Abstract:
A mounting device for arranging a medical apparatus on a bone includes a fastening portion for fixing the mounting device to the bone. The fastening portion is configured to interface with the bone and operative to fix the mounting device to the bone using a vacuum.

Description:
RELATED APPLICATION DATA 
       [0001]    This application claims priority of U.S. Provisional Application No. 60/882,736 filed on Dec. 29, 2006, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to a mount for a bone drill and, more particularly, to a mount for a bone drill that is to be attached to the head of a femoral bone (Joint head). 
       BACKGROUND OF THE INVENTION 
       [0003]    In order to attach a femoral component of a leg bone during re-surfacing in hip surgery, the femoral bone is prepared such that it obtains a specific shape. While preparing the femoral bone, it is desirable to avoid any kind of notching or weakening of the joint neck, since such weakening or notching can cause cracks or fractures. 
         [0004]    A femoral implant component has a symmetrical inner shape with a central pin, and it is desirable to accurately define and realize the position and orientation of the hole for this central pin. During the re-surfacing treatment, a pilot drill hole is made for the central pin of the implant, and it is similarly desirable to place the pilot drill hole as accurately as possible, since all the subsequent working steps are based on this location. 
         [0005]    In order to support this drilling process, various tools have been used to define the entry point and the axis for the drill hole. U.S. Pat. No. 6,156,069 discloses a gripping device which grips the femoral neck and can guide the drill. U.S. Pat. No. 6,595,999 B2 discloses a drill mounting attached as a frame, in which a probe is provided in order to ensure positioning. Directing fastening to the femoral head or to a plane face of the femoral head, following a milling procedure, is also known from U.S. Pat. No. 6,595,999 B2. 
       SUMMARY OF THE INVENTION 
       [0006]    A bone drill mounting device in accordance with one aspect of the invention has a fastening portion for fastening to the bone. The fastening portion operates using vacuum suction. Thus, the fastening portion is fixed to the bone without having to encroach or otherwise damage the bone. This has various advantages. 
         [0007]    First, the mounting device allows a drill to be fixedly orientated, and the surgeon is able to make a drill hole in a defined direction. Since the mounting device fixes the drill to the bone, the risk of the drill slipping off the surface of the bone is significantly reduced. 
         [0008]    Also, no additional elements (pins, screws, grips, etc.) are necessary for attaching the mounting device to the bone. The stable connection to the bone is established by a difference in pressure; the drilling angle is similarly fixed in this way. Omitting screws or pins enables corresponding bone notches or bone damage (which can form the starting point for fractures or cracks) to be avoided. Further, avoiding the use of expendable products for fastening (e.g., bone screws or the like) lowers cost. Time is also saved, since establishing the vacuum merely involves suctioning off air, which in a suitable embodiment should transpire very quickly. Also, it is not necessary to additionally prepare the bone (for example by milling). The mounting device is simple and non-invasive to hand grip, and can very easily be combined with a navigation support, such that additional probes for verifying the orientation can likewise be omitted. 
         [0009]    The fastening portion of the mounting device can include a fastening vacuum space or fastening vacuum area, and a valve means via which the pressure in the fastening vacuum space or fastening vacuum area can be regulated. The fastening vacuum space can be sealed by a sealing means that grips and/or forms a seal with the bone, in particular by a sealing skirt array around the fastening vacuum space or fastening vacuum area. 
         [0010]    It is possible to arrange a drill guiding portion on the fastening portion, wherein the drill guiding portion can be moved relative to the fastening portion. The drill guiding portion can form an attachment that is sealed and can be shifted on the fastening portion, and which comprises a drill guide. The mounting device also can include a guiding vacuum space or guiding vacuum area that fixes the position of the drill guiding portion relative to the fastening portion when a vacuum is formed. 
         [0011]    The vacuum can be used in various ways. It is possible to connect the fastening and guiding vacuum spaces or vacuum areas to each other, such that they form a single vacuum area or vacuum space. In this case, establishing the vacuum would serve both to fasten the mounting device to the bone and to orientate and fix the drill guide. 
         [0012]    In another case, the vacuum spaces or vacuum areas for fastening and fixing could be separated from each other, such that the orientation of the drill can be performed independent of fastening the mounting device by applying separate vacuums. It is also in principle conceivable for only the drill guiding portion to be orientated and/or fixed using a vacuum. 
         [0013]    A separate valve means can be provided for the drill guiding portion, via which the pressure in the guiding vacuum space or guiding vacuum area can be regulated. 
         [0014]    A number of combinations of the bone drill mounting device with other medical apparatus or devices are envisioned. In particular, a bone drill mounting system can include a bone drill mounting device, such as has been described above in different embodiments, and a hand grip using which the mounting device can be held by means of a drill guide. The hand grip can be connected to a vacuum source and to the vacuum suction of the fastening portion, and in a specific embodiment, control devices for controlling the vacuum can be assigned to the hand grip. It is also possible to use the hand grip to control not only the suction of the fastening portion but also the fixing of the drill guiding portion by a vacuum, or one or both of these controls can be performed independently of each other. 
         [0015]    Another bone drill mounting system, including a bone drill mounting device as descried herein, also can include one or more of the following elements:
       a medical navigation reference arranged in a determined position relative to a drill guide which is assigned to the mounting device;   a medical navigation system that can ascertain the spatial position of the navigation reference;   a vacuum source connected to the vacuum suction of the fastening portion; and/or   control devices for controlling the vacuum in accordance with the spatial position of the navigation reference, and thus in accordance with the spatial position of the drill guide.       
 
