Tensioning device

Abstract

The present disclosure relates to a tensioning device (1) for applying and maintaining a tension on at least one structure (2). The tensioning device (1) comprises a strip (3) extending in a longitudinal direction and comprising a backstop segment (51) and a pulley segment (61) arranged in longitudinal direction behind each other and each comprising at least one opening (71, 72, 73, 74, 75, 76). The tensioning device (1) further comprises at least a first filament (41) passing through the at least one opening (71, 72) of the backstop segment (51) and crossing itself at least once in the backstop segment (51) between the strip (3) and the first filament (41), thereby forming a self-locking backstop mechanism for preventing a tension applied to the first filament (41) from being released. The first filament (41) further passes through the at least one opening (73, 74) of the pulley segment (61), thereby forming at least one pulley loop (81, 82) extending from the pulley segment in a mounted position away from the backstop segment (51) and configured to encircle the structure (2) at least partially.

Description

[0001] Tensioning Device

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a tensioning device for applying and maintaining a tension on at least one structure, such as a biological structure.

[0004] BACKGROUND OF THE INVENTION

[0005] Several medical procedures require the application of tension to one or more biological structures. Once applied, the tension must be maintained to prevent loss of tension over time. An example are cerclage applications, which are surgical procedures in which a loop is placed around a structure, such as a vessel or bone, to provide support by constricting the loop and then maintaining the loop in a constricted state under tension. Other examples include anterior cruciate ligament (ACL) reconstruction surgery or posterior cruciate ligament (PCL) reconstruction, among many other surgeries, which may for example be performed on soft tissue or hard tissue. More broadly, many surgical operations require the approximation of two biological structures, such as the two ends of a torn tendon or ligament. For example, a surgical procedure to repair the torn tendon or ligament may involve connecting the two ends to a tensioning device to connect the two ends and restore tension. Typically, an implant is used to connect the two ends and a separate instrument is used to apply a tension force to the two torn ends. The prior art tension devices suffer from a number of disadvantages. For example, most known tensioning devices are specifically designed to either apply a tensioning force or to maintain a previously applied tension, but not both. In particular, many known devices for applying a tension force are not suitable for implantation in the body, in part because many have a complex mechanical structure which, while suitable for applying a tension force with high precision, is by its nature a surgical instrument rather than a biocompatible implant.

[0006] Another drawback is that many prior art devices are unable to establish a secure and firm connection and, more importantly, maintain tension over time. Once applied, a tension force typically decreases gradually over time with known tension devices. This severely limits their use, particularly in implantation cases where the tension force must be maintained over the course of months and years, if not decades.

[0007] Another disadvantage of known tensioning devices is the manual difficulty of applying tension, especially high tension, to a biological structure. For example, many known tension devices require a great deal of force to apply a high tension force to a biological structure. Applying a high force to the tension device during operation can be challenging and carries a risk of unintended damage, such as overload or unwanted or uncontrolled movement. In particular, to apply a given tensile force to a biological structure, many tension devices require the same tensile force to be applied by the surgeon (either manually or with mechanical assistance). Another drawback of many known tension devices is that they are difficult to perform, especially during complex procedures such as minimally invasive surgery. In addition, it is difficult to apply tension in a controlled manner with the known tensioning devices of the prior art. In particular, avoiding over- or under-tensioning is challenging. Finally, many of the known techniques are difficult and tedious for a surgeon to perform, thereby reducing efficiency.

[0008] Accordingly, there is a need for improved tension devices.

[0009] SUMMARY OF THE INVENTION

[0010] It is therefore an object of the present disclosure to advance the state of the art with respect to tensioning devices, particularly tensioning devices for applying and maintaining a tension on at least one structure, such as a biological structure. For example, it could be desirable to apply and maintain a tension on one structure or to apply and maintain a tension on two or more structures, for example between two structures. In particular, it is a further object to provide a tensioning device which allows maintaining a tension applied to the structure with minimal loss of tension over time. Ideally, the tension would remain essentially unchanged over the course of weeks, preferably over the course of months, more preferably over the course of years. It is a further object to provide a tensioning device which facilitates application of a tension on a structure such as a biological structure. In particular, it is an object of at least preferred variants that a tensile force applied by a user, for example by a surgeon in an operation, would be amplified. Ideally, the tensile force applied by a user would be amplified by at least 50%, preferably by a factor of at least 2. A further object of at least some variants of the device is to improve operability and to increase the ease of use of the device. Ideally, the device could be implanted and mounted in a minimally invasive surgery setting.

[0011] According to the present disclosure, these objects are addressed by the features of the independent claims. Further advantageous embodiments follow from the dependent claims and from the description.

