Patent Abstract:
The invention relates to a fixation device with clamping jaws and with rods connecting the clamping jaws, said rods being adjustable axially and angularly for positioning relative to the clamping jaws and clampable in the desired position, and with fixation and retaining pins that are receivable in a clampable fashion in the clamping jaws. According to the invention, a fixation pin applicator can be connected in a releasable fashion to the clamping jaws. A fixation pin can be brought into a desired position by means of the fixation pin applicator.

Full Description:
RELATED APPLICATIONS  
       [0001]    This is continuation of U.S. Ser. No. 09/400,436, filed on Sep. 21, 1999, which is a continuation-in-part of U.S. Ser. No. 09/011,924, filed on Jun. 8, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention consists of a fixation device used to immobilize portions of a fractured bone relative to one another, and more specifically to a device to immobilize such portions of fractured bone by attaching an adjustable rigid frame to the fractured bone.  
         DESCRIPTION OF RELATED ART  
         [0003]    A fixation device is known from DE 41 13 083 A1. This fixation device has three or four rings used as clamping jaws, said rings being designed as either closed or sector rings. The rings are connected with one another by rods. For mutual positioning of the rings, the rods are axially displaceable and pivotable with respect to the rings and can be clamped in position respective to the rings. Holders are provided on the rings for bone wires or bone fixation and retaining pins.  
           [0004]    The known fixation device permits free relative movement of the rings in space, so that the bone fragments can be positioned and repositioned very exactly. The fixation device is secured in a stable fashion in precisely set positions by clamping the rods to the rings.  
           [0005]    A fixation device is also known from DE 94 01 291 U, that has only two clamping jaws for provisional emergency care of the patient, with each sector ring having two holders for the clamping pins and with each holder having at least two receptacles for the clamping pins, i.e. the fixation and retaining pins. The receptacles are offset with respect to one another perpendicularly with respect to the plane of the sector ring. The clamping pins are designed as cylindrical pins that have a small point at their anterior ends, said point being capable of being pressed superficially into the bone. These clamping pins are provided with an external thread in their rear areas. After the clamping jaws are positioned, the clamping pins are then advanced by the suitably designed receptacle that cooperates with the external threads of the clamping pins until they rest on the surface of the bone and provide the necessary grip. This fixation of the clamping pins is cumbersome and time-consuming.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is directed to a fixation device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
           [0007]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the apparatus and method particularly pointed out in the written description and claims hereof, as well as the appended drawings.  
           [0008]    To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the invention is a fixation device with clamping jaws having rods connecting the clamping jaws, said rods being adjustable axially and angularly relative to the clamping jaws and being clampable in a desired position, and with fixation and retaining pins that can be received in a clampable fashion in the clamping jaws. The device has a fixation pin applicator releasably connectable with the clamping jaws, by means of which applicator a fixation pin can be brought into a desired position.  
           [0009]    Accordingly, the clamping jaws are releasably connectable with a fixation pin applicator, by means of which applicator a fixation pin can be brought into the corresponding desired position on the surface of the bone.  
           [0010]    The fixation device offers a minimally invasive alternative to surgery of fractures of bones such as, for example, the tibia. The individual fragments are secured in the area of the cortex in each instance without the medullary cavity being opened (so-called pinless nail method). The fixation device can be applied rapidly and simply because of the fixation pin applicator provided according to the invention, and permits intra operative and postoperative repositioning of the device and of the bone fragments in all planes.  
           [0011]    This technique avoids contamination of the medullary cavity. A direct procedural change to using the marrow nailing method poses no risk, i.e., it can be performed without an increased risk of infection. In addition, when the fixation device according to the invention is used, the device can remain in place even during marrow nailing, if that procedure is required, considerably simplifying marrow nailing and also allowing the procedure to be performed more rapidly.  
           [0012]    In a different embodiment, the invention is a fixation device that includes a fixation pin applicator that can be designed in the form of a pistol, and can have in addition to a fixed handle, a movable handle part by which a plunger acting on the fixation pin can be displaced.  
           [0013]    In the fixation pin applicator, a transport plate for moving the plunger against the force of a spring can be moved by the movable handle part. The plunger and therefore the fixation pin is thus moved toward the desired position by this transport plate.  
           [0014]    The fixation pin applicator can be secured to the clamping jaw by a latching mechanism with a catching pin in an especially simple fashion. To release the latching mechanism, the fixation pin applicator has an externally operable release that is connected to the spring loaded latching mechanism. The clamping jaw can also be held in place by a spring loaded ball affixed to the fixation pin applicator, and cooperating with a corresponding depression in the clamping jaw.  
           [0015]    The fixation device can consist of two clamping jaws that can be maintained in the desired position with respect to one another by corresponding rods. According to one advantageous embodiment of the invention, however, additional connecting elements can be linked to the clamping jaws, said elements having suitable clamping devices to receive additional rods and hence to connect additional clamping jaws. The fixation device can thus be expanded as desired.  
