Abstract:
An apparatus and method for implanting a prosthesis includes implanting a first component into a recess in a bone. The first component defines a main body defining a receiving portion and a locating bore. A second component is located into engagement with the first component, the second component defining a passage therethrough. A rod is inserted through the passage defined on the second component and into the locating bore of the first component. A handle associated with the rod is slidably actuated into contact with the second component to matingly lock the first component to the second component.

Description:
FIELD OF THE INVENTION 
     The present invention relates to assembling implants and more particularly to in-vivo assembly of a tibial tray. 
     BACKGROUND OF THE INVENTION 
     A knee joint prosthesis typically comprises a femoral component and a tibial component. The femoral component and the tibial component are designed to be surgically attached to the distal end of the femur and the proximal end of the tibia, respectively. The femoral component is further designed to cooperate with the tibial component in simulating an articulating motion of an anatomical knee joint. 
     In one application, a tibial component includes a modular tibial tray connected to a modular tibial stem and implanted at the proximal tibia. Typically during a tibial preparation procedure, portions of the proximal tibia may be resected to define a surface for accepting the tibial tray. In addition, a recess may be prepared in the tibial bone to accept the tibial stem. Typically, the tibial stem is assembled to the tibial tray ex-vivo prior to implanting onto the proximal tibia. In one example, a mallet is used to couple the tray to the stem. 
     In some instances it is inconvenient to couple implants such as the tibial tray to the tibial stem ex-vivo prior to implanting with a given bone such as on a proximal tibia. What is needed is a system for providing convenient and robust in-vivo assembly of implants. 
     SUMMARY OF THE INVENTION 
     An apparatus and method for implanting a prosthesis includes implanting a first component into a recess in a bone. The first component defines a main body defining a receiving portion and a locating bore. A second component is located into engagement with the first component, the second component defining a passage therethrough. A rod is inserted through the passage defined on the second component and into the locating bore of the first component. A handle associated with the rod is slidably actuated into contact with the second component to matingly lock the first component to the second component. 
     According to other features, the receiving portion of the first component defines tapered sidewalls. The insertion portion defines tapered sidewalls for mating with the tapered sidewalls of the receiving portion. The locating bore of the first component is centrally positioned on the main body portion and substantially parallel to a longitudinal axis of the bone. The distal end of the rod is threaded for threadably mating with the locating bore. The rod includes a stopping member arranged on a proximal end. The handle is bound between the stopping member and the second component during slidable actuation. 
     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 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a slaphammer according to the present teachings; 
         FIG. 2  is a sectional view of the slaphammer of  FIG. 1  shown implanting a tibial tray with a tibial stem into a proximal end of a tibia; 
         FIG. 3  is a plan view of the tibial tray of  FIG. 2 ; 
         FIG. 4  is an exploded assembly view of the slaphammer and tibial tray shown prior to engagement with the tibial stem; and 
         FIG. 5  is a perspective view of the slaphammer shown with the tibial tray received by the tibial stem after sufficient actuation of the slaphammer during assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For example, while the following discussion is specifically directed toward implanting a tibial tray with respect to a tibial stem onto a proximal tibia, it is appreciated that the present teachings are not so limited. In this way, the present teachings may be similarly directed toward in-vivo assembly of other implants where relative coupling between two components of any type of implant assembly is needed. 
     With initial reference to  FIG. 1 , a slaphammer for in-vivo assembly of implants according to the present teachings is shown and generally identified at reference  10 . The slaphammer  10  generally includes a rod  12  having a threaded portion  14  arranged on a distal end  18  and a stopping member  20  arranged on a proximal end  24 . A handle  28  is adapted for slidable communication along the rod  12 . As will be explained more fully in the discussion below, the slaphammer  10  is operable to facilitate in-vivo assembly of implants, such as complementary implants. 
     With continued reference to  FIG. 1  and further reference to  FIG. 2 , the slaphammer  10  will be described in greater detail. It is appreciated that while the rod  12  is shown to have a rectangular cross section on the proximal end  24  and a circular cross section on the distal end  18 , the cross sections are merely exemplary. An inner passage  30  is defined axially through the handle  28  of the slaphammer  10  for slidably accepting the rod  12  therethrough. The handle  28  includes a distal end portion  34 , a proximal end portion  36  and an intermediate portion  38 . The distal end portion  34  is adapted to impart a blow onto the surface of an implant as will be described. The proximal end portion  36  of the handle  28  is bound by the stopping member  20  during slidable actuation along the rod  12 . The intermediate portion  38  includes a series of ergonomic groove portions  40  formed radially around an outer surface for providing a favorable gripping surface. 
     With continued reference to  FIG. 1  and further reference to  FIGS. 2 and 3 , the slaphammer  10  is shown operatively associated with a knee joint prosthesis  42 . Again, the slaphammer  10  can be used to assemble any type of implant having multiple components that required attachment to one another using any type of attachment mechanism, such as for example a Morse taper connection. The knee joint prosthesis  42  is shown being secured to a tibia  44  of a surgically resected left knee joint, with the tibia  44  shown in phantom, and with the understanding that a suitable right knee joint prosthesis can be similarly constructed. The knee joint prosthesis  42  generally may include a tibial component  46  having a floating tibial bearing  48 . While not specifically shown, the tibial bearing  48  may be located between the tibial component  46  and a femoral component secured to a distal end of a femur. 