[0012] The present disclosure relates in a first aspect to a tensioning device for applying and maintaining a tension on at least one structure. This structure could for example be a structure in a medical environment. The structure may e.g. be a biological structure.

[0013] The tensioning device comprises a strip extending in a longitudinal direction and comprising a backstop segment and a pulley segment. The backstop segment and the pulley segment are arranged in longitudinal direction behind each other and each comprise at least one opening. In some variants, the backstop segment comprises two or more openings, which are preferably arranged in longitudinal direction behind each other. Alternatively or in combination, the pulley segment may comprise two or more openings, which are preferably arranged in longitudinal direction behind each other.

[0014] The tensioning device further comprises at least a first filament. The first filament passes through the at least one opening of the backstop segment and crosses itself at least once in the backstop segment, thereby forming a self-locking backstop mechanism for preventing a tension applied to the first filament from being released. Typically, the first filament crosses itself at least once in the backstop segment between the strip and the first filament. In other words, when the first filament crosses itself, a section of the first filament is clamped between another section of the first filament and the strip.

[0015] The first filament further passes through the at least one opening of the pulley segment, thereby forming at least one pulley loop. The pulley loop extends from the pulley segment in a mounted position away from the backstop segment and is configured to encircle the structure at least partially.

[0016] Because the first filament crosses itself to form a self-locking backstop mechanism, loss of a tension previously applied on the structure is minimized. As an illustration, when a tensile force is applied in the first place, a first section of the first filament is crossed and clamped by second section of the first filament, such that the first section of the first filament is clamped between the second section of the first filament and the strip. This clamping force may be used to prevent displacement of the first filament, which would lead to loosening of the tension. Typically, a strip section with higher tension acts as a locking element for a strip section with lower tension. Additionally, the at least one pulley loop allows enhancement of the tensile force applied by a user, thereby facilitating application of high tensile forces on the structure.

[0017] In some variants, the tensioning device is configured such that the force applied to the structure is at least increased by a factor of 2 with respect to the force applied to the first filament. For example, when the pulley loop, which extends in the mounted position away from the backstop segment, is closed and in its circumference constricted during the process of applying a tensile force, the tensile force may be at least increased by a factor of 2 as a result of the mechanical principles of pulley systems. In particular, because the distance to be travelled in the case of one pulley loop have two opposing and adjacent sides has doubled, the factor of tensile force transmission is 2. Depending on the number of pulley loops, the factor by which the force applied to the structure is increased may be higher than 2. Typically, the tensioning device is configured such that the force applied to the structure is at least increased by a factor of 2n with respect to the force applied to the first filament, wherein n is an integer of 1 or higher, preferably from 1 to 20, more preferably from 1 to 12. It is understood that losses due to friction may occur, which may lead to slight deviations from a factor of precisely 2 or precisely 2n. Preferably, any losses e.g. due to friction or other factors do not exceed 25%, preferably do not exceed 10%, more preferably do not exceed 5%, with respect to the force applied to the first filament.

[0018] Depending on the application, the at least one pulley loop may be formed in different ways. For example, in some variants, the first filament passes through the at least one opening of the pulley segment, thereby forming the at least one pulley loop. The at least one pulley loop may be suitable to encircle the structure at least partially. The at least one pulley loop may for example extend in the longitudinal direction.

[0019] In some variants, the first filament successively passes through at least two openings of the pulley segment arranged in the longitudinal direction behind each other, thereby forming at least two pulley loops in a spiral shape manner. For example, a first pulley loop may be formed which is at least partially, preferably fully, encompassed by a second pulley loop. Optionally, there may for example be a third and more pulley loops, wherein the third pulley loop may at least partially, preferably fully, encompass the second pulley loop. Likewise, each subsequent pulley loop may at least partially, preferably fully, encompass each previous pulley loop. For example, the pulley loops may be arranged in a snail shell form. One advantage of these embodiments is that they allow a high factor of tensile force amplification, while minimizing friction. However, other arrangements are also possible. For example, the plurality of pulley loops may also be arranged adjacent to each other, independently of whether or not they encompass each other.

[0020] Depending on the application, the tensioning device may comprise one or more pulley loops. For example, the device may comprise two or more pulley loops, such as from two to six pulley loops.

[0021] Depending on the application, the first filament may pass through all or only some of the openings of the pulley segment. Further, the first filament may pass through each opening once of pulley segment once or multiple times. In some variants, the first filament passes through the at least one opening of the pulley segment once, i.e. only once. This may for example be advantageous to minimize friction. It is possible, for example, that the first filament passes through three of four openings in the pulley segment, and that the first filament passes through each of the three openings only once.

