Abstract:
A subcutaneous, intramuscular bearing ( 1 ) for a rigid transcutaneous implant ( 2 ) is provided, for anchoring intracorporally in a bone stump and having an intermediate piece ( 3 ) between the implant ( 2 ) and an extracorporal coupling for coupling on the implant. A rigid bushing ( 5 ) is tightly connected to the intermediate piece ( 3 ), such that between the wall of the bushing ( 5 ) and the intermediate piece ( 3 ) an annular space ( 6 ) is formed, which is closed in the intracorporal direction, for receiving and setting the extracorporal coupling. The outer wall of the bushing ( 5 ) has an open-meshed, three-dimensional lattice structure ( 8 ) and a lattice-free distal region having a width B. A spring ring ( 9 ) is set in the annular space ( 6 ) from the distal end, moved with a telescoping motion, and locked under exertion of its spring effect.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a subcutaneous, intramuscular bearing for a rigid transcutaneous implant, which can be anchored intracorporally in a bone stump and which has an intermediate piece between the implant and an extracorporal coupling that can be coupled to this intermediate piece. 
   Such a bearing is known from German published patent application DE 100 40 590 A1. The bearing described in this publication comprises a flexible material and it has a bushing, which closely surrounds the implant distally. The bearing also has an intracorporally arranged coupling sleeve in the form of flexible pleated bellows, which is proximally connected to the bushing in a sealed manner with a molded collar, such that a hollow space of a minimum width remains free between the inner wall of the pleated bellows and the outer wall of the bushing. In this way, a flexible lattice network is arranged distally on the pleated bellows and is connected on the distal end to another lattice network with a higher modulus of elasticity. 
   With this bearing, the goal is achieved that soft parts can move relative to the rigid implant without exposing the point in the body-part stump where the implant emerges to an increased risk of inflammation. 
   Even if this known bearing is successfully inserted in practice, there is the risk that in the case, for example, when the point where the implant emerges through the thigh stump is cleaned with a hollow needle, the flexible material, in most cases silicone, is also pierced and a contamination occurs. 
   BRIEF SUMMARY OF THE INVENTION 
   Against this background, it is now an object of the present invention to improve a conventional subcutaneous, intramuscular bearing of the type mentioned at the outset, such that safety against contamination of the point in the body where the implant emerges (emergence point) and the adjacent regions of the thigh stump is significantly increased, and inadvertent removal of the germ barrier is prevented. 
   Accordingly, it is proposed according to a first embodiment that the bearing have a rigid bushing firmly connected to the intermediate piece, and that, between the wall of the bushing and the intermediate piece, an annular space be provided, which is closed in the intracorporal direction and in which the extracorporal coupling can be set. On the outer wall of the bushing there is an open-meshed, three-dimensional lattice structure, except for a region maintained in the distal region having a width B, preferably of up to about 2 cm. Furthermore, a spring ring is provided, which can be set into the annular space from the distal end, which can move with a telescoping motion, and which can be locked under exertion of its spring force. 
   Relative to the known bearing, the present bushing is a rigid element, which cannot be pierced, e.g., by hollow injection needles. The open-meshed, three-dimensional lattice structure provided on the outer wall of the bushing serves to allow connective tissue to form a structure therein and thus form a germ barrier. The distal region remains free from the three-dimensional lattice structure to allow movement of the surrounding connective tissue for compensating movements. 
   The spring ring is pressed together, for example with a spring chuck, and inserted into the annular space and pushed in, so that the layer of connective tissue starting at the end of the three-dimensional lattice structure on the bushing bridges over up to the skin of the thigh stump. The adjustability is tailored according to patient-specific conditions. 
   The surgery now proceeds so that, after the amputation of the thigh, the transcutaneous implant is first anchored in the bone stump, and the distal end is provided with the intermediate piece. Then, the thigh stump is closed until the transcutaneous implant has grown into the bone stump. Finally, after approximately 6 to 8 weeks, the thigh stump is opened with a skin cutting device and the spring ring is pressed together by means of a spring chuck, so that the spring ring can be guided into the annular space. 
   The spring ring is preferably a bent out ring with a radial slot. The outward flange then lies from the outside against the skin of the thigh stump. The radial slot is used for two purposes: first, the spring ring can be pressed together for insertion into the annular space. After removing the spring chuck, the ring expands in circumference and thereby generates the spring force necessary for the locking. In addition, the radial slot serves for drainage or discharge of internal bodily secretions. 
