duration t_IWas measured. Impact duration is F_TF from the start of the signal_{T, peak}Evaluated up to. Impact drop height h in the range of 5 to 60 mm for the three components of each group_dropTested in each of.

0111F to statistically analyze the impact force results_{T, peak}And t_IValues are compared between three fixed constructs using ANOVA at a significance level of α = 0.05, and then Bonferroni adjusted pair-wise to measure significant differences between the pairs of constituents. comparison) was performed.

0112Results: Axial load-displacement history for compressions up to 1000 N showed invariant stiffness for standard constructs, but gradually increased for dynamic and Ilizarov constructs, as shown in Figure 18A. .. Specifically, the standard plate construct was relatively rigid at a load of 300 N (3213 N / mm) and a load of 1000 N (3265 N / mm). The average stiffness of the dynamic plate construct increased from 646 N / mm at 300 N load to 992 N / mm at 1000 N load. The average stiffness of the Ilizarov construct increased from 138 N / mm at 300 N to 260 N / mm at 1000 N. As shown in FIG. 18B, at a compression load of 300 N, the dynamic construct is 58% less rigid than the standard plate construct (P &lt;0.01) and the Ilizarov construct is 88% less rigid (P &lt;0.01).

0113Transmitted force F in impact test_{T, peak}Increased as the level of impact energy increased in power correlation as shown in FIG. 19A. For a given impact energy level, the stiffest construct is the highest F_{T, peak}Therefore, the amount of impact attenuation allowed was the smallest. Impact duration t_IWas seemingly invariant for a given fixed structure regardless of impact energy, as shown in FIG. 19B. However, t between the components₁Fluctuated by an order of magnitude, with stiffer constructs having shorter impact durations. The average impact durations of the standard, dynamic and Ilizarov constructs were 0.7s (SD0.03s), 1.7s (SD0.09s) and 7.5s (SD0.56s), respectively.

0114The dynamic plate structure averages only 488N (SD64N) F compared to the standard lock plate._{T, peak}Was significantly reduced. F_{T, peak}As shown in FIG. 20A, the decrease ranged from 48% (p &lt;0.01) at a drop height of 5 mm to 22% (p &lt;0.01) at a drop height of 60 mm. This F_{T, peak}The decrease in impact duration t, as shown in a typical force history graph, as shown in Figure 20B._IConsistent with the increase in. The dynamic plate construct is t compared to the standard lock plate construct._IWas increased by an average of 133% (p &lt;0.01).

0115Ilizarov construct is F compared to standard lock plate_{T, peak}Was significantly reduced. F_{T, peak}The decrease ranged from 60% (p &lt;0.01) at a drop height of 5 mm to 74% (p &lt;0.01) at a drop height of 60 mm. The Ilizarov construct averages 325% (p &lt;0.01) t compared to the standard construct._IWas significantly increased.

0116Argument: For fracture fixation, the Ilizarov ring fixture provides a unique damping mechanism by the elastic suspension of the external fixator ring on the wire "spokes". Due to its excellent durability, the Ilizarov apparatus is often used for revision surgery when the intramedullary nail or plate construct cannot withstand extended weight bearings in the case of delayed or unfused fusion. used.

0117On the other hand, as far as the present inventor knows, the impact damping mechanism has not been studied or realized in the osteosynthesis plate. The plate construction is typically an order of magnitude larger and stiffer than the Ilizarov apparatus. Unlike the Ilizarov apparatus, the plate construct bears the well-known risk of inducing iatrogenic fractures at the end of the plate. Modern lock plates induce higher stress concentrations at the plate edges, and high stress concentrations have been demonstrated to reduce the strength of the construct by up to 22% compared to standard non-lock plates. Furthermore, the incidence of implant fatigue and improper fixation of the lock plate construct has been found to be as high as 12%.

0118The use of silicone elastomers in plate osteosynthesis is a new concept, but long-term implantable silicone has already been used clinically for permanent impressions such as knuckles. Unlike silicone gels, the silicone elastomers used in knuckles and the dynamic lock plates of this biomechanical study have very high biocompatibility and bioinactivity.