[0022] Depending on the application, the first filament may cross itself in the backstop section in different ways. For example, the first filament may in some variants form at least two crossings, preferably from two crossings to 30 crossings. Preferably at least one crossing is arranged on a first lateral side of the strip and at least one crossing is arranged on a second lateral side of the strip. For example, half of the crossings may be arranged on the first lateral side and half of the crossings may be arranged on the second lateral side. The number of crossings may for example be used to control and fine-tune the efficacy of the backstop mechanism.

[0023] In some variants, at least a section of the first filament extends helically around a lateral outer surface of the strip in the backstop segment. These variants may for example be used to optimize and fine-tune the backstop effect. For example, by extending helically around the lateral outer surface of the strip in the backstop segment, the respective section of the first filament may pass through backstop loops arranged on different lateral sides of the strip. In some variants, the section of the first filament passes through at least one backstop loop arranged on the first lateral side and through at least one backstop loop arranged on the second lateral side. For example, the section of the first filament may pass alternatingly through backstop loops (e.g. clamping loops) arranged on the first lateral side and on the second lateral side. Depending on the application, selected backstop loops may or may not be skipped. In some variants, the section of the first filament successively passes through openings arranged in the longitudinal direction behind each other.

[0024] In some variants, the one or more backstop loops may be labelled as one or more clamping loops. It is also possible that only some of the backstop loops act as clamping loops. In some variants, the first filament passes through the at least one opening of the backstop segment to form at least two backstop loops, wherein the first filament further passes through at least one of the at least two backstop loops. The at least two backstop loops extend laterally in a mounted position. Depending on the application, the first filament may pass through all backstop loops, or only through some of the backstop loops. There may be two or more backstop loops, for example in some variants at least four backstop loops are formed. Depending on the application, the at least two backstop loops may have different arrangements. For example, at least one backstop loop may be arranged on a first lateral side of the strip and at least one backstop loop may be arranged on a second lateral side of the strip opposite the first lateral side. In some variants, for each backstop loop a filament section forming the respective backstop loop exits and enters the same or a different opening. Alternatively or in combination, for each backstop loop, a filament section forming the respective backstop loop may exit and enter the respective opening on the same or on opposite lateral sides of the strip. In some variants, each backstop loop is formed between two different openings.

[0025] In some variants, the first filament passes through at least two openings of the backstop segment arranged in longitudinal direction behind each other in a meandering manner. These variants may for example be used to facilitate preparation of the tensioning device. Further, the arrangement in a meandering manner may for example be used to allow homogeneous distribution of a clamping force applied by the backstop loops. In some variants, the first end of the first filament is fixedly connected to the strip. For example, the first end of the first filament may be knotted to the strip. The first end of the first filament may for example be fixedly connected to the strip at a connection position of the strip. The connection position may for example be arranged in the pulley segment of the strip. For example, the connection position may be arranged in the pulley segment and facing in longitudinal direction away from the backstop segment. As an example, the connection position may be arranged near or at a second end of the pulley segment arranged in the longitudinal direction opposite a first end of the pulley segment, which first end of the pulley segment faces towards the backstop segment.

[0026] A second end of the first filament may for example be loose or free. For example, the second end may be loose in order to apply a tension to the first filament, e.g. by pulling the second end.

[0027] Depending on the application, the tensioning device may comprise more than one backstop segment. Alternatively or in combination, the tensioning device may comprise more than one pulley segment. Alternatively or in combination, the tensioning device may comprise a second filament. In these variants, the backstop segment and the pulley segment described hereinbefore and hereinafter may for example be labelled as first backstop segment and first pulley segment, respectively. In other words, for variants featuring a “second backstop segment”, the “backstop segment” not being the “second backstop segment” may optionally be labelled as “first backstop segment” in order to distinguish it more clearly from the “second backstop segment”. Similarly, for variants featuring a “second pulley segment”, the “pulley segment” not being the “second pulley segment” may optionally be labelled as “first pulley segment” in order to distinguish it more clearly from the “second pulley segment”. The embodiments described herein in the context of the backstop segment in general may apply to the first backstop segment, or they may apply to the first and second backstop segment. Similarly, the embodiments described herein in the context of the pulley segment in general may apply to the first pulley segment, or they may apply to the first and second pulley segment.

[0028] In some variants, the first backstop segment, the first pulley segment and the second backstop segment and / or the second pulley segment are arranged in the longitudinal direction behind each other and each comprise at least one opening.

[0029] In some variants, the tensioning device further comprises a second filament passing through the at least one opening of the second backstop segment and crossing itself at least once in the second backstop segment between the strip and the second filament, thereby forming a second self-locking backstop mechanism for preventing a tension applied to the second filament from being released. The embodiments described herein in the context of the self-locking backstop mechanism may apply to both the first self-locking backstop mechanism and, independently of the first self-locking backstop mechanism, also to the second selflocking backstop mechanism.