           [0016]    The fixation and retaining pins can have different shapes. In particular, the retaining pins can be made straight or bent. They can also be designed as so-called dual pins, which are forked pins located parallel to one another. The retaining pins can also be made spoon-shaped at their ends and provided with a plurality of points parallel to one another. These pins also can be in the form of single or dual pins.  
           [0017]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    The accompanying drawings are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the objects, advantages, and principles of the invention.  
         [0019]    In the drawings,  
         [0020]    [0020]FIG. 1 is a side elevation view of the fixation device with the fixation pin applicator in place;  
         [0021]    [0021]FIG. 2 is a view as in FIG. 1, with the fixation pin applicator shown in another operating position;  
         [0022]    [0022]FIG. 3 is a perspective view showing two clamping jaws connected by two axial rods, according to an embodiment of the invention;  
         [0023]    [0023]FIG. 4 is a top plan view showing the two clamping jaws and axial rods shown in FIG. 3;  
         [0024]    [0024]FIG. 5 is an exploded view showing a clamping jaw according to the invention;  
         [0025]    [0025]FIG. 6 is a perspective view showing one embodiment of the retaining pin according to the invention;  
         [0026]    [0026]FIG. 7 is a perspective view illustrating the fixation device applied to a fractured bone;  
         [0027]    [0027]FIG. 8 is a perspective view showing a second embodiment of the retaining pin;  
         [0028]    [0028]FIG. 9 is a diagram illustrating the connection process between the clamping jaw and the fixation pin applicator;  
         [0029]    [0029]FIG. 10 is a diagram showing an exploded view of an embodiment of the fixation pin applicator; and  
         [0030]    [0030]FIG. 11 is a cross sectional view of the fixation pin applicator shown in FIG. 10, also showing three views of the guide way. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0031]    The fixation device is formed from a plurality of clamping jaws. FIGS. 1 and 2 show one such clamping jaw  10 , connected to a fixation pin applicator  22 . As shown in FIGS. 3 and 4, clamping jaws  10  can be formed from straight sections bent at an angle with respect to one another, but can also be formed of sector rings or of curved segments. Clamping jaws  10  are connected by axial rods  40  that are axially displaceable in the clamping jaws and can be pivoted relative to the plane of clamping jaws  10 . As a result, simple three-dimensional adjustment of clamping jaws  10  relative to one another is possible.  
         [0032]    [0032]FIGS. 3 and 4 show one embodiment of an arrangement of two clamping jaws  10  and two axial rods  40 . Axial rods  40  can pivot and can translate axially within clamping receptacles  12 . Once clamping jaws  10  are positioned in a desired relative position, the axial rods  40  can be fixed to the clamping jaws  10  in a manner to be described later, so as to maintain the desired relative position between the two clamping jaws  10 . In a preferred embodiment, the axial rods  40  are made of carbon fiber, however, other rigid materials could also be used.  
         [0033]    When the desired position of the clamping jaws  10  is reached, the axial rods  40  are immobilized to maintain both axial and rotational position with respect to clamping jaws  10 . Clamping jaws  10  are connected in stable fashion with one another, in a fixed relative position in space.  
         [0034]    In a different embodiment according to the invention, more than two clamping jaws  10  can be connected by axial rods  40 . This embodiment may require different sets of clamping receptacles  12  to connect respective pairs of clamping jaws with axial rods  40 . For example, an add-on jaw  100  can be attached to the clamping jaw  10 , as shown in FIG. 3. Add-on jaw  100  is similar to clamping jaw  10 , but does not have provisions for pins  20  and  14 . Two sets of axial rods  40  can be attached to the combination of clamping jaw  10 , and add-on jaw  100 , using the additional clamping receptacles  12  of the add-on jaw  100 , so that more than two clamping jaws  10  can be connected together. As shown in FIGS. 3 and 4, add-on jaw  100  can be, for example, placed on top of clamping jaw  10  using guide pins  104  that fit in guide holes  106 . Add-on jaw  100  can then be secured in place using fastener  102  fitting in fastener hole  108 .  
         [0035]    As shown in FIG. 7, the clamping jaws  10  must be positioned and then maintained in a precise configuration so that a fractured bone  18  can be immobilized in a position suitable for healing. The invention can be used advantageously to treat, for example, a fractured tibia. However, other bones can also be treated by the invention. It is thus necessary that the clamping jaws  10  and axial rods  40  be easily fixed in a desired relative position, with at least one clamping jaw  10  on each side of fracture  62 .  