0119The results of this biomechanical study demonstrated that the impact damping element of the dynamic lock plate can significantly reduce load transfer compared to the standard lock plate. The hardest construct (standard) has the smallest amount of damping and the highest peak force F._{T, peak}It was found that the impact damping inversely correlates with the stiffness of the construct. The observation that the dynamic lock construct reduced the peak force while increasing the impact duration is consistent with the damping mechanism of the shock absorber that reduces the peak load by distributing the impact energy over a long impact duration. This impact damping effect of the dynamic construct provides clinical benefits and the reduced peak load transfer can mitigate the risk of implant breakage, fracture or immobilization. In addition, elastic fixation of the dynamic lock plate reduces the stiffness of the construct compared to the standard lock plate, which increases the momentum induced at the fracture site. Since the biological fracture healing by callus formation is stimulated by interosseous movement, the elastic fixation provided by the dynamic plate can further support the biomechanical environment required to promote healing.

0120In conclusion, the results of this biomechanical study demonstrated that less rigid fracture fixation constructs are more likely to attenuate the transmission of impact loads. Compared to standard lock plates, dynamic lock plates have significantly lower stiffness and significantly attenuate the transmission of impact loads.

0121Example 2

0122Abstract: Symmetrical axial dynamization of lock plate constructs with far cortical locking-FCL screws has been found to significantly enhance the speed and strength of fracture healing. The FCL derives its dynamization from the flexion of the elastic screw shaft, so it cannot effectively scale to the short screws required for fractures of small diameter bones. To address this scaling limitation, this biomechanical study uses an elastic suspension of lock holes in the plate to derive a new dynamic lock that derives symmetric axial dynamization regardless of the length of the lock screw. The plate was evaluated.

0123Standard lock (standard) plate constructs and dynamic lock (dynamic) plate constructs were tested in a femoral shaft stem bridge plate model to determine the amount and symmetry of interosseous motion in response to axial load. The properties were measured and the rigidity of the construct under axial load, twisting and bending was evaluated. The strength and failure mode of the components were then measured by dynamically applying axial compression, twisting and bending loads to the standard and dynamic components until failure. In addition, strength tests were repeated in an osteoporotic femoral stem certification model to measure component strength and failure mode in the worst-case scenario of bridge plates in osteoporotic bone.

0124One body weight (700 N) axial load of the standard plate construct resulted in less than one-third asymmetric interosseous movement in the near cortex (0.1 ± 0.01 mm) than in the distant cortex (0.32 ± 0.02 mm). Compared to the standard plate construct, the dynamic plate construct enhances symmetric movement by 0.32 mm in the near cortex and 0.33 mm in the distant cortex. The dynamic plate construct has 77% lower axial stiffness (p &lt;0.001), 15% lower torsional stiffness (p = 0.03) and similar flexural rigidity (p = 0.27) compared to the standard lock construct. Between the dynamic lock construct and the standard lock construct, except for the twist test of the non-osteoporosis specimen (in this test, the dynamic construct was 21% stronger than the standard construct (p = 0.01)). ) There was no noticeable difference under all test conditions.

0125The dynamic plate construct has been shown to symmetrically enhance interosseous motion and deliver axially controlled dynamization, and is at least comparable to the standard plate construct in terms of strength. found. Dynamic plates can be applied using standard lock screws to symmetrically enhance axial dynamization and promote natural bone healing through callus formation.

