Patent Publication Number: US-2021162208-A1

Title: Device for extravasal or extraneuronal fastening of a medical implant in the manner of a compression sleeve

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     REFERENCE IS MADE TO PCT/EP2019/061599 FILED MAY 7, 2019, DESIGNATING THE UNITED STATES, WHICH CLAIMS PRIORITY TO GERMAN APPLICATION NO. 10 2018 207 709.6 FILED MAY 17, 2018, WHICH ARE INCORPORATED HEREIN BY REFERENCE IN THEIR ENTIRETY 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a device for the extravasal or extraneuronal fastening of a medical implant with a biocompatible surface substrate having a first substrate portion which is configured as a compression sleeve and has a free end portion, which by winding the first substrate portion about a spatial axis, is loosely radially covered in at least layer by the wound first substrate portion, and also second substrate portion, which is attached integrally to the first substrate portion, is not wound about the spatial axis, and is connectable directly or indirectly to a connection structure leading away from the medical implant. 
     Description of the Prior Art 
     A medical implant of this type, configured in the manner of a compression sleeve for detection as well as application of neuronal electrical signals for permanent or at least long-term positioning along a nerve fiber bundle within the human or animal body is described in WO 2016/055512 A1 and is also shown schematically in  FIG. 2 . The medical implant  1 , made of a biocompatible surface substrate  2  and configured as a compression sleeve, comprises a first substrate portion  3  which is wound about a spatial axis  5  forming at least one surface substrate winding which radially surrounds a straight cylindrical hollow space H. Attached on the surface substrate surface facing the straight cylindrical hollow space H are electrode surfaces, (not shown in  FIG. 2 ); which come into physical contact with the epineurium of a nerve fiber bundle encompassed by the compression sleeve  1 , which is also not shown in  FIG. 2 . In order to guarantee that on the one hand the medical implant  1  remains as fixed in place as possible along a nerve fiber bundle after appropriate implantation, and on the other hand can follow the natural changes in shape of the nerve fiber bundle or at least is not subject to any significant mechanical resistance, the individual surface substrate windings loosely adjoin each other and in the event of expansion of the nerve fiber bundle, increase the diameter of the encompassed hollow space H through appropriate relative movement. 
     Through material pre-tensioning applied to the surface substrate  2  in the first substrate portion  3 , the surface substrate  2  takes on a predefined winding configuration without the effect of external forces, in which the free portion end  4  is at least loosely radially covered in one layer by the first substrate portion, that is by at least one surface substrate winding. 
     Adjoining the wound first substrate portion  3  in one piece, and not wound about the spatial axis  5  is a second substrate portion  6 , within which there are electrical leads that are connected to the plurality of electrodes coming into contact with the epineurium of the nerve fiber bundle. In the illustrated example embodiment, the also flat second substrate portion  6  comprises a web-like surface portion  6  orientated in parallel to the spatial axis  5 , which via an interface S, not illustrated, in the form of an implantable plug connection for example, is connected to a connection structure  7  leading away from the medical implant  1  along which the electrical leads extend to a separate, preferably implantable unit. 
