Abstract:
A device for implanting marking bodies into a bone is provided in the form of forceps whereby comprising a medial forceps handle, a lateral forceps handle, a medial forceps limb, a lateral forceps limb, and a spring element. The spring element acts upon the medial forceps handle and upon the lateral forceps handle, and the medial forceps limb and the lateral forceps limb can be displaced parallel relative to one another by means of a four-bar linkage for ejecting the marking bodies. A magazine containing the marking bodies can be slid onto a magazine holding fixture situated on the lateral forceps limb.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This is a divisional of U.S. application Ser. No. 10/505,463 which is the U.S. national phase of International Application PCT/EP03/02567 filed Mar. 12, 2003, the disclosure of which is incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Disclosure  
         [0003]     The disclosure relates to a device for the implantation of marking bodies in a human or animal bone and a magazine with marking bodies for this device.  
         [0004]     2. Related Technology  
         [0005]     Marking bodies, preferably metallic balls, can be introduced into the human or animal skeleton to allow a quantification of the migration of implants, in particular joint prostheses, especially replacement knee joints and hip joints. For this purpose, a number of devices are already known, which operate in a similar manner to an injection syringe, one marking ball being placed by hand into a cannula of the injection syringe for each use and then introduced into the bone.  
         [0006]     The particular disadvantage with the known devices is that, during the operation, the marking balls have to be individually loaded or unloaded manually by the operator using tweezers or a similar instrument, which prolongs the operating time.  
         [0007]     It is also disadvantageous that, although the marking balls can be packed in a sterile manner before loading, they become unsterile after loading.  
         [0008]     Another device for the implantation of marking bodies in a bone, which comprises a magazine for the marking bodies and an ejector mechanism for the marking bodies, is known from DE 297 17 890 U1. This device is designed in the form of a pistol. The magazine is designed as a revolving chamber and contains several marking bodies.  
         [0009]     The disadvantage of this device is that the marking balls must be ejected and implanted one after the other, so that the spacing between marking balls is more or less random, and it is therefore not possible to ensure a reproducible spacing between the individual marking balls.  
       SUMMARY  
       [0010]     The disclosure provides a device, which allows a simple and rapid, simultaneous insertion of at least one, preferably several, preferably sterile marking bodies at a defined position relative to one another into the skeleton in order to quantify the migration of implant components relative to the bone, and a magazine with marking bodies for this device.  
         [0011]     The device is designed in the form of forceps, and including medial and lateral forceps handles and medial and lateral forceps limbs wherein a magazine with at least one marking body can be attached to a magazine retained on one of the forceps limbs.  
         [0012]     The disclosure also provides a magazine useful in the device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The device is explained in greater detail below with reference to a preferred exemplary embodiment on the basis of the drawings. The drawings are as follows:  
         [0014]      FIG. 1  shows a lateral view of an exemplary embodiment of the device according to the disclosure;  
         [0015]      FIG. 2  shows a lateral view of the exemplary embodiment of the device according to the disclosure with the magazine fitted;  
         [0016]      FIG. 3  shows a lateral view of the exemplary embodiment of the device according to the disclosure with the magazine fitted and a distal guide attached;  
         [0017]      FIG. 4  shows a lateral view of the exemplary embodiment of the device according to the disclosure with the magazine fitted and the attached distal guide inserted into the bone cavity;  
         [0018]      FIG. 5  shows a plan view of an exemplary embodiment of the magazine to be used with the device according to the disclosure, with pre-loaded marking balls;  
         [0019]      FIG. 6  shows a cross-section through the magazine shown in  FIG. 5  along the line marked VI-VI. 
     
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 1  shows a lateral view of an exemplary embodiment of a device  1 , which comprises a medial forceps handle  2 , a lateral forceps handle  3 , a medial forceps limb  4  and a lateral forceps limb  5 . The forceps handles  2  and  3  and the forceps limbs  4  and  5  are connected to one another via a four-lever articulated joint  6 . When the forceps handles  2  and  3  are activated, the two forceps limbs  4 ,  5  are displaced parallel to one another.  
         [0021]     A spring element  7  which, in the exemplary embodiment consists of two complementary plate springs  8 ,  9  attached to each forceps handle  2 ,  3 , is deformed in a resilient manner when the forceps handles  2 ,  3  are activated. When the forceps handles  2  and  3  are released, the spring element  7  acts to push the forceps handles  2 ,  3  apart again and the two forceps limbs  4 ,  5  accordingly move away from one another.  
