Abstract:
An apparatus and method for preparing a tibia for knee surgery. The apparatus includes a tibial base having a center axis, and a handle coupled to the base at an anterior base location that is offset relative to the center axis.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an apparatus and method for tibial preparation. 
       BACKGROUND OF THE INVENTION 
       [0002]    During knee replacement surgery the tibial surface may be prepared for implantation of a tibial component of a knee implant. Several preparation instruments may be used to assist the surgeon in this procedure. A surgeon generally uses, for example, a tibial template and/or trial tibial tray to determine the tibial implant size, as well as various cutting, punching or reaming guides to make the appropriate cuts or reamed surfaces in the bone, and to ensure a proper alignment prior to implanting the tibial component. 
         [0003]    The tibial preparation procedure typically starts with making an initial tibial plateau cut on the proximal tibia of the knee joint. Using a tibial template, the size of the trial tray is then selected and placed over the resected surface of the tibia. After trial reduction, the trial tray is removed and a punch guide is placed on the resected tibial surface. The tibial bone is cut or reamed through openings in the punch guide and trial tray to prepare the bone to receive the tibial component of the implant. 
         [0004]    During the tibial preparation procedure, the surgeon may need to remove and reposition or re-orient a preparation instrument using a handle attached to the instrument. In the existing art, the handle is centrally attached to the instrument, and is often removed and re-attached, to avoid tissue impingement or provide clearance, for example. The prior art handle may obscure the view of the trial trays or guides and make alignment evaluation cumbersome, and generally reduces the manipulative clearance available to the surgeon. 
         [0005]    Accordingly, improved tibial preparation instruments that avoid some of the problems associated with the prior art handles are desirable. 
       SUMMARY OF THE INVENTION 
       [0006]    One embodiment of the invention provides an apparatus for preparing a tibia for knee surgery. The apparatus includes a tibial base having a center axis, and a handle coupled to the base at an anterior base location that is offset relative to the center axis. 
         [0007]    Another embodiment of the invention provides an apparatus for preparing a tibia for knee surgery. The apparatus includes a reversible base that is operable to engage in contact a surface of the tibia and has a center axis. The apparatus also includes a link coupled to the base at a position that is medially offset from the center axis. A handle is coupled to the link. 
         [0008]    Another embodiment of the invention provides an apparatus for preparing a tibia in knee surgery. The apparatus includes a tibial base having a center axis, and a handle coupled to the base at a first end. The first end has a medially offset cutout oriented to provided a lateral clearance relative to the center axis of the base. 
         [0009]    Another embodiment of the invention provides a method for tibial preparation for a knee implant procedure. The method includes selecting a tibial base, and coupling the tibial base with a handle at a position medially offset relate to a center axis of the tibial base. 
         [0010]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0012]      FIG. 1  is a perspective view of an embodiment of a tibial preparation apparatus according to the present invention, the apparatus shown in the environment of a right knee tibial bone. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    The following description of the embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0014]      FIG. 1  illustrates an embodiment for an apparatus  100  used to prepare a tibial surface  90  for knee surgery. The apparatus  100  is shown in the exemplary environment of a right knee tibial bone  80 . The apparatus  100  includes a tibial base  110 , a handle  120 , and a link  130 . The tibial base  110  can be a tibial template, a trial tibial tray or plate, a punching, reaming, cutting, or alignment guide or jig, or any other component that may be placed on the tibial surface  90  in preparation for knee replacement surgery. The tibial base  110  may be reversible in some embodiments, such as, for example when the tibial base  110  is a tibial template. The tibial base has a periphery  112  and a center axis “A”, which is generally, but not necessarily, an axis of symmetry of the tibial base  110 . The tibial base  110  may be temporarily secured to the tibial surface  90  with pins (not shown) inserted through fixation holes  140 . The center axis A may lie on the median plane of the tibia  80  when the tibial base  110  is positioned on the tibial surface  90 . 
         [0015]    The handle  120  is an elongated member that may include a longitudinal slot  122  to provide weight reduction to the apparatus  100  without compromising its strength. The handle  120  may include one or more sleeves  124  for inserting alignment rods, such as rods or pins or drill bits for setting rotation along the tibial tubercle or second metatarsal, for example. The handle  120  has a proximal end  126 , a distal end  128 , and a longitudinal axis “B” which coincides with the center axis A of the tibial base  110  when the handle  120  is attached to the tibial base  110 . The handle  120  is used to conveniently move the base  110  relatively to the tibial surface  90 , but it can also be used to verify rotational, varus/valgus, and flexion/extension alignments, for example. 
         [0016]    Although the handle  120  may be centered about the center axis A of the tibial base  110 , such that the longitudinal axis B of the handle coincides with the center axis A of the base  110 , at least a partial offset in the medial direction (“medial offset”) is provided at the base-handle connection. The medial offset, generally designated as  150 , may be constructed by a variety of structures in combination with a handle  120  that is integral to the base  110 , or a modular handle  120  that can be removably attached to the base  110 , or with a link  130  used as an intermediate structure between the base  110  and the handle  120 . 
         [0017]    In one embodiment, the link  130  extends from a medially offset anterior position  160  on the periphery  112  of the base  110 , and couples the base  110  to the proximal end  126  of the handle  120 . The link  130  has a center axis C which is medially offset from the axis A at an angle β, which provides a measure for the medial offset  150 . The angle β may be, for example, about 15° to about 45° degrees. 
         [0018]    The medial offset  150  provides a desirable clearance that helps avoid lateral tissue impingement during the tibial preparation procedures, which include trial sizing, alignment, punching, reaming, cutting, etc. Furthermore, the medial offset  150  enhances the visibility of the tibial base  110 , the periphery  112  of the tibial base  110  and the tibial bone  80 , and also provides manipulative clearance for the surgeon. 
         [0019]    The link  130  may include a curved portion  132  which provides a smooth transition between the base  110  and the handle  120 . The link  130  may be modular, or integral to the base  110 , or integral to the handle  120 . Accordingly, the link  130  can be removably coupled to the base  110  or to the handle  120  or to both. In another embodiment, the handle  120  is directly coupled to the tibial base  110  at the medially offset anterior position  160  and includes a cutout that defines the medial offset  150 . 
         [0020]    In operation, the apparatus  100  is selectively placed on the tibial surface  90 , such that the medially offset position  160  is on the medial and anterior side of each knee. For a reversible base  110 , this is accomplished by rotating the apparatus  100  by 180° for use from a right knee to a left knee, and conversely. In applications in which the tibial base  100  is not reversible, two mirror image apparatuses  100 , one for each knee, can be provided. 
         [0021]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.