   The mesh spacings of the three-dimensional lattice structure on the bushing are preferably about 50 to 2500 μm. These mesh spacings are relatively large, but hold a sufficient amount of connective tissue surrounding the mesh, so that a reliable germ barrier can be produced. 
   The bushing can be connected firmly to the intermediate piece by heat-shrinking the bushing on the intermediate piece. Alternatively, it can also be fused with the intermediate piece. It is also possible for the bushing to be formed integrally as one piece with the intermediate piece. In each case, it must be guaranteed that the connection between the bushing and the bearing is tight and rigid and can withstand the applied loads. 
   A second embodiment provides a subcutaneous bearing: having a rigid bushing connected firmly to the intermediate piece with a coupling element, which is closed in the intracorporal direction and to which the extracorporal coupling can be coupled; having an open-meshed, three-dimensional lattice structure on the outer wall of the bushing while maintaining a free width B in the distal region; having an activatable device provided in the region where the implant emerges from the leg stump for application of bioactive material; and having a spring ring, which can be set into the coupling element from the distal end, which can move with a telescoping motion, and which can be locked by exerting its spring effect. 
   The bearing according to this second embodiment differs from that according to the first embodiment essentially by the activatable device provided in the region where the implant emerges from the leg stump for application of bioactive material. In this way, an optimal maintenance or care of the point where the implant emerges from the thigh stump is guaranteed. Here, the term “bioactive material” is understood to mean a medicine. 
   The critical region where the implant emerges from the thigh stump can thus be medicinally cared for with a view to an improved wound healing effect, but also with a view to a preventive effect against inflammation. The wound healing is greatly improved by the application of medicine. 
   According to a first preferred form of this second embodiment, the activatable device for application of bioactive material has at least one annular groove formed in the outer wall of the bushing and at least one hollow ring that can be set in the annular groove, the hollow ring being made of elastic and porous material with a molded inlet port, through which the hollow ring can be supplied with liquid bioactive material. Through the inlet port, the bioactive material is fed into the interior of the hollow ring. The material exits this ring over time due to the porosity, wets the regions of the open-meshed implant lying underneath, and then flows down in the direction towards the point where the implant emerges from the thigh stump. The hollow ring represents a certain reservoir. The storage capacity in terms of time is decisively influenced by the porosity of the material, from which it is made. Preferably, this is selected so that bioactive material need only be supplied approximately every week. 
   In an especially preferred refinement, the hollow ring and the inlet port comprise a silicone. Here, the hollow ring and the inlet port are preferably formed integrally. 
   According to a second preferred form of the second embodiment, the device for applying the bioactive material includes at least one annular groove formed in the outer wall of the bushing and at least one branch channel arranged laterally next to the coupling element in the bushing, which extends so that it intersects the periphery of the one or more annular grooves. The branch channel(s) serve for applying the bioactive material. After the application of the bioactive material, the branch channel(s) can be re-closed, preferably by a seal, for example by a screw. Therefore, this embodiment is concerned less with the long-term application of the bioactive material than with the instantaneous and short-term supply of material to the point where the implant emerges from the thigh stump. 
   In one especially preferred refinement of this embodiment, at least one branch channel, particularly preferred three branch channels, extend on the outer wall of the bushing in the lower region of the three-dimensional lattice structure, between the lowermost annular groove and the three-dimensional lattice free region of the bushing, for transporting the bioactive material to the point where the implant emerges from the leg stump. 
   According to a third concrete preferred form of the second embodiment, an annular space is arranged around the coupling element, in which space a supply of elastic film made from bioactive material is stored. Here, the film emerges from the annular space through an annular slot in the bushing and runs along the three-dimensional lattice structure-free region of the bushing to the point where the implant emerges from the leg stump. Here, it surrounds the bushing like a tube. In the three-dimensional lattice structure-free region, the film adheres to the tissue or skin surrounding it. Due to the growth of the skin and tissue, the film is pulled outwardly, wherein it carries possible germs and bacteria with it. The growth of the tissue and skin equals a maximum of about 1 mm per day. Correspondingly, the film is pulled from the intermediate piece by this measure. Storage times of up to one year for the film supply are possible before the annular space must be charged with a new film supply. 