     In an unstressed state, the mechanical implant  1  lies along a nerve fiber bundle N in accordance with the schematic view in  FIG. 3 a    uniformly enclosing diametrically the first substrate portion  3  to form a compression sleeve. In this state, none or only a minimal mechanical eternal force acts on the nerve fiber bundle N. If, on the other hand, external forces F act on the medical implant  1  which originate, for example, as shown from the body&#39;s own movements, deformations of the winding geometry can occur along the first substrate portion  3  configured as a compression sleeve, through which the fastening of the medical implant along the nerve fiber bundle N can no longer be guaranteed, and, on the other hand, a mechanical stress can act on the nerve fiber bundle through the medical implant. Such stress situations are shown in  FIGS. 3 b   ) to e). Thus, for example, tensile forces F, which are essentially orientated in parallel to the longitudinal extension of the nerve fiber bundle N, result in a funnel-shaped deformation within the compression sleeve, which on the one hand leads to a constriction E on nerve fiber bundle N, and on the other hand to a widening A, and associated radial extension of the compression sleeve from nerve fiber bundle N, as seen in  FIGS. 3 b   ) and  c ). Constriction E of the nerve fiber bundle N can also occur in the case of a force F, orientated orthogonally to the longitudinal extension of the nerve fiber bundle, acting on the medical implant  1 , see the stress situation as illustrated in  FIG. 3 d   ). In this case the force F as a tensile force acts transversely to the nerve fiber bundle N. In  FIG. 1 e   ) the force acts in the opposite force direction as a thrust force directed onto the nerve fiber bundle N, through which the compression sleeve widens in diameter and tends to become detached from the nerve fiber bundle N. 
     A cuff electrode in an original form is set out in DE 44 33 111 A1 and has an interdigital surface form, with individual finger portions opening outward depending on external pressure and force exertions. 
     U.S. Pat. No. 4,602,624 discloses an implantable cuff electrode with a surface substrate which winds itself into a hollow cylindrical shape and has different internal diameters in the axial longitudinal extension. The hollow cylindrical shape is solely maintained by inherent material predetermined pre-tensioning. 
     WO 2013/150524 A1 discloses an electrode cuff arrangement with a series of individual metal cuffs serving as electrodes, which are all radially encompassed from outside by a metal housing, which can be transformed from an open into a closed state in which the latter is secured by a locking clip mechanism. 
     SUMMARY OF THE INVENTION 
     The invention is a device for extravasal or extraneuronal fastening of a medical implant with a biocompatible surface substrate having a first substrate portion, which is configured as a compression sleeve and has a free end portion, which by winding the first substrate portion about a spatial axis, is loosely radially covered in at least a layer by the wound first substrate portion, and also has second substrate portion, which is attached integrally to the first substrate portion, is not wound about the spatial axis, and is connectable directly or indirectly to a connection structure leading away from the medical implant. Thus a secure and at the same time protected and durable application of the medical implant along an intracorporeal vessel or nerve fiber bundle is obtained. The measures to be taken should avoid movement-related deformations of the compression sleeve, or at least reduce them to such a degree that no appreciable mechanical stresses are exerted on the intracorporeal vessel of nerve fiber bundle. For the operator, the measures to be taken should not represent appreciable additional effort in terms of time or manipulation during the implantation. 
     In accordance with the invention, a device for the extravasal or extraneuronal fastening of a medical implant with a biocompatible surface substrate having a first substrate portion, configured as a compression sleeve, is characterised in the region of the end portion of the first substate portion configured as a compression sleeve, has at least one attachment applied thereto, which in the wound state of the first substrate portion about the spatial axis forms a joint connection with at least one of the first substrate portion and the second substrate portion being spatially separated from the portion end. 
     According to the invention, the end at the free portion of the first substrate portion which is configured as a compression sleeve, is detachably firmly connected which by the attachment to transmit at least one tensile force to an area of the carrier substrate which is preferably located within the second substrate area, which is the area of the carrier substrate that integrally adjoins the first substrate portion of the compression sleeve. The at least one attachment is arranged and designed so that in the case of an external force acting on the medical implant, a stopping or supporting force is produced through which the form and shape of the compression sleeve remains unchanged. The at least one attachment can primarily transmit tensile force between the free portion end and the join area. In principle it is also possible to provide a joint connection area within the first substrate portion, but in this case it must be ensured that between the area of the portion end on which the attachment is applied, and the joint connection at least one complete winding of the first sustrate portion extends about the spatial axis. 