         [0036]    Clamping jaws  10  have two clamping receptacles  12  to receive the axial rods, shown in detail in FIG. 5. Clamping receptacles  12  are equipped with clamping balls  50  that allow swiveling and axial translation of the rods, as described in greater detail in DE 41 13083A, incorporated herein by reference in its entirety. DE 94 02 291 U describes a more general system for swiveling and axially moving rods that are connected to sector rings, and is also incorporated herein by reference in its entirety. Clamping balls  50  have a passage  54  that extends diametrically across the ball, and is designed to receive axial rods  40 . Clamping balls  50  also have slots  52  cut on their surface, along meridian lines. Slots  52  allow clamping ball  50  to contract radially by a small amount when squeezed, so that the diameter of passage  54  is reduced. The specific configuration of the slots  52  is not important, as long as they allow a reduction in diameter of passage  54  when the clamping ball  50  is squeezed.  
         [0037]    Clamping jaw  10  is provided with a plate  56  used to squeeze clamping balls  50 . Each one of clamping balls  50  is placed in a countersunk hole  69  of clamping jaw  10 , and is held in place by plate  56 , plate  56  is attached to clamping jaw  10  with fasteners  58 , that can be, for example, screws. When screws  58  are loose, balls  50  are free to rotate in countersunk hole  69 , and the diameter of passage  54  is at its greatest value. When screws  58  are tightened, plate  56  squeezes clamping balls  50  against countersunk hole  69 , thus immobilizing them and minimizing the diameter of passage  54 , which in turn immobilizes axial rods  40 . The diameters of holes  69  and  68  are such that clamping balls  50  cannot pass through those holes.  
         [0038]    In operation, axial rods  40  are inserted in passages  54  of the clamping balls  50  of a pair of clamping jaws  10 , while screws  58  are loose. Once clamping jaws  10  are in the proper relative position, screws  58  are tightened, preventing further rotation of clamping balls  50 , and translation of axial rods  40  within passages  54 . The configuration of clamping jaws  10  and axial rods  40  cannot then be changed further.  
         [0039]    A preferred embodiment according to the invention uses two axial rods  40  per pair of clamping jaws  10 , with corresponding clamping receptacles  12 . However, a different number of axial rods can be used, depending on the desired rigidity of the assembly. Plate  56  can also be made of multiple segments, or of a single segment, as shown in the drawings. Other suitable methods of squeezing clamping balls  50  could also be used, such as an arrangement of springs.  
         [0040]    A retaining pin  14  can be inserted at one end of clamping jaw  10 , perpendicularly to clamping jaw  10 . This retaining pin  14 , as shown in the embodiment illustrated here, can be designed as a so-called double-spoon pin. For this purpose, retaining pin  14  is curved at its free end so that it is spoon-shaped, and can have a plurality of ridges or points  16  that serve for increased grip with the cortex of a bone  18 , as shown in FIG. 7.  
         [0041]    [0041]FIG. 6 shows one embodiment of a retaining pin  14  according to the invention. In this embodiment, retaining pin  14  has two prongs  42  and  44  that terminate in spoon shaped surfaces, with points  16  disposed on the concave side of the spoon shaped surfaces. As shown in FIG. 7, points  16  are designed to grip the surface of a bone  18 , to facilitate retaining the clamping jaw  10  in position with respect to the bone  18 .  
         [0042]    [0042]FIG. 8 shows a second embodiment of retaining pin  14 ′, where only one prong is used. The single prong includes a spoon shaped surface with a concave side having points  16 . Retaining pin  14  or  14 ′ is securely attached to clamping jaw  10 . This can be accomplished, for example, by using a set screw  46  shown in FIG. 5, or by any other suitable method, such as threading, spring loaded catches, or cotter pins.  
         [0043]    At the opposite free end of clamping jaw  10 , a fixation pin  20  is guided in an axially displaceable manner in the direction indicated by the double arrow “a”, as shown in FIGS. 1, 2. For axial displaceability of fixation pin  20 , in other words for positioning said pin in the cortex of bone  18 , a fixation pin applicator  22  is connected securely but releasably to clamping jaw  10  by a latching mechanism  24 , that will be described later.  
         [0044]    Fixation pin  20  slides freely in hole  70  of clamping jaw  10 , so that it can be positioned as desired abutting a portion of bone  18 , as shown in FIG. 7. Once bone  18  is securely held between retaining pin  14  and fixation pin  20 , the latter pin is secured in place on clamping jaw  10 , to firmly retain clamping jaw  10  in position on bone  18 . This is accomplished, for example, using a set nut  48  and bolt  49  shown in FIG. 5. For example, pin  20  can go through a hole in bolt  49 , so it is held in place when nut  48  is tightened on bolt  49 .  