   This embodiment is not targeted to an instantaneous short-term wound healing treatment. Instead, here the long-term preventive effect against possible infection is in the foreground. 
   All of the forms of the bearing according to the second embodiment can be improved even more advantageously by embodying the coupling element as a conical clamping sleeve. This permits a smaller overall size than a double cone, as was described in the scope of the first embodiment. In general, all refinements of the first embodiment can be applied to the second embodiment. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
       FIG. 1  is a longitudinal sectional view of a subcutaneous, intramuscular bearing, coupled to a transcutaneous implant according to a first embodiment of the invention; 
       FIG. 2  is a perspective view of an embodiment of the spring ring; 
       FIG. 3  is an exploded schematic sectional view of an intermediate piece of the bearing with bushing and spring ring; 
       FIG. 4  is a schematic side view of a transcutaneous implant with the intermediate piece according to a second embodiment of the invention; 
       FIG. 5  is an enlarged side view of the intermediate piece of  FIG. 4 ; 
       FIGS. 6(   a ) and  6 ( b ) are respectively top view (a) and side view (b) of the hollow ring shown in  FIG. 4 ; 
       FIGS. 7(   a ) and  7 ( b ) are respectively a schematic cross-sectional view (a) and a schematic view (b) of the intermediate piece according to the second embodiment; and 
       FIG. 8  is a cross-sectional view of the intermediate piece according to a third embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  gives a first overview. A rigid transcutaneous implant  2  is inserted into a femur stump (not shown). The open meshed, three-dimensional lattice structure  28  is used in the present case for integrating bone material for secondary fixation of the implant  2  into the bone. It is sealed on the distal end by a metal sleeve  12 , which seals the femur stump. For this purpose, the metal sleeve  12  also carries a three-dimensional, open-meshed lattice structure  28 , in which bone material should grow. 
   In the interior of the metal sleeve  12 , a conical clamping sleeve  13  is formed. This is provided for manufacturing a conical clamp connecting with the intermediate piece  3  presently embodied as a double cone. The intermediate piece  3  has a cylindrical center section  11 , on which the bushing  5  is heat-shrunk. Another cone  14  connects to the center section  11  on the distal side for producing a conical clamp with a conical clamping sleeve in an adapter of the extracorporal coupling (not shown). 
   The bushing  5  is formed so that, between its wall and the intermediate piece  3 , there is an annular space  6  closed in the intracorporal or proximal direction. In this annular space  6 , the extracorporal coupling is set. 
   The outer side of the bushing  5  has in the proximal region an open-meshed, three-dimensional lattice structure  8 , into which the connective tissue surrounding the bushing  5  after implantation grows by granulation in order to form a germ barrier. In the distal region of the outer wall of the bushing  5 , there is no three-dimensional lattice structure in a region with a width B ( FIG. 3 ). This permits a compensating motion of the surrounding connective tissue without leading to stress in the tissue. 
   For the implantation, the transcutaneous implant  2  is first implanted in the femur stump with the metal sleeve  12  mounted thereon, and the thigh stump is then closed for setting the implant. After 6 to 8 weeks sufficient bone material has grown into the three-dimensional lattice structure  28  of the implant  2 , so that this remains stable even under loads in the femur stump. Simultaneously, connective tissue grows into the three-dimensional lattice structure  18  on the outer wall of the metal sleeve  12  to form a first germ barrier. 
   After the mentioned time span, the thigh stump is reopened and the intermediate piece  3  with the bushing  5  is guided into the opening in the femur stump and locked there by a conical clamp connection between the double cone and the clamping sleeve  13 . An additional securing device  17  (here in the form of a screw) serves for additional securing. 
   After opening the thigh stump, the spring ring  9  is pressed together by a spring chuck ( FIG. 2 ), wherein the radial slot  10  is provided and inserted into the annular space  6 . By telescopic insertion or shifting of the ring  9  in the annular space, the patient-specific distance between the distal end of the bushing  5  and the skin of the thigh stump can be set. The bent flange  19  of the spring ring  9  then contacts the skin of the thigh stump. The slot  10  serves, on the one hand, for the possibility of pressing the spring ring together with a spring chuck in order to generate a spring force when the spring chuck is released and, on the other hand, for discharge of possible bodily secretions. 
