Patent Document

The present application claims the benefit of prior filed U.S. Provisional Patent Application Ser. No. 60/871,300 filed 24 Dec. 2006, the content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is in the field of orthopedic surgical instrumentation (class 606/53). Specifically, the present invention relates to surgical instrumentation for use in bone preparation for the manipulation, placement or removal of an internal bone prosthesis (class 606/53; 86). More specifically, the present invention relates to prosthesis inserters, such as impactors, adapted to place or remove a bone repairing means through forceful contact, in which momentum is transferred from the force transferring means to the preparation means (class 606/53; 86; 99). 
     BACKGROUND OF THE INVENTION 
     Surgical procedures for the implantation of orthopedic prosthetic assemblies often requires specialized tools specifically adapted for insertion of a particular component of the prosthetic assembly. In the field, a number of different inserter handles for use in a surgical procedure to hold and manipulate a prosthesis component during its implantation in a patient are described. Typically, inserter handles have a front end (mount end) adapted to receive and hold a particular prosthesis component during implantation, and to release the component upon completion of its installation. An example of such an existing inserter handle is described in WIPO Publication Number WO 2005/044153 to Lechot &amp; Desarzens, the content of which is incorporated herein by reference. 
     In this type of inserter handle, the mount end is adapted to releasably mate with a prosthesis component via a threaded interface. The action for achieving the threaded interface between the mount and the component of the prosthetic assembly is accomplished using a screw knob disposed at the impactor end of the inserted handle. Rotating the screw knob rotates the threaded interface at the mount end of the inserter handle to securely engage or disengage the prosthetic component. In practice, the prosthetic component is first securely screwed to the mount end of the inserter handle by the user rotating the screw knob. The combination of the inserter handle with the prosthetic component attached is used to seat the prosthetic component at its intended implantation site in the patient utilizing the impactor feature/function of the inserter handle. Once the prosthetic component is seated in a proper relationship in the installation site in the patient, the user counter-rotates the screw knob to disengage the threaded interface of the mount end from the prosthetic component, and the inserter handle is removed from the patient leaving the component in situ