[0030] Alternatively or in combination, the second filament may further pass through the at least one opening of the second pulley segment, thereby forming at least one pulley loop extending from the second pulley segment in a mounted position away from the second backstop segment. The at least one pulley loop is typically configured to encircle the structure at least partially. For example, the at least one pulley loop may be suitable to encompass at least a circumferential segment of the structure.

[0031] Depending on the application, the pulley segments and the backstop segments may have different arrangements with respect to each other. For example, the backstop segment and the second backstop segment may both be arranged in longitudinal direction between the pulley segment and the second pulley segment.

[0032] Depending on the application, different strips may be used. In some variants, strip is at least partially made from a braided material. Alternatively or in combination, the strip may be made from a resorbable material. Depending on the application, the strip may for example have a length of up to 500 mm, preferably up to 200 mm, more preferably from 1 mm to 100 mm. For example, in some variants, the strip has a length from 5 mm to 80 mm. Depending on the application, the strip may have different shapes and geometry. For example, in some variants, the strip may be ladder-shaped. The strip may be made out of different materials, for example, it may be made out of a flexible material. In some variants, the strip is compressible in longitudinal direction. Alternatively or in combination, the strip may be compressible in radial direction.

[0033] The openings of the strip may in some variants for example be eyelets. Depending on the application, the openings may extend with respect to the longitudinal direction transversally from a first lateral side of the strip to an opposite second lateral side of the strip. Depending on the application, the first lateral side and the second lateral side may be arranged parallel to each other. In some variants, a central axis of each opening of the strip is parallel to the central axis of each other opening of the strip.

[0034] In some variants, the strip is designed compressible in the longitudinal direction such that when a tensile force is applied on the first filament the distance between the at least two openings in longitudinal direction is reduced.

[0035] The material of the first filament and the material of the strip may be chosen such that a suitable compromise between gliding properties and friction is achieved. For example, in some variants, the first filament and / or the second filament and / or any further filaments are made of a material having a surface with a low friction coefficient. In some variants, the first filament and the strip are configured to allow smooth gliding of the first filament through the openings of the strip.

[0036] Depending on the application, different filaments may be used. For example, the first filament may be a suture, such as a medical suture. Different materials may be envisaged. Typically, the filament is made from a material having a surface with a low friction coefficient. In some variants, the filament is made from a material having a surface with a friction coefficient similar to a friction coefficient of the at least one filament. Depending on the application, the filament may for example have a cross section of less than 100 mm2, preferably less than 25 mm2.

[0037] In some variants, the tensioning device comprises at least one removable application aid forming an open space in at least one backstop loop (e.g. in at least one backstop loop). The section of the first filament passing through the at least one backstop loop may for example pass through the application aid. Depending on the application, the tensioning device may be used for applying and maintaining a tension on one or more structures, for example one or more biological structures. For example, a first structure may be interconnected with a first end of the strip and a second structure maybe interconnected with a second end of the strip, wherein the second end is arranged opposite in longitudinal direction to the first end of the strip. In this example, the tensioning device may be used to approximate the first biological structure and a second biological structure. In another example, the tensioning device may be used for cerclage applications. For example, in a mounted position, the tensioning device may encircle a biological structure. To this end, for example, the at least one pulley loop may in a mounted position be interconnected with an end of the strip which is arranged opposite the at least one pulley loop.

[0038] In some variants, the tensioning device further comprises a first interface for interconnecting the strip to a structure and / or to the at least one pulley loop. Depending on the application, the first interface may in the mounted position directly or indirectly interconnect the strip to the structure and / or the at least one pulley loop. In some variants, the tensioning device further comprises a third filament interconnecting in a mounted position the at least one pulley loop and the first interface.

[0039] Depending on the application, the first interface may be arranged in different parts or segments of the strip. For example, in some variants, the first interface is arranged in an interface segment, which may e.g. be labelled as fixation segment. In some variants, the interface segment, the backstop segment and the pulley segment are arranged in longitudinal direction behind each other, in particular adjacent to each other. In some variants, the backstop segment is arranged in longitudinal direction between the interface segment and the pulley segment. If there are two or more backstop segments, the first backstop segment may in some variants be arranged in the longitudinal direction between the interface segment and the pulley segment. Alternatively or in combination, if there are two or more pulley segments, the backstop segment may in some variants be arranged in the longitudinal direction between the interface segment and the first pulley segment.

