Abstract:
A surgical driver including an open frame and a plurality of drive shafts rotatably routed in said open frame.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains generally to surgical instruments and, more particularly, to surgical instruments such as surgical tool drivers suited for use in orthopeadic surgical procedures. 
     2. Description of the Related Art 
     An orthopeadic driver assembly can be used to ream or cut a bone and thereby form the bone into a predetermined shape for receiving an orthopeadic implant. For example, an orthopeadic reamer assembly may be used to shape the interior or exterior surface of a bone. A rotary tool provides the rotational force and is connected to the driver, which is connected to the reamer. The driver generally has a shaft end and a drive end. The reamer may have a typically hemispherical shape and be attached to the drive end of the driver at the base of the hemisphere. The face of the reamer has a shape, which corresponds to the shape of an orthopeadic implant to be received within the bone, and includes a plurality of cutting teeth extending from the distal face. The reamer is positioned, oriented and placed against the bone surface to be cut, such as an acetabulum or glenoid and is plunge cut into the bone. The use of the reamer in this manner effectively removes a portion of the bone so that the bone is shaped to receive the implant. 
     Minimally invasive surgery reduces the size of the incision site so as to reduce trauma to the patient leading to reduced recovery time. Orthopeadic reamers have been designed for minimally invasive surgery, such as U.S. patent application Ser. No. 10/659,812, assigned to the assignee of the present invention. There are known orthopeadic drivers, which have flexible shafts. Flexible shafts allow the reamer to travel along a path in a non-linear manner resulting in a less than desirable opening in the bone. 
     What is needed in the art is a driver shaped for use in a minimally invasive surgical application that is cost effective to manufacture and maintain. 
     SUMMARY OF THE INVENTION 
     The present invention provides a driver that holds a drive head in a fixed position with the drive train being routed in a manner non-axial with the drive head. 
     The invention comprises, in one form thereof, a surgical driver including an open frame and a plurality of drive shafts rotationally routed in the open frame. 
     An advantage of the present invention is that the open frame allows for easy maintenance and cleaning of the driver. 
     Another advantage of the present invention is that it is easily disassembled for cleaning. 
     Yet another advantage of the present invention is that the removable input shaft readily mates with the drive shaft that is pinned to other link members. 
     Still another advantage of the present invention is that the axis of the output shaft is offset from the input axis of the driver. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an embodiment of a minimally invasive surgical driver of the present invention; 
         FIG. 2  is a side view of the driver of  FIG. 1 ; and 
         FIG. 3  is an exploded of the driver of  FIGS. 1 and 2 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and, more particularly to  FIGS. 1-3 , there is shown an embodiment of a surgical driver assembly  10 , which includes a handle assembly  12 , a drive body  14 , a drive train assembly  16  and a drive head  18 . Handle assembly  12  includes an axial opening  20  and a radial opening  22  in which a pushbutton  24  and biasing device  26  is associated. A transition collar  28  interfaces with a portion of frame  14  and an end of handle  12  to secure frame  14  to handle  12 . Transition collar  28  includes a groove  30 , which interfaces with pushbutton  24  such that handle assembly  12  is connected to the rest of driver assembly  10  until pushbutton  24  is depressed against biasing device  26 , thereby moving a feature in pushbutton  24  away from groove  30  allowing handle  12  to be removed from transition collar  28 . This allows for quick disassembly of driver assembly  10  so that individual items may be maintained and/or cleaned. 
     Drive body  14 , also known as an open frame  14  includes end openings  32  and  34  through which drive shafts are positioned in order to rotatably drive, drive head  18 . Open frame  14  also includes a side opening  36 , which is substantially the full length of frame  14 . Side opening  36  extends completely through frame  14  and openings  32  and  34  open thereinto. 