     In a preferred embodiment, the at least one attachment is a flexible and non-stretchable strand of material, preferably in the form of a thread or strip. In each case, the strand of material is firmly attached by its two ends in the region of the end of the first substate portion or is integrally connected thereto. The other end of the strand of material is fastened in the area of at least one of the first and second substrate portion by a detachable firm joint connection, preferably as at least one of a frictional and interlocking connection. Advantageously, for this, in the area of at least one of the first and second substrate portion the biocompatible surface substrate has at least one fastening opening, completely passing through the surface substrate, through which the strand of material can be threaded for the purpose of providing a detachable firm connection, preferably for forming a knot. 
     In a preferred embodiment, the at least one attachment is designed as a tab which laterally projects beyond the first substrate portion in the area of the end if the portion and is connected thereto in one piece. Provided along the first or second substrate portion is a slit-shaped recess into which the tab can be introduced, forming a frictional and/or interlocking joint connection. Here, preferably the slit-shaped recess is located within an area of the first or second substrate portion which projects beyond the first substrate portion configured as a compression sleeve in the longitudinal extension of the winding. A more detailed explanation of this is set out in the following description with reference to a concrete example of embodiment. 
     Fundamentally, the first substrate portion has a longitudinal winding extension orientated about the spatial axis as well as a longitudinal cuff extension orientated axially to the spatial axis, wherein the longitudinal winding extension is determined by the distance between the free end portion and the second substrate portion adjoining the first substrate portion. In a preferred embodiment, the longitudinal cuff extension tapers within the first substrate portion as the distance increases to the end of the portion in a stepwise manner, preferably evenly along the winding extension. Through this, the opposite ends of the portion end in the wound form of the first substrate portion axially remain freely accessible from outside, so that the strand of material can extent to the joint area without being hindered by each of the opposite ends of the portion end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other aspects and features in accordance with the invention are set out in the further description with reference to the drawings. 
       As an example, the invention will be described below, without restricting the general inventive concept, by way of examples of embodiment with reference to the drawings. Here: 
         FIG. 1 a   ) shows an example of an embodiment according to the invention with a single connection; 
         FIG. 1 b   ),  c ) show examples of an embodiment of the invention each with two connections; 
         FIG. 2 ) shows a medical implant with a compression sleeve in accordance with prior art; 
         FIG. 3 a   )- e ) show various stress states of a medical implant formed as a compression sleeve; 
         FIG. 4 a   ),  c ) shows an example of an embodiment according to the invention with bilateral tab fastening; and 
         FIG. 5 a   ),  b ) show as embodiment of the invention with bilateral freely accessible end areas along the free portion end. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1 a    shows a medical implant  1  with a surface substrate  2 . The first substrate portion  3  forms a compression sleeve, that is the free portion end  4  of the first substrate portion  3  is wound about the spatial axis  5  forming at least one winding. In  FIG. 1 a   ) two one half windings are produced. A second, not wound substrate portion  6  integrally adjoins the first substrate portion  3 . 
     Firmly fastened centrally along the free portion end  4  is one end of a strand of material  8 , which preferably is a thread, strip or comparable attachment that transits tensile forces. The firm connection  10  is at least one of bonded/frictional and interlocking non-detachable connection. Starting from the place of connection  10 , the strand of material  8  extends through openings  11  which are provided in the first substrate portion  3  and are shown being in wound state, with radially overlaps each other in a congruent manner. In this way the strand of material  8  traverses the compression sleeve from inside to outside. The end of the stand of material opposite the connection  10  is locally connected to the second substrate portion  6  in the form of a detachable firm joint connection  12 . In the area of the joint connection  12 , on the surface substrate  2 , an opening  13  is provided through which the strand of material  8  passes and, preferably by means of knotting, is connected to the second substrate portion  6 . 
     Through the central application along the longitudinal cuff extension L of the strand material  8  on portion end  4 , tensile forces are symmetrically transferred to the portion end  4  with unrolling of the compression sleeve being prevented. In addition, through the symmetrical force transmission, asymmetrical stress conditions, as illustrated in  FIG. 3 b   ) and  c ), are avoided. 