0126Background: Axial dynamization of osteosynthesis constructs can be a determinant in the competition between fracture healing and fixation construct failure. Over 50 years of research have consistently demonstrated that controlled axial dynamization can improve the speed and strength of fracture healing by dynamically stimulating secondary bone healing through callus formation. .. A groundbreaking study by Goodship and Kenwright demonstrated that 1 mm axial dynamization provides more than 3 times stronger healing and more than 2 times faster healing than firm fixation (Goodship AE,). Kenwright J. "Effects of Induced Microlocation on Healing Experimental Tibial Fractures", J BoneJoint Surg Br, 1985; 650-5). Conversely, it is sufficient that deficient fracture motion caused by an overly rigid fixed structure can suppress secondary fracture healing and contribute to delayed fusion, non-union and poor fixation. There is evidence. Rigid fixation is a principle requirement for primary bone healing in which anatomical reduction and interosseous compression are used to suppress callus formation. However, perfect reduction and absolute stability are difficult to obtain, and stress blockade tends to induce osteolysis. Primary bone healing is slower and weaker than secondary bone healing and carries a significant risk of re-fracture.

0127The lock plate provides fixed angular stability and enables a biological bridge plate technique that emphasizes maintenance of blood supply and functional reduction over anatomical reduction and interskeletal compression. In the absence of anatomical reduction and interskeletal compression, the locked bridge plate structure relies on secondary bone healing. However, the initial stiffness of the lock plate construct is comparable to that of conventional plate constructs designed to maximize stiffness for primary bone healing. The lock plate structure retains its initial stiffness for a long period of time, unlike conventional non-lock plates (which gradually loosen over time).

0128The FCL screw or dynamic lock screw (DLS) allows symmetrical interosseous movement controlled by elastic fixation of the screw shaft, allowing axial dynamization of the lock plate construct. Fracture healing studies in sheep tibia have shown that axial dynamization of FCL constructs provides symmetric callus bridging on all cortical surfaces, producing 157% stronger healing compared to standard lock plates. (Bottlang M, Lesser M, Koerber J, Doornink J, von Rechenberg B, Augat P, Fitzpatrick DC, Madey SM, Marsh JL. J Bone Joint Surg Am, 2010; 92-7: 1652-60). Clinically, 31 FCL-stabilized predictive observational studies of 31 consecutive distal femoral fractures reported no implant or immobilization defects, an average time to fusion of 16 weeks and a non-union rate of 3% (Bottlang M). ,, Fitzpatrick DC, Sheerin D, Kubiak E, Gellman R, Vande Zandschulp C, Doornink J, Earley K, Madey SM. , 2014; 28-4: 181-8). While these data support the need and effectiveness of axial dynamization of the lock plate construct, FCL and DLS screws cannot be scaled to short screws that can be applied to fractures of small diameter bones (" (Because a sufficiently long screw shaft is required for elastic fixing).

0129To address this scaling limitation, this biomechanical study evaluated a new strategy called the dynamic plate method that derives symmetric axial dynamization regardless of the type and length of lockscrew used. In one example of the dynamic plate used in this biomechanical study, the lock hole is elastically suspended within the plate by a silicon outer capsule that controls the permissible axial momentum, as shown in FIGS. 21A and 21B. .. This biomechanical study tested the hypothesis that dynamic plates can provide symmetrically controlled axial dynamization while maintaining strength comparable to standard lock plate constructs.

0130Method Description: Standard lock plate and dynamic lock plate constructs were tested with axial compression, twisting and bending in a bone trunk bridge plate configuration. First, a stiffness test of standard and dynamic plate constructs was performed as a substitute for the non-osteoporotic femoral trunk to measure the amount and symmetry of interosseous motion and the stiffness of the construct in axial compression, twisting and bending. It was carried out in each main load mode. After that, the failure in each load mode was tested to measure its strength and failure mode. Failure tests were also repeated in an osteoporotic femoral trunk certification model to measure component strength and failure modes in the worst-case scenario of bridge plates in osteoporotic bone.