[0040] Depending on the application, different embodiments are possible to realize the first interface. For example, the first interface may comprise an opening of the strip. In this example, the third filament may for example be knotted to that opening. In some variants, the first interface comprises a backstop segment, which may either be the same backstop segment as previously described, or which may be a separate backstop segment. For example, the interface may comprise a third backstop segment, wherein the first backstop segment may be arranged in longitudinal direction between the third backstop segment and the pulley segment. It is understood that the term “third” is used merely to distinguish the different backstop segments, but that it does not necessarily imply that there are at least three backstop segments. In other words, in these variants, the tensioning device may or may not comprise a second backstop segment. The third backstop segment may for example be configured to receive and clamp the at least one pulley loop. Alternatively or in combination, the third backstop segment may for example be configured to receive and clamp the third filament. As an example, the third backstop segment may comprise at least one backstop loop, which may in the mounted state extend laterally from the strip. The at least one backstop loop of the third backstop segment may be configured to receive and clamp in the mounted position the third ligament. Alternatively or in combina- tion, the at least one backstop loop of the third backstop segment may be configured to receive and clamp in the mounted position the at least one pulley loop.

[0041] The first interface may for example be arranged at an end of the strip which is arranged opposite the at least one pulley loop.

[0042] In some variants, the first interface comprises a retention element and the third ligament comprises a bulge configured to be received by the retention element.

[0043] As an example, the retention element may be an eyelet having a maximum inner extension that is smaller than a maximum outer extension of the bulge. For example, when a tensile force is applied, the bulge may be held back by the retention element, such that a tension may be applied to the structure. The tensioning device described herein may be used for different applications, including in the medical field. The applications include, but are not limited to: cerclage systems, Trochanter-Reposition-Fixation, Sternum Closure, Spinal-Applications such as posterior fixations around spinal processes, ACL, PCL, AC-Joint, and Syndesmosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The invention described herein will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The drawings are showing:

[0045] Fig. 1 an embodiment of the tensioning device;

[0046] Fig. 2 a further embodiment of the tensioning device in a cerclage application and including a third filament;

[0047] Fig. 3 a further embodiment of the tensioning device in a further cerclage application;

[0048] Fig. 4 a further embodiment of the tensioning device in a further cerclage application and including a second backstop segment;

[0049] Fig. 5 a further embodiment of the tensioning device in a further cerclage application and including a second backstop segment and a second pulley segment;

[0050] Fig. 6 an embodiment of the tensioning device in an application for applying and maintaining a tension between two biological structures. DESCRIPTION OF THE EMBODIMENTS

[0051] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0052] Figure 1 shows an embodiment of a tensioning device 1. The tensioning device 1 comprises a strip 3 extending along a longitudinal axis. The tensioning device 1 further comprises a filament 41 , for example a suture. A first end of the filament 41 is knotted to an opening 74 of the strip 3. A second end of the filament 41 is loose and may be pulled by a user to apply a tensile force.

[0053] The strip 3 comprises a backstop segment 51 and a pulley segment 52, which is arranged in longitudinal direction behind the backstop segment 51 . The backstop segment 51 comprises multiple openings 71 , 72, which are also arranged in longitudinal direction behind each other. As illustrated, the openings 71 , 72, 73, 74 of the strip may in some variants be arranged centrally with respect to the longitudinal direction. Starting from its knotted first end, the filament 41 extends in longitudinal direction away from the backstop segment 51 , before it returns towards the backstop segment 51 and enters into an opening 73 of the pulley segment 61 , thereby forming a first pulley loop 81 . The pulley loop 81 may be described to extend in lateral direction away from the backstop segment 51 . A second pulley loop 82 is formed in a similar fashion, as illustrated in figure 1 . In the illustrated embodiment, the pulley loops 81 , 82 are arranged in a spiral shape manner. However, different arrangements are conceivable as well.

[0054] In the backstop segment 51 , the first filament 41 passes consecutively through openings 71 , 72 of the strip 3, thereby forming a plurality of backstop loops 91 , 92 on either lateral side of the strip 3. In the illustrated embodiment, each backstop loop 91 , 92 is formed between two adjacent openings. After reaching an opening 71 of the backstop segment 51 , which is arranged opposite the pulley segment 61 , the first filament 41 returns in longitudinal direction towards the pulley segment 61. On returning, the first filament 41 passes through the laterally extending backstop loops 91 , 92. As the backstop loops 91 , 92 are arranged al- ternatingly on opposite lateral sides of the strip 3, the first filament 41 passes helically around lateral outer surface of the strip 3. Though in the illustrated embodiment, the first filament 41 passes through all backstop loops 91 , 92, it is also possible that the first filament 41 passes only through a portion of the backstop loops 91 , 92. Preferably, the first filament 41 passes through at least two, more preferably through at least three backstop loops 91 , 92.

[0055] Eventually, the first filament 41 reaches its loose end, which may be pulled in order to apply a tension, as further illustrated in figure 2.