   A measurement bolt  20  is now inserted into the annular space  6 . With the help of this bolt, the required length for the extracorporal coupling can be determined. 
   The relationships are clearly seen again, enlarged in  FIG. 3 . Here, the intermediate piece  3  with heat-shrunk bushing  5  is shown isolated (exploded view), so that an annular space  6  results between the cone  14  and the bushing  5 . 
   The heat-shrinking of the bushing  5  on the intermediate piece  3  is now especially successful due to the cylindrical center section  11  of the intermediate piece  3 . Clearly recognizable is also the open-meshed, three-dimensional lattice structure  8  on the outer wall of the bushing  5 , into which the connective tissue, surrounding it after implantation, grows for forming the germ barrier. Shown in  FIG. 3  is also the width B, i.e., the width of the region, which is free of a three-dimensional lattice structure  8  on the distal end. From  FIG. 3  it can also be seen, based on the indicating arrow, how the clamping ring  9  is inserted into the annular space  6 . After finding the correct insertion depth, the spring chuck is then released and the spring ring  9  expands, so that it lies against the inner wall of the bushing  5  and hardens in this position. 
     FIG. 4  again shows the rigid transcutaneous implant  102 , which can be anchored intracorporally in a bone stump. It again has an intermediate piece  103  between the implant  102  and an extracorporal coupling  107  that can be coupled to the implant. 
   A rigid bushing  105  is connected to the intermediate piece  103 . The bushing  105  has a coupling element  106  ( FIGS. 7   a  and  8 ) closed in the intracorporal direction, to which the extracorporal coupling  107  is coupled. 
   The outer wall of the bushing  105  again carries an open-meshed, three-dimensional lattice structure  108 , in which connective tissue is integrated to form a germ barrier. The metal sleeve  119  closing the implant  102  similarly carries the three-dimensional, open-meshed lattice structure  118  for this same purpose. 
   An annular ring groove  110  is embedded in the outer wall of the bushing  105 , in the embodiment shown. In this annular groove  110 , a hollow ring  111  with a connected inlet port  112  is attached. Details of the hollow ring  111  can be seen from  FIG. 6 . 
   The inlet port  112  is formed directly on the hollow ring  111 . Both preferably comprise silicone. The hollow ring  111  is porous or has small holes  120 , from which the supplied bioactive material can emerge and thus can perform its therapeutic effect in the region of the point where the implant emerges from the thigh stump. 
     FIGS. 7(   a ) and ( b ) show a second embodiment of the intermediate piece  103 . The bushing  105 , again coated with the three-dimensional lattice structure  108 , now has an annular ring groove  110 . As one can see in the sectional view ( FIG. 7   a ), in the right side of the bushing  105  there is a branch channel  113 , which is presently closed with a tightened screw  121 . The branch channel  113  is formed in the bushing  105 , so that it intersects the periphery of the annular groove  110 , so that a bioactive material brought into the branch channel  113  can emerge from the branch channel  113  into the annular groove  110  to perform there its therapeutic effect. For applying the bioactive material, the screw  121  must be unscrewed from the branch channel  113 , after which the bioactive material can then be injected into the channel  113 , for example with a hollow needle. After successful treatment, the branch channel  113  is re-closed with the screw  121 . 
   So that a good distribution of the bioactive material can take place, three branch channels  114  are now provided ( FIG. 7   b ), which connect the annular groove  110  to the three-dimensional lattice structure region of the bushing  105  with the width B. The bioactive material then flows from the annular groove  110  through the branch channels  114  in the direction of the implant emergenece. point. 
   Finally,  FIG. 8  shows the third preferred embodiment of the intermediate piece  103 . Here, an annular ring space  115  is formed around the coupling element  106 . In the annular space  115 , there is a supply of an elastic film  116  made of bioactive material. 
   The film in the form of a pressed-together tube emerges through a ring-shaped slot  117  from the annular space  115  and then runs along the three-dimensional lattice-free region of the bushing  105  up to the emergence point of the implant from the leg stump. The film  116  here surrounds this section of the sleeve  105  in the shape of a tube. In the bottom region, the film  116  adheres to the surrounding tissue or skin and is pulled outwards with the growth of the skin and the tissue through the region where the implant emerges. In this way, the film carries possible germs outwardly with it. The patient can then cut off the discharged film material  116  from time to time. 
   It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.