0131Standard and dynamic plates have the same cross-sectional shape that represents a typical large fragment plate for fixation of femoral fractures. The standard and dynamic plates have eight holes, are 204 mm long, 18 mm wide and 6 mm thick, and are made of Ti6A14V ELI titanium alloy. The only difference between the standard plate and the dynamic plate is the individual sliding elements in which the lock holes of the dynamic plate are elastically suspended within the silicon encapsulation inside the plate side pockets, as shown in FIGS. 21A and 21B. It was incorporated into. The side pockets are arranged in an alternating pattern from both sides of the plate, resulting in staggered locking hole constructs. The shape of the pocket allows about 1 mm of axial translation of the sliding element, but strictly suppresses all remaining degrees of freedom. Thus, the elastic suspension allowed controlled axial motion across the fracture void in response to compressive loads, while providing stable fixation against bending and torsional loads. Silicone suspension is a medical grade silicone elastomer (HCRA) that can be implanted for a long time with a durometer hardness of 50A. 4750, Santa Paula, CA, USA Applied Silicon) was transferred and molded. Standard and dynamic plates accepted the same 5.0 mm diameter self-tap lock screw. Plates were evaluated in a standard bridge plate configuration in a femoral trunk substitute with a 10 mm fracture space. This voided osteotomy simulated the biomechanical constraints of comminuted fractures that depended on full load transfer through the osteosynthesis construct due to the lack of bone continuity at the fracture site . The plate is attached with three screws located in the first, second and third holes from the fracture site. The central lock hole that covers the incisal space remains empty, producing a 36 mm plate span over the space. All screws were tightened to 4 Nm and the plate was raised 1 mm above the surrogate surface with temporary spacers to simulate biological fixation that maintained periosteal perfusion.

0132Plates were evaluated on representative femoral stem specimens to minimize variability between specimens and to be consistent with previous studies for comparison of results. Plate assessments in non-osteoporotic bone were performed on a tough cylindrical bone substitute (3403-10, Vashon, Washington, USA) representing a medium-sized femoral trunk. The diaphyseal substitute was made of a short fiber reinforced epoxy compound with an outer diameter of 27 mm and a wall thickness of 7 mm and certified to mimic the awkwardness of cortical bone fractures. A certified model of osteoporotic femoral stem was used to evaluate plates in weak bone. This model is made of reinforced epoxy with 27 mm and 2 mm diameter cortex and 10 pcf (0.16 g / cm).³) Consists of a column core machined from solid rigid pre-urethane foam. To reduce the amount of bone trunk substitute required, the substitute was applied to only one side of the bridge plate construct. On the other side, the plate was fixed to a reusable aluminum cylinder with a diameter of 27 mm. The cylinder isolates the failure of the component to the side of the substitute.

0133Standard and dynamic plate constructs were tested for axial compression, twisting and bending using a biaxial material testing system (Instron 8874, Canton, Mass.), As shown in Figure 22A. The constructs were tested to failure under each load mode in 3 non-osteoporotic and 3 osteoporotic bone stem substitutes (36 specimens in total). Axial compression keeps the distal end of the specimen firmly attached to the load cell to mimic the axial loading configuration of previous studies (Bottlang M, Doornink J, Fitzpatrick DC, Madey SM. It can reduce the rigidity of locked plate constructs while preserving strength ", J BoneJoint Surg Am 2009; 91-8: 1985-94; Stoffel K, Booth G, Rohrl SM, Kuster M. "Comparison of conventional plates vs. lock plates in intra-articular calcaneal fractures: biomechanical studies in human corpses", Clin Biomech (Bristol, Avon) 2007; 22-1: 100 -5; and Marti A, Fankhauser C, Frenk A, Cordey J, Gasser B. "Biomechanical Assessment of Minimally Invasive Stabilization for Internal Fixation of Distal Femoral Fracture", J Orthop Tauma 2001; 15-7: 482-7), Proximal via Spherical Bearing In addition to. Twisting was applied around the axis of the bone trunk shaft as shown in FIG. 22B. Bending was applied in a 4-point bending setting to generate a uniform bending moment over the entire plate length as shown in Figure 22C. The upper and lower cylindrical supports were separated by 290 mm and 400 mm, respectively. The plate was placed on the tension side to induce bending in void closure mode. First, stiffness tests were performed under axial compression, twisting and bending in non-porosity bone substitutes by applying loads up to 1 KN, 10 Nm and 10 Nm, respectively. The strength of the construct was then measured by gradually applying a dynamic load until failure. Static preload L_PREAfter adding L_DYNA sinusoidal load with the load amplitude of was applied at 2 Hz. Every 100 load cycles, this load amplitude is gradually increased until a component failure occurs._DYNIt increased little by little. Preload L of 50N, 1Nm and 1Nm for axial compression, twisting and bending_PREAnd 100N, 1Nm and 1Nm stepwise load amplitude L_DYNWere selected respectively. This gradual load increase allowed dynamic loading until failure while reaching failure within a reasonable number (&lt;10,000) of load cycles for each component. Failure of the component was defined by the one with either significant damage or depression threshold first. Depression d_sRepresents an irreparable collapse after load removal when measured by actuator position and is caused by bending or loosening of the implant. Thresholds d of 1 mm, 5 degrees and 1 mm for compression, twisting and bending, respectively_sSeemed to direct the initiation of component failure in the absence of significant damage. Depression d_sWas evaluated from the displacement and rotation reports of the actuators of the test system.