         [0020]    The latter embodiment cited above thus enables the bone drill mounting device to be simply and directly incorporated into a medical navigation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0021]    The forgoing and other features of the invention are hereinafter discussed with reference to the drawings. 
           [0022]      FIG. 1  is a perspective view of an exemplary bone drill mounting device in accordance with the invention, arranged on a bone. 
           [0023]      FIGS. 2 to 4  illustrate exemplary bone drill mounting devices in a sectional view and arranged on the bone (femoral joint head); 
           [0024]      FIGS. 5 and 6  illustrate an exemplary bone drill mounting system in accordance with the invention, comprising a hand grip and vacuum source. 
           [0025]      FIG. 7  illustrates the incorporation of an exemplary mounting system in accordance with the invention into a medical navigation system. 
       
    
    
     DETAILED DESCRIPTION  
       [0026]    Each of  FIGS. 1 to 4  show an exemplary bone drill mounting device that as a whole bears the reference sign  10 . The bone drill mounting device  10  includes a fastening portion  1  that is placed over the joint head  7  of a femoral bone, which has not been treated. The bone is in contact only with sealing skirts  6 . A vacuum is formed in a circular space between the inner and outer skirt  6 , and holds the fastening portion  1  on the joint head  7 . The vacuum is indicated as a lower pressure in  FIG. 2  by P 1 , while the higher outer pressure is indicated by P 0 . The higher outer pressure P 0  presses the mounting  10  onto the joint head  7  until supporting pins  9 , only one of which can be seen in each of  FIGS. 2 to 4 , come to rest on the bone. 
         [0027]    The guiding portion  2  of the mounting device  10  can be placed on sealing rings  4  ( FIGS. 3 and 4 ) on top of the fastening portion  1 . The guiding portion  2  can be arranged such that it can be shifted, and two different positions are shown in  FIGS. 2 and 3 . Using this shifting arrangement, the drilling angle can be adjusted; by arranging the fastening portion  1 , the entry point can be selected and defined. 
         [0028]    The embodiment in  FIGS. 1 ,  2  and  3  has a single valve  5 , which can be used to suction air out of the vacuum space  19 , and in this embodiment, the fastening portion  1  is positioned in order to select the entry point, the guiding portion  2  is shifted and/or rotated until the entry angle is correct, and the vacuum is then applied via the valve  5 , which fixes both the fastening portion  1  and the guiding portion  2  such that drilling can be performed in a defined and correctly orientated manner. 
         [0029]    An embodiment which deviates slightly from this is shown in  FIG. 4 , wherein two vacuum systems are provided which are separate and operate independently of each other. One vacuum system charges the vacuum space  19  via the valve  5  to fasten the fastening portion  1 , and the second vacuum system charges the vacuum space  20  with a vacuum via the valve  8  to fix the guiding portion  2 . Fastening can therefore be performed independently of orientation of the drill  3 . 
         [0030]      FIGS. 5 and 6  show another exemplary bone drill mounting system. The mounting system of  FIGS. 5 and 6  include a vacuum source  14 , wherein  FIG. 6  provides a perspective view. The vacuum is generated directly and centrally in the corresponding spaces of the mounting via the drill guide  15 . The drill guide  15  is connected to a navigation reference  17 , which is discussed further below. The hand grip  18  comprising the two push buttons  11  and  12  is also attached to the drill guide, wherein the hand grip comprises a lead  13  to the vacuum source  14 . 
         [0031]    In this embodiment, a vacuum is for example generated or released again in the bone drill mounting  10  via the buttons  11  and  12 . The drill guide  15  can be orientated using the grip, before being fixed by applying the vacuum. 
         [0032]    The mounting system can be incorporated into a medical navigation system by means of the navigation reference  17  already mentioned above, as shown in  FIG. 7 , which shows how the navigation system  16  comprising tracking cameras (not indicated) is arranged such that it can determine the position and orientation of the navigation reference  17 . Once the correct position for the drilling guide  15  has then been found by means of the grip  18 , an automatic sequence can be performed, since, as shown, the navigation system  16  is connected to the vacuum source  14 . Thus, once the orientation of the drill guide  15  is correct, this can be confirmed by the navigation system  16  via the navigation reference  17 , and this confirmation can automatically trigger the suctioning of air from the mounting  10  via the drill guide  15 , the grip  18  and the lead  13  and with the aid of the vacuum source  14 . This ensures that the drill hole is made in precisely the orientation and position necessary to allow an implant to be optimally placed at a later time. 
         [0033]    Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.