[0056] Figure 2 shows a further embodiment of the tensioning device 1 . The tensioning device 1 illustrated in figure 2 is similar to the tensioning device 1 illustrated in figure 1 , but additionally includes a third filament 43 and also illustrates a cerclage application, as illustrated by biological structure 2. The third filament 43 passes through the pulley loops 81 , 82 and is wrapped around the biological structure 2, before being connected to opening 71 of the strip 3, for example using a cow hitch.

[0057] In order to tighten the cerclage by applying a tensile force, the two loose ends of the third filament 43 are initially connected to each other, for example by knotting. Subsequently, the tensile force is applied by pulling the loose end of the first filament 41 . Upon pulling the loose end of the first filament 41 , the pulley loops 81 , 82 and the backstop loops 91 , 92 are increasingly constricted. Constriction of the pulley loops 81 , 82 reduces the longitudinal extension of the respective pulley loop 81 , 82, thereby increasingly constricting the biological structure 2. Because the tensioning device 1 comprises two backstop loops 91 , 92, each of which include two opposite portions extending in longitudinal direction, the overall factor of force transmission is 4. In other words, a tensile force applied, e.g. by a surgeon, on the loose end of the first filament 41 , is effectively increased by a factor of 4, such that a significantly stronger tensile force may be applied to the biological structure 2. It is understood that friction and other effects may lead to slight deviations from the theoretical factor of force transmission of 4.

[0058] At the same time, the backstop loops 91 , 92 are increasingly constricted, thereby clamping the filament 41 between the respective backstop loop 91 , 92 and the strip 3. This clamping prevents displacement of the first filament 41 , thereby effectively maintaining the tensile force applied.

[0059] In the illustrated embodiment, the strip 3 is made of a braided material and comprises a plurality of bifurcation sections, which define the openings. Further, in the illustrated embodiment, the strip 3 has an oval cross-section. However, other materials and other cross sections may be used as well.

[0060] Figure 3 illustrates a further embodiment of the tensioning device 1 , which is similar to the embodiment shown in figure 2, but features a further variant of an interface to connect the third filament 43 with the strip 3. Specifically, in the embodiment illustrated in figure 3, the third filament 43 comprises a bulge 11 , which may e.g. be formed by a knot. The diameter of the bulge is chosen to be larger than an inner diameter of a receiving loop 10, which forms the first interface 10 of the strip 3. This receiving loop 10 is arranged in longitudinal direction opposite the pulley segment 61. Though not illustrated in figure 3, the receiving loop 10 may be designed to be self-constricting. Because in a mounted state, the inner diameter of the receiving loop 10 is smaller than the diameter of the bulge of the third filament 43, once the bulge of the first filament 43 has been passed through the receiving loop 10, it is held back by the receiving loop 10 on application of a tensile force on the loose end of the first filament 41 , thereby allowing a tensile force to be applied on the biological structure 2.

[0061] Figure 3 further illustrates that an auxiliary stabilizing structure may be used to apply a counter-force to the strip 3 during application of the tension. The auxiliary stabilizing structure may for example be passed through one for the openings of the strip 3, for example through the second-to-last opening, as illustrated in figure 3.

[0062] Figure 4 illustrates yet another variant of the first interface 10, which involves the use of a second backstop segment 52 as first interface 10 for receiving and fixing the third filament 43. Specifically, the first backstop segment 51 is arranged in longitudinal direction between the second backstop segment 52 and the pulley segment 61 . The second backstop segment 52 comprises six openings 75, which are arranged in longitudinal direction behind each other. A first end of the third filament 43 is fixedly connected to the strip 3, for example by being knotted to one of the openings. Subsequently, the third filament 43 forms a plurality of backstop loops of the second backstop segment 52, before being circumferentially passed around the biological structure 2 to be tensioned, and subsequently passing through the pulley loops 81 , 82 of the pulley segment 61 . Subsequently, the third filament 43 is passed circumferentially around the biological structure 2 again and returns to the second backstop segment 52, where the third filament 43 passes through at least some of the backstop loops of the second backstop segment 52. In the illustrated embodiment, the third filament 43 passes through three backstop loops of the second backstop segment 52, but other variants are possible as well.

[0063] In the embodiment illustrated in figure 4, the tensile forces are applied by pulling the loose ends of both the first filament 41 and the third filament 43. This leads to increasing constriction of the pulley loops 81 , 81 of the pulley segment 61 , of the backstop loops 91 , 92 of the first backstop segment 51 , and of the backstop loops of the second backstop segment 52. Constriction of the backstop loops of the second backstop segment 52 leads to clamping of the third filament 43 between the backstop loops of the second backstop segment 52 and the strip 3, thereby preventing displacement of the third filament 43, thereby preventing loosening of the applied tensile force. Figure 4 further illustrates that the tensioning device 1 may comprise an application aid as part of the first interface 10. Specifically, the application aid may comprise a tube passing through the backstop loops through which the third filament 43 passes and facilitates passing the third filament 43 through these backstop loops and keeps the third filament 43 in place.