     The tibial component  46  is adapted to be secured to the proximal end of the tibia  44  after the tibia  44  has been resected in a manner known in the art. The tibial component  46  includes a substantially planar platform-like tibial tray  50  and an inferiorly extending tibial stem  52 . The tibial tray  50  includes an upper bearing surface  54 . The tibial stem  52  is adapted to be received in a corresponding opening made by the surgeon in the intramedullary canal of the tibia  44 . The tibial tray  50  defines a male extension portion  56  for being accepted into a complementary female receiving portion  60  according to the present teachings as will be described in greater detail herein. The male extension portion  56  includes a conically tapered sidewall  62 . The female receiving portion  60  defines a conically tapered bore  64 . The conically tapered sidewall  62  is operable to be nestingly received within the conically tapered bore  64  to provide a friction fit that forms a Morse-type taper. It is appreciated that the respective male extension portion  56  and female receiving portion  60  may be reversed. 
     A central passage  68  is defined through a central body portion  70  of the tibial tray  50  for passing the rod therethrough during assembly of the tibial tray  50  onto the tibial stem  52 . A locating bore  74  having threads is defined inferiorly of the stem  52  at a terminal surface of the female receiving portion  60  for accepting the distal end  18  of the rod  12 . The tibial tray  50  and tibial stem  52  are preferably manufactured from cobalt-chromium-molybdenum or any other suitable biocompatible material. The top of the tibial tray  50  provides a substantially smooth tibial bearing surface. 
     With further reference now to  FIGS. 4 and 5 , assembly of the tibial stem  52  and tibial tray  50  onto a proximal end of the tibia  44  will be described. Initially, the tibial stem  52  is placed into the opening made by the surgeon in the center of the tibia  44 . It is appreciated that the upper surface of the tibial stem  52  may be left proud with respect to the proximal surface of the tibia  44  or alternatively be flush with the proximal surface of the tibia  44 . Next, the tibial tray  50  is set onto the tibial stem  52 . In this regard, the male extension portion  56  is aligned axially with the female receiving portion  60  and advanced downwardly (as viewed from  FIG. 4 ) until the respective conically tapered sidewalls  62  and  64  engage. 
     At this point, the distal end  18  of the rod  12  is passed through the passage  68  of the tibial tray  50  and engaged with the locating bore  74 . It is appreciated that the distal end  18  of the rod  12  may be initially passed through the passage  68  of the tibial tray  50  subsequent to locating the tibial tray  50  onto the tibial stem. The locating bore  74  acts to orient the rod  12  in a generally transverse relationship with the tibial tray  50 . In the exemplary illustrations provided, a threadable interface  78  is provided between the distal end  18  of the rod  12  and the locating bore  74 . As a result, the transversely extending stopping member  20  may be grasped and rotated about an axis of the rod  12  to impart sufficient torque at the threaded interface  78 . It is appreciated that while threads  14  are shown associated with the distal end  18  of the rod  12  and incorporated on the locating bore  74  for achieving an engaged relationship between the rod  12  and the locating bore  74 , other mechanical configurations may be employed, such as for example spring loaded locking tabs, magnetic interface or any other suitable coupling interface. Alternatively, the distal end  18  of the rod  12  and the locating bore  74  may each present a smooth surface without providing any relative coupling action. 
     Next, the male extension portion  56  of the tibial tray  50  is driven into engagement with the female receiving portion  60  of the tibial stem  52  by slidable actuation of the handle  28 . Explained further, while holding the stopping member  20 , the handle  28  is driven linearly along the rod  12  such that the distal end portion  34  impacts the upper bearing surface  54  of the tibial tray  50 . The impacting force causes the tibial tray  50  to slidably engage with the stem  52  along respective tapered sidewalls  62  and  64 . In some instances a single blow with the handle  28  may cause the male extension portion  56  to sufficiently nest within the female receiving portion  60  such that the tibial tray  50  is flush with the proximal tibia ( FIG. 5 ). In other instances, it may be necessary to strike one or more subsequent blows onto the tibial tray  50  with the handle  28 . As such, the handle  28  is advanced along the rod  12  in a direction away from the tibial tray  50 . The handle  28  may be advanced into engagement with the stopping member  20  or to a position along the rod  12  a distance from the tibial tray  50 . The handle  28  is then driven into impact with the tibial tray  50  as previously described. These steps are repeated as necessary until the tibial tray  50  achieves a desired relationship with the tibial stem ( FIG. 5 ). Finally, the rod  12  is retracted from the locating bore  74 . This step may include threadably retracting the rod  12  from the threads of the locating bore  74 , or disengaging a coupling interface employed at the distal end  18  of the rod  12  and the locating bore  74 . It is appreciated that in some instances, the slaphammer  10  may be removed once the respective tapered sidewalls  62  and  64  achieve partial engagement. Subsequent to removal of the slaphammer  10 , the tibial tray  50  may be further seated onto the proximal tibia such as by a mallet or other impacting instrument. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. For example while the description herein relates to implanting a tibial tray, the slaphammer may be used for implanting associated with a femur, a hip, and a shoulder for example. In this way, the slaphammer may be used to facilitate in-vivo assembly at the implant site whereby a first component is located at the implant site and a second component is introduced and subsequently coupled to the first component. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.