0134The performance of standard and dynamic plate constructs is described by the amount and symmetry of their interosseous axial motion, the stiffness of the constructs, the strength of the constructs and the failure mechanism. d_AVGThe amount of axial dynamization represented by is measured by measuring the interosseous motion in the near and far cortex in response to increasing axial load with two digital calipers with a resolution of 0.01 mm and averaging them. evaluated. The symmetry of axial dynamization is near cortex (d_NC) And distant cortex (d_FC) Was evaluated by comparing the interosseous movements. The stiffness of the construct was evaluated for compression, twisting and bending. Compressive stiffness is the axial load applied to the interosseous movement d_AVGCalculated by dividing by. The torsional stiffness was calculated by dividing the torsional amplitude by the rotational amplitude α of the actuator around the bone trunk axis. The length of the unsupported test piece was multiplied by the torsional stiffness to derive the torsional stiffness. Flexural rigidity is EI = Fa²It is expressed by the formula (3l-4a) / 12y. Here, F is the total force, l = 400 mm is the distance between the lower supports, a = 55 mm is the distance between the lower support and the upper support, and y is the upper support. Is the displacement of. The component strength is the peak load L in the gradual dynamic load until failure._MAXIt was stipulated as. Failure modes visually analyzed the presence of hardware failures, immobilizations and fractures.

0135For statistical analysis, stiffness and strength results were compared individually between the dynamic group and the standard group for each load mode. In addition, the axial dynamization parameter d in the near and distant cortex_NCAnd d_FCWas compared within the group. Significant differences were detected using a two-tailed, unpaired Student's t-test with a significance level of α = 0.05.

0136RESULTS: The dynamic construct produced significantly greater interosseous motion than the standard construct by symmetrically enhancing motion in the near and far cortex. "Toe-touch" Axial dynamization of dynamic constructs at 200 N axial load, which represents weight support d_AVG(0.22 ± 0.05 mm) was more than four times that of the standard construct (0.05 ± 0.01 mm), as shown in FIG. 23A. The standard construct required 700 N to obtain 0.2 mm axial dynamization (representing the minimum motion threshold known to simulate callus formation). However, this 700N load of the standard construct induces asymmetric dynamization and, as shown in Figure 23B, near-cortical movement (d)._NC= 0.10 ± 0.01 mm) remains below the 0.2 mm stimulus threshold and distant cortical movement (d)_FC= 0.32 ± 0.02 mm, less than one-third of p &lt;0.001). As shown in FIG. 23B, the dynamic construct symmetrically improved this dynamization by 0.32 mm in the near cortex and 0.33 mm in the distant cortex compared to the standard construct. Near cortical motion (d) in standard constructs, even with a maximum load of 1000 N for stiffness evaluation_NC= 0.15 ± 0.01 mm) remains below the 0.2 mm threshold and near-cortical movement (d) in the dynamic construct_NC= 0.53 ± 0.08 mm, less than one-third of p &lt;0.001).