[0064] Figure 5 illustrates an embodiment of the tensioning device 1 comprising two backstop segments 51 , 52 and two pulley segments 61 , 62. The two backstop segments 51 , 52 are arranged in longitudinal direction between the two pulley segments 61 , 62. A first filament 41 passes through the openings 71 , 72, 73, 74 of the first backstop segment 51 and of the first pulley segment 61 , as described e.g. in the context of figure 1 above. Similarly, a second filament 42 passes through the openings 75, 76 of the second backstop segment 52 and of the second pulley segment 62. The two sides may, but do not have to be, mirror symmetrical. The pulley loop 81 of the first pulley segment 61 is interconnected with the pulley loop 83 of the second pulley segment 62 by a third filament 43. The two loose ends of the third filament 43 may e.g. be knotted together, as illustrated in figure 5. Application of the tensile force on biological structure to involves pulling of the loose end of the first filament 41 , and of the loose end of the second filament 42.

[0065] Figure 6 illustrates an embodiment of the tensioning device 1 in an application for applying and maintaining a tension between two biological structures. The structure of the tensioning device 1 is similar to the embodiment illustrated in figure 1 in that it also comprises a strip 3 having a pulley segment 61 and a backstop segment 51 , as well as a first filament 41 forming pulley loops 81 , 82 and backstop loops 91 , 92.

[0066] The embodiment of figure 6 additionally comprises a first interface 10. Similar to the auxiliary stabilizing structure illustrated in the context of figure 3, the first interface 10 of the embodiment shown in figure 6 is interconnected to an auxiliary stabilizing structure, which may e.g. be used to apply a counter-force to the strip 3 during application of a tension. Figure 6 further illustrates that the pulley loops 81 , 82 are interconnected to a first biological structure 2. Thus, the pulley loops 81 , 82 may effectively act as a second interface for interconnecting the tensioning device 1 to the first biological structure 2. The first biological structure 2 may for example be a graft to which a tension is to be applied.

[0067] Different applications are conceivable using the embodiment illustrated in figure 6. For example, the tensioning device 1 may be used to apply a tension to the first biological structure 2 (e.g. a graft). In this variant, the auxiliary stabilizing structure may be used essentially for applying a counter-force during application of the tension on the first biological structure 2. In use, pulling of the loose end of the first filament 41 will, as explain above, lead to increasing constriction of the pulley loops 81 , 82, which leads to increasing tensioning of the second biological structure 2 towards the first interface 10. In further variants, the strip 3 may additionally be interconnected to a second biological structure. The second biological structure may for example be passed through the opening acting as first interface 10, for example instead of or in addition to an auxiliary stabilizing structure. For example, instead of being understood to be the auxiliary stabilizing structure, the longitudinal structure passing through the opening acting as first interface 10 in figure 6 may in some variants be understood to be a second biological structure. In this variant, the tensioning device 1 may be used to apply and maintain a tension between said second biological structure and the first biological structure 2. In still further variants, the auxiliary stabilizing structure may be used not instead of, but rather in addition to a second biological structure. The second biological structure may for example be interconnected to the strip 3 in other ways, e.g. using another interface. For example, the strip 3 may additionally comprise a second backstop segment (not illustrated) for the purposes of being interconnected to the second biological structure. Said second backstop segment may for example be arranged in longitudinal direction of the strip 3 adjacent to the first interface 10. As an example, the first interface 10 may in longitudinal direction be arranged between the first backstop segment 51 (illustrated in figure 6) and a second backstop segment (not illustrated in figure 6), wherein the second backstop segment may be used for being interconnected to the second biological structure. In these variants, the tensioning device 1 may be used to apply and maintain a tension between a first biological structure 2 and a second biological structure.

[0068] LIST OF DESIGNATIONS

[0069] Tensioning device

[0070] 2 structure

[0071] 3 strip 41 first filament

[0072] 42 second filament

[0073] 43 third filament

[0074] 51 first backstop segment

[0075] 52 second backstop segment 61 first pulley segment

[0076] 62 second pulley segment

[0077] 71 ,72,73,74,75,76 openings of the strip

[0078] 81 ,82,83,84 pulley loops

[0079] 91 ,92 backstop loops 10 first interface

[0080] 11 bulge

Claims

PATENT CLAIMS1 . Tensioning device (1 ) for applying and maintaining a tension on at least one structure (2), comprising: a. a strip (3) extending in a longitudinal direction and comprising a backstop segment (51 ) and a pulley segment (61 ) arranged in longitudinal direction behind each other and each comprising at least one opening (71 , 72, 73, 74, 75, 76); b. at least a first filament (41 ) passing through the at least one opening (71 , 72) of the backstop segment (51 ) and crossing itself at least once in the backstop segment (51 ) between the strip (3) and the first filament (41 ), thereby forming a self-locking backstop mechanism for preventing a tension applied to the first filament (41 ) from being released; c. wherein the first filament (41 ) further passes through the at least one opening (73, 74) of the pulley segment (61 ), thereby forming at least one pulley loop (81 , 82) extending from the pulley segment in a mounted position away from the backstop segment (51 ) and configured to encircle the structure (2) at least partially.