     Drive train assembly  16  includes six drive shafts, and more particularly an input shaft  38 , a drive shaft  40 , a drive shaft  42 , a drive shaft  44 , a drive shaft  46 , and an output shaft  48 . Input shaft  38  traverses axial opening  20  of handle assembly  12  and either has a drive end formed on one end of shaft  38  or interfaces with a drive end  58 . Another end of input shaft  16  includes slots  50 , which are shown as two slots with angled portions which are formed to direct a blade  52  on drive shaft  40  into one of slots  50 . The angled feature of slots  50  advantageously allow input shaft  38  to be inserted without the need of orienting shaft  38  since shaft  38  will self-align as it encounters blade  52 , thereby positioning blade  52  in one of slots  50 . As would be understood by those in the art, the features described on shafts  38  and  40  could be reversed to achieve the same function. Shafts  40 ,  42 ,  44 ,  46  and  48  each have a constrained substantially spherical element having a hole therethrough in order to facilitate a connection between each of shafts  40 - 48  by way of pins  56 . A pin  56  is inserted through one end of each of shafts  42 - 48  to rotatably fix each respective shaft to a previous shaft. Prior to inserting pins  56 , shafts  42  and  46  are inserted into blocks  54  and blocks  54  are positioned and pinned into place in open frame  14 . Shaft  44  is constrained by the relative end positions of shafts  42  and  46  and is not otherwise constrained with any blocks such as blocks  54 . As can be seen in  FIG. 2 , shaft  44  is only constrained in the position shown by being connected to shafts  42  and  46 . Further, in  FIG. 3  it can be more specifically seen that the constraint of shaft  44  to shaft  42  is by way of a pin inserted along axis  66 , and shaft  44  is constrained to shaft  46  by way of another pin inserted along axis  68 . As can be seen in  FIGS. 2 and 3  that other than driving connections to shaft  44  there are not any contacting constraints. Output shaft  48  is pinned to drive shaft  46  at one end thereof. Another end of output shaft  48  interface features that are formed therein to engage drive head  18  in order to allow a transfer of rotational movement from input shaft  38  through output shaft  48 . Output shaft  48  is connected to a tool such as a bit or reamer for the removal of bone. 
     Input shaft  38  rotates about a rotational axis  60  and is driven by a rotational power tool, not shown. At an opposite end of drive assembly  10  output shaft  48  rotates about a rotational axis  62  with axises  60  and  62  being offset from each other and generally parallel to each other. The offset of rotational axis  62  from rotational axis  60  occurs because the length of drive shaft  46  is different than the length of drive shaft  42  with the angles of frame  14  being substantially complimentary. The longer length of drive shaft  46  causes rotational axis  62  to be offset from rotational axis  60 . 
     Another feature of the present invention includes the positioning of pins  56  relative to each other. Shafts  40 - 48  are aligned such that pins  56 , which connect shafts  40 - 48  together are not aligned. For example, shafts  42  and  44  have a pin  56  oriented along an interconnect axis  64  and shafts  44  and  46  are connected along an interconnect axis  66 . Likewise, shafts  46  and  48  are interconnected along an interconnect axis  68 . Interconnect axis  64  and interconnect axis  66  are shown here as being offset rotationally by 90° from one end of shaft  44  to the other end of shaft  44 . In a rotational sense interconnect axis  68  is shown as being substantially parallel to interconnect axis  64 . While this is shown in this manner it can also be understood that each of the interconnect axis  64 - 68  and any others within drive train  16  may be all offset from each other. It has been known that interconnections such as those between adjacent shafts will sometimes exhibit a phenomenon in which there is a non-uniform rotation with a slight acceleration and deceleration at certain points in the rotation of the shafts. By offsetting the interconnect axis the present invention advantageously reduces any amplification that may exist if interconnect axis were aligned. 
     Advantageously the present invention is shaped to allow its use in minimally invasive surgery techniques. Additionally, the open access of the drive shafts allows for ease of maintenance and cleaning of the individual parts. Additionally, the present invention allows for easy disassembly of the unit and includes features of self-alignment when the unit is reassembled. Further, interconnections are offset to minimize any surges in radial velocity caused by the linkages. Yet a further advantage of the present invention is that the input and output rotational axis are offset and substantially parallel to each other, thereby allowing the surgeon to take advantage of an offset in the rotational axis during the operational procedure. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.