         [0022]     A magazine  10 , which contains marking bodies  11  in a given arrangement, is attached to a magazine retainer  12 , in the exemplary embodiment, in the form of a magazine guide attached to the lateral side of the lateral forceps arm  5 , and, in the exemplary embodiment, pushed up to a stop  13 , so that boreholes  14  of the magazine  10  are in mutual alignment with pins  15 . The pins  15  are attached to the medial forceps limb  4  and point towards the lateral forceps limb  5 , on which the magazine  10  is attached by plug-on or push-on attachment. The pins  15  provide a concave tip to ensure that they do not slip sideways on the marking bodies  11 , inserting them from the magazine  10  into a bone  20  in a defined position relative to one another, as described below.  
         [0023]     In the same view as  FIG. 1 ,  FIG. 2  shows the device  1  with the magazine fitted and with a guide  17 , which can be plugged onto a distal end of the lateral forceps limb  5 . In this context, the guide  17  comprises a lateral guide  18  and a medial guide  19 , which can be displaced relative to one another.  
         [0024]      FIG. 3  shows the lateral guide  18  already fitted to the lateral forceps limb  5 . The medial guide  19 , which is fixed to the lateral guide  18  with an attachment device, which is not presented in greater detail here, can be displaced relative to the lateral guide  18 . Accordingly, the longitudinal position of the magazine  10  and therefore also the position of the marking bodies  11  relative to the bone  20  can be selected.  
         [0025]      FIG. 4  shows how the device  1  is inserted into a cavity  21  of the bone  20 . In the exemplary embodiment, the bone is a femur  21 , into the proximal end of which a cemented or uncemented replacement hip joint is to be inserted after referencing the bone by means of the device  1  according to the invention. In this diagram, by comparison with  FIG. 3 , the position of the medial guide  19  is displaced in the distal direction, so that the depth of insertion of the device  1  is limited. With the lateral guide  18  and the medial guide  19  in the position shown in  FIG. 3 , the device  1  could be pushed deeper into the cavity  21 ; with a further distal displacement of the medial guide  19  relative to the lateral guide  18 , the depth of insertion would be reduced.  
         [0026]     The diameter of the marking bodies  11 , preferably designed as marking balls, is typically 0.5 mm to 2.0 mm. With cylindrical marking elements  11 , these may be 3 mm to 6 mm long, and then preferably have a conical tip with a conical angle between 30° and 90°. Bio-compatible materials such as tantalum, pure titanium, titanium alloys, stainless steel, calcium phosphate ceramics, technical ceramics, resorbable ceramics, polymers or composites, which, through x-ray absorption, produce a clear contrast on the x-ray image relative to the surrounding bone  20 , are suitable materials for the marking bodies  11 .  
         [0027]     After positioning the device as required in the cavity  21  with the assistance of the guide  17 , the device  1  for the insertion of the marking bodies  11  is activated by pressing together the medial forceps handle  2  and the lateral forceps handle  3  against the force of the spring element  7 . As a result of the four-lever articulated joint  6 , the medial forceps limb  4  is moved in a parallel manner towards the lateral forceps limb  5  until the pins  15  are in contact with the marking bodies  11  arranged in the magazine. As a result of the continued squeezing together of the device  1 , the pins  15  press the marking bodies  11  through the boreholes  14  into the tissue structure of the bone  20 .  
         [0028]     At least two marking bodies are advantageously arranged in at least two rows in a non-collinear manner, thereby allowing the possibility of two-dimensional marking.  
         [0029]     In this context, the marking bodies are preferably spherical or cylindrical with a conical tip and are formed of material, which, through x-ray absorption, shows an adequately high contrast by comparison with the surrounding bone tissue.  
         [0030]     Furthermore, it is advantageous that pins engage in the magazine in such a manner that the marking bodies are pressed simply and simultaneously into the bone tissue up to a predetermined depth.  
         [0031]     A guide advantageously allows a limitation and regulation of the depth of insertin of the device into a bone cavity.  
         [0032]      FIG. 5  shows a plan view of a magazine  10  to be used with the device  1  according to the invention. In the left-hand diagram, the magazine  10  is empty; while in the right-hand diagram, the magazine is loaded with three marking bodies  11 . After insertion into the bone, preferably with pins  15  of identical length, the marking bodies  11  from the magazine  10  are arranged in such a manner that they form a bone-reference system, preferably a plane, when three marking bodies  11  are used. As a result, they provide reliable information about the setting movement (migration) of implant components with reference to the surrounding bone. In this context, the pre-loaded magazine  10  is preferably packed in a sterile manner and can be fitted to the device  1  in a sterile manner.  
         [0033]      FIG. 6  shows a cross-section of the magazine  10  presented in  FIG. 5  along the line VI-VI in  FIG. 5 . The marking bodies  11 , which are spherical in this exemplary embodiment, are arranged in the boreholes  14 . To accommodate the angle of the bone  20 , the magazine is designed in this context to be slightly trapezoidal with the narrow side in the distal direction. However, depending on requirements, general four-sided or rectangular profiles may also be used.