2. Tensioning device (1 ) according to claim 1 , wherein the tensioning device (1 ) is configured such that the force applied to the structure (2) is at least increased by a factor of 2 with respect to the force applied to the first filament3. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament (41 ) passes through the at least one opening (73, 74) of the pulley segment (61 ), thereby forming the at least one pulley loop (81 , 82), suitable to encircle the structure (2) at least partially.

4. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament (41 ) passes through the at least one opening (71 , 72) of the backstop segment (51 ) to form at least two in the mounted position laterally extending backstop loops (91 , 92), wherein the first filament (41 ) further passes through at least one of the at least two backstop loops (91 , 92).

5. Tensioning device (1 ) according to any one of the previous claims, wherein for each backstop loop (91 , 92) a filament section forming the respective backstop loop (91 , 92) exits and enters the same or a different opening on the same or on opposite lateral sides of the strip (3).

6. Tensioning device (1 ) according to any one of the previous claims, wherein each backstop loop (91 , 92) is formed between two different openings (71 , 72, 73, 74, 75, 76).

7. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament (41 ) passes through at least two openings (71 , 72) of the backstop segment (51 ) arranged in longitudinal direction behind each other in a meandering manner.

8. Tensioning device (1 ) according to any one of the previous claims, wherein at least a section of the first filament (41 ) extends helically around a lateral outer surface of the strip (3) in the backstop segment (51 ).

9. Tensioning device (1 ) according to any one of the previous claims, wherein a first end of the first filament (41 ) is fixedly connected to the strip (3).

10. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament (41 ) successively passes through at least two openings (73, 74) of the pulley segment (61 ) arranged in the longitudinal direction behind each other, thereby forming at least two pulley loops (81 , 82) in a spiral shape manner.1 1 . Tensioning device (1 ) according to any one of the previous claims, further comprising: a. a second backstop segment (52) and / or a second pulley segment (62), wherein the backstop segment (51 ), the pulley segment (61 ) and the second backstop segment (52) and / or the second pulley segment (62) are arranged in the longitudinal direction behind each other and each comprise at least one opening (71 , 72, 73, 74, 75, 76); and b. a second filament (42), i. wherein the second filament (42) passes through the at least one opening of the second backstop segment (52) andcrosses itself at least once in the second backstop segment (52) between the strip (3) and the second filament (42), thereby forming a second self-locking backstop mechanism for preventing a tension applied to the second filament (42) from being released; ii. and / or wherein the second filament (42) further passes through the at least one opening of the second pulley segment, thereby forming at least one pulley loop (83, 84) extending from the second pulley segment (62) in a mounted position away from the second backstop segment (52) and configured to encircle the structure (2) at least partially.

12. Tensioning device (1 ) according to claim 1 1 , wherein the backstop segment (51 ) and the second backstop segment (52) are both arranged in longitudinal direction between the pulley segment (61 ) and the second pulley segment (62).

13. Tensioning device (1 ) according to any one of the previous claims, wherein the strip (3) is designed compressible in the longitudinal direction such that when a tensile force is applied on the first filament (41 ) the distance between the at least two openings (71 , 72, 73, 74, 75, 76) in longitudinal direction is reduced.

14. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament (41 ) passes through the at least one opening (73, 74) of the pulley segment (61 ) once.

15. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament and the strip (3) are configured to allow smooth gliding of the first filament (41 ) through the openings of the strip (3).

16. Tensioning device (1 ) according to any one of the previous claims, wherein the first filament (41 ) is made of a material having a surface with a low friction coefficient.

17. Tensioning device (1 ) according to any one of the previous claims, wherein the strip (3) is at least partially made from a braided material.

18. Tensioning device (1 ) according to any one of the previous claims, wherein the strip (3) is made from a resorbable material.

19. Tensioning device (1 ) according to any one of the previous claims, further comprising a first interface (10) for interconnecting the strip (3) to a structure (2) and / or to the at least one pulley loop (81 , 82).

20. Tensioning device (1 ) according to claim 19, further comprising a third filament (43) for interconnecting in a mounted position the at least one pulley loop (81 , 82) and the first interface (10).

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