0137At the axial load, the initial stiffness (911 ± 165 N / mm) of the dynamic construct was 77% lower than the initial stiffness (3960 ± 230 N / mm) of the standard construct, as shown in FIG. 24A. At loads above 200 N, the dynamic construct exhibited a secondary stiffness of 1732 ± 140 N / mm. In torsion, the torsional rigidity of the dynamic structure (0.44 ± 0.93 Nm)²/ °) is the torsional stiffness (0.53 ± 0.03 Nm) of the standard construct, as shown in Figure 24B.²/ °, 15% lower than p &lt;0.03). In bending, the flexural rigidity of the dynamic structure (81.9 ± 7.6 Nm)²) Is the flexural rigidity (75.3 ± 1.3 Nm) of the standard structure as shown in Fig. 24C.², P = 0.27).

0138Referring to FIG. 25A, in axial compression, all dynamic and standard constructs withstood a load cap of 7000 N, or about 10 times the body weight load, without failure. In twisting, as shown in Figure 25B, the dynamic construct withstood a load (40 ± 1 Nm) 25% higher than the standard construct (32 ± 2 Nm, p = 0.01). The dynamic configuration failed due to a break in the plate pocket containing the sliding element. The standard construction failed due to breakage of all three screws between the elevated plate and the bone due to repeated screw bending in periodic twisting. In bending, the strength of the dynamic construct (82 ± 5 Nm) was comparable to the strength of the standard construct (79 ± 6 Nm, p = 0.54), as shown in FIG. 25C. The dynamic construct failed due to a breakage of the substitute passing through the screw hole at the end of the plate. The standard construction failed due to bending of the plate through the central screw hole that covers the fracture space.

0139Referring to FIG. 26A, in axial compression, the strength of the dynamic construct (4533 ± 322 Nm) was comparable to the hardness of the standard construct (4967 ± 322 Nm, p = 0.17). All constructs failed due to a combination of screw bending and screw depression in the near cortex, which induced a cortical fracture line between the screw holes.

0140In twisting, the strength of the dynamic construct (23 ± 2 Nm) was comparable to the strength of the standard construct (25 ± 4.6 Nm, p = 0.54) as shown in FIG. 26B. The twist induced a spiral fracture at the end of the plate in all constructs. In bending, the strength of the dynamic construct (38 ± 3 Nm) was comparable to the strength of the standard construct (31.3 ± 3.2 Nm, p = 0.06), as shown in Figure 26C. All constructs failed due to a transverse fracture of the osteoporotic pedicle adjacent to the outermost screw hole.

0141Argument: The results of this biomechanical study show that the dynamic plate symmetrically enhances interskeletal motion to provide controlled axial dynamization while maintaining strength comparable to standard rock plate constructs. It became clear that it supports the inventor's hypothesis.

0142The finding that the axial stiffness of the dynamic plate is 77% lower than that of the standard plate is within 74-88% of the reported reduction in axial stiffness for DLS and FCL screws (Bottlang M, Feist F. "Far Cortex". Rock Biomechanics "J Orthop Trauma 2011; 25 Suppl 1: S21-8; Dobele S, Garder M, Schroter S, Hontzsch D, Stockle U, Freude T "DLS 5.0-Biomechanical Effects of Dynamic Lock Screws" PLoS One 2014; 9-4: e91933, and Doornink J, Fitzpatrick DC, Madey SM, Bottlang M. "Far cortex lock allows flexible fixation with a periarticular lock plate", J Orthop Trauma 2011; 25 Suppl 1: S29-34). However, unlike DLS and FCL screws, the elastic suspension of the screw holes provides a reduction in stiffness within the plate, which provides axial dynamization even when a short screw is needed to secure the plate of small diameter bone. Hold.

0143As the recognition that axial dynamization is essential to promote secondary bone healing has increased, several alternatives have been recommended to alleviate the inherent high stiffness of the lock plate construct. This includes the use of more flexible plates made of titanium rather than stainless steel and increased plate span by bridging the fracture zones with long sections of empty screw holes. Both of these strategies increase the amount of plate flexion in response to a given load, increasing movement in the distant cortex rather than the near cortex. The resulting asymmetric dynamization was confirmed in this biomechanical study, demonstrating that the axial dynamization evoked by a high standard construct load of about 1000 N in the near cortex is less than 0.2 mm. This is not enough to promote callus formation.