         [0045]    Fixation pin  20  can be positioned rapidly and simply at the desired location using fixation pin applicator  22 . After fixation pin  20  has been positioned, in other words after points  26  of fixation pin  20  have engaged the cortex of bone  18  with a V-shaped portion of pin  20 , fixation pin  20  is secured to the clamping jaw as described above. After fixation pin  20  has been secured to the clamping jaw, fixation pin applicator  22  can be released from clamping jaw  10 , and the procedure can be repeated to position another clamping jaw  10  on bone  18 .  
         [0046]    Fixation pin applicator  22 , described with reference to FIGS. 1, 2,  10  and  11 , is designed in the shape of a pistol and has a fixed handle  28  and a housing  30  that resembles a pistol barrel. A piston or plunger  32  is located in housing  30 , said plunger being axially displaceable in the direction b indicated by the double arrow, said plunger acting on the fixation pin  20  inserted into fixation pin applicator  22 . Plunger  32  is displaceable by means of a transport plate  34 . This transport plate is impacted upon by a movable handle part  36  as the movable handle part is pivoted in the direction c indicated by the double arrow. This kinematic arrangement is apparent from a comparison of FIG. 1 showing handle part  36  in its initial position and FIG. 2 showing the handle part in its pivoted position.  
         [0047]    The operation of pin applicator  22  is conventional, and is designed to incrementally move plunger  32  towards passage  66 . For example, piston  32  abuts fixation pin  20 , which is loaded in hole  70  of clamping jaw  10 , and is kept in place within housing  30  by guide ways  72  as it is pushed towards bone  18 . A ratcheting mechanism, for example, can be used to allow motion of plunger  32  only in one direction, while fixation pin  20  is driven towards bone  18 . A release lever  38  is also mounted on fixation pin applicator  22 , said lever used to release piston  32  to pull it backwards, as shown in FIGS. 1 and 2.  
         [0048]    A pin  41  that is part of latching mechanism  24  engages a catch  64  formed in clamping jaw  10 . A bottom portion of clamping jaw  10  fits in an opening  66  of applicator  22 , as shown in FIGS. 1, 2,  9  and  10 . Once clamping jaw  10  is in position in opening  66 , pin  41  engages catch  64 , and keeps the two components attached. The fixation pin applicator can be released in simple fashion from clamping jaw  10  by actuating release lever  76 , which pulls pin  41  out of catch  64 .  
         [0049]    Thus, as shown in FIGS. 9, 10 and  11 , clamping jaw  10  is guided in opening  66  by guide ways  72 . Locking pin  41  is pushed by spring  74  towards catch  64  of the clamping jaw  10 , so that it automatically locks the clamping jaw in place once the jaw is positioned inside opening  66 . Locking pin  41  is moved away from catch  64  using pin release handle  76 , against the force of spring  74 , so that clamping jaw  10  can be released from housing  30 .  
         [0050]    In a different embodiment, locking pin  41  could be replaced by a spring loaded sphere, pressed against catch  64  with sufficient force to retain clamping jaw  10  in place in pin applicator  22 , while allowing separation of the two components if they are pulled apart. No actuator to release the two components is required for this embodiment.  
         [0051]    The operation of the fixation device according to the invention is described in the following, with reference to FIGS. 1, 2 and  7 . Clamping jaws  10  are initially fitted with the selected retaining pin  14 . Then the fixation pin applicator is connected to the clamping jaw, with a selected fixation pin  20  being inserted. This clamping jaw, provided with pins  14  and  20 , is placed over the portion of bone  18  where implantation is to occur and the appropriate perforations in the skin are marked. For each of the pins, or for each prong of the pins when applicable, a lengthwise incision approximately 8 to 10 mm long is made in the skin with a scalpel. The soft tissues are scraped away using a raspatory, and the bone is exposed down to the periosteum.  
         [0052]    The selected retaining pins  14 , attached to clamping jaw  10 , are then introduced into the soft tissues between the bone and the raspatory, until retaining pins  14  gain a sufficient grip in the vicinity of the rear edge of the bone  18 . Then fixation pin  20 , also connected to clamping jaw  10 , is introduced by means of fixation pin applicator  22  through the prepared skin incision in the area of the forward edge of the bone  18 , until proper bone contact is achieved. The implants are finally fixed in place by multiple actuation of handle  36 , which progressively pushes fixation pin  20  towards bone  18 . A sufficient grip of clamping jaw  10  is obtained when the injured extremity can be lifted at the clamping jaw from the support without the pins tearing loose. In the same fashion, the fragment opposite the fracture is secured with one or more clamping jaws  10 .  
         [0053]    When dual pins are used, it is sufficient to connect the clamping jaws located proximally and distally with respect to the fracture by means of sufficiently long rods. The fracture is repositioned, for example, while being viewed on an x-ray image converter. As soon as the fragments are in close proximity and the axes of the fragments have been aligned, final fixation of the rods is performed.  
         [0054]    It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Classification (CPC): 0