     Instead of a single strand material, the embodiment illustrated in figure lb has two separate strand materials  8  which each are a surgical thread, which is unilaterally firmed fixed to the ends  41 ,  42  of the free portion end  4  of the first substrate portion  3 . At the free ends  81 ,  82 , both strands of material  8  are attached to the second substrate portion  6  via a detachably fixed joint connections  9 . In this case also, the joint connections  9 , are formed by each passing through the surface substrate  2  in the second substrate portion  6 . 
       FIG. 1 c   ) illustrates an embodiment, which instead of two threads of materials, two strip strands of materials  8  are each integrally connected on the ends  41 ,  42  of the free portion end  2  of the first substrate portion  3 . The opposite strip ends  81 ,  82  lead into corresponding slit-shaped recesses  13  within the surface substrate  2  of the second substrate portion  6  and are firmly connected thereto in a detachable manner. 
       FIGS. 4 a  and  b    respectively show a perspective oblique view of a medical implant  1 , as well as a view from above in an unwound state. The portion end  4  of the first substrate portion  3  comprises two tabs  14 , which laterally project beyond the first substrate portion  3 , in the wound state of the first substrate portion  3  which extend into slit-shaped recesses  15  on the second substrate portion  6 , to form a detachable fixed frictional and interlocking connection. The slit-shaped recesses  15  are located in respective lateral hatched areas  16  of the second substrate portion  6 , which on both sides project beyond the longitudinal cuff extension L. The tabs  14  which engage the slit-shaped recesses  5 , like the thread-like or strip-shaped strand material  8 , prevent uncontrolled loosening of the compression sleeve from a nerve fiber bundle. At the same time, the slit-shaped recesses  15  have a slit length  17  which in comparison with the tab width is dimensioned to be slightly larger so that the tabs  14  are moveable to a limited extend along the slit-shaped recesses  15  and the compression sleeve can follow at least one of the natural deformations and expansions of a nerve fiber bundle. 
       FIGS. 5 a   ),  b ) show an alternative example of embodiment for forming the fastening provisions according to the invention.  FIG. 5 a   ) shows a view from above of the surface substrate  2  of the compression sleeve in the unwound state and  FIG. 5 b   ) show a perspective view of the medical implant in the form of a compression sleeve. The first substrate portion  3  is configured in a trapezoidal manner so that the longitudinal cuff extension L within the first substrate portion  3  tapers evenly along the winding extension W with increasing distance to the area of portion end  4 . See the view from above of the unwound surface substrate  3  in accordance with  FIG. 5 a   ). By winding the first substrate portion  3  about the spatial axis  5 , the ends  41 ,  42  of the free end portion  4  of the first substrate portion  3  each project laterally outwardly in a freely accessible manner. See the perspective oblique view according to  FIG. 5 b   ). In this way the thread or strip strand materials  8  can be firmly joined to the ends  41 ,  42  in an uncomplicated manner. The opposite ends of the strand materials  8  are, like in the aforementioned examples of embodiment, detachably firmly fixed in the area of the second substrate portion  6 . Openings  13 , through which the end sections of the strand materials  8  pass and which can be knotted. 
     It is of course possible combine the measures described in the above examples of embodiment with each other. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  Medical implant 
           2  Surface substrate 
           3  First substrate portion 
           4  Free portion end 
           41 ,  42  Ends of the portion end 
           5  Spatial axis 
           6  Second substrate portion 
           61  Surface portion designed in the form of a web 
           7  Connecting structure 
           8  Strand material 
           9  Joint connection 
           10  Connection 
           11  Opening 
           12  Joint connection 
           13  Opening 
           14  Tab 
           15  Slit-shaped recess 
           16  Lateral area 
           17  Length of the slit-like recess 
         S Interface 
         H Cylindrical hollow space 
         E Constriction 
         A Widening 
         W Winding extension 
         L Longitudinal cuff extension 
         N Nerve fiber bundle 
         F External force