0144This biomechanical study also investigated the strength of dynamic constructs relative to standard constructs in both non-porosity and osteoporotic bones, as fixation strength and failure modes are greatly affected by bone quality. Testing to failure in both bone qualities for compression, twisting and bending demonstrated that the dynamic construct was at least as strong as or stronger than the standard construct. In the non-osteoporosis specimen, the dynamic construct had a twist strength 21% greater than the standard construct. This may be attributed to the loose staggering of the screw holes in the dynamic plate, which provides multi-planar stability under twist. Conversely, the standard plate had a standard linear hole pattern concentrated along the plane centerline, allowing a larger toggle of the elevated plate around a single fixed plane. This resulted in fatigue breakage of the screw shaft between the plate and the bone due to repeated bending of the screw shaft. This failure mode correlated with previous studies in which a lock plate was attached to the artificial femur at a height of 1 mm and failed in twisting as a result of screw breakage (Bottlang M, Doornink J, Fitzpatrick DC, Madey SM. "The far cortex lock can reduce the stiffness of the locked plate construct while preserving the strength of the construct," J Bone Joint Surg Am 2009; 91-8: 1985-94; and Stoffel. K, Booth G, Rohrl SM, Kuster M. "Comparison of conventional plates vs. lock plates in intra-articular heel fractures: biodynamic studies in human corpses", Clin Biomech (Bristol, Avon) 2007; 22-1: 100- Five). In the osteoporosis specimen, the dynamic construct showed 25% greater bending strength than the standard construct. Both constructs failed due to transverse breakage at the end of the plate. The bending strength of the dynamic structure superior to that of the standard structure is believed to be due to the elastic suspension of the lock holes inside the plate, which improves load distribution and reduces stress concentration and subsequent breakage at the plate edges.

0145The dynamic plate design is by embedding a separate sliding element with a locking hole inside a silicon elastomer enclosure that elastically suspends the locking hole inside the plate to prevent metal-metal contact between the sliding element and the plate. , Axial dynamization was obtained. Although the use of silicone elastomers appears to be novel in osteosynthesis implants, long-term implantable silicone has been used clinically for a range of permanent implants, such as knuckles. There is. Unlike silicone gels, the silicone elastomers used in the knuckles and the dynamic plates described herein are highly biocompatible and bioinert. With a wide range of priorities and a long clinical history of silicon elastomers, the new strategy allows the prerequisites for classical fracture healing to be incorporated into modern rock plates. That is, controlled axial dynamization promotes secondary bone healing.

0146In conclusion, this biomechanical study demonstrates that the dynamic lock plate symmetrically enhances interosseous motion, provides controlled axial dynamization, and is at least comparable to standard lock plate constructs in terms of strength. did. Since the dynamic lock plate can be attached with standard lock screws, it can provide a more scalable alternative to DLS and FCL screws for the dynamization of lock plate configurations.

0147Those skilled in the art will appreciate that the above embodiments can be modified without departing from the broad concept of the present invention. Specifically, the disclosed invention can be carried out for the fixation of the bone plate to only one side of the fracture and the corresponding side of the fractured bone by alternative means for flexible or firm fixation 1 Can be attached to one plate. Accordingly, this disclosure is not limited to the particular embodiments disclosed, but includes amendments within the spirit and scope of the present disclosure as defined by the claims.

0148An embodiment illustrated and described for a particular embodiment, but various other and / or equivalent embodiments or realizations devised to achieve the same purpose, without departing from the scope of the disclosure. Those skilled in the art should know that it can be replaced with a form. Those skilled in the art should readily appreciate that the embodiments can be implemented in a variety of ways. The present application is intended to cover any combination, adaptation or modification of the embodiments described above. Accordingly, embodiments are expressly intended to be limited only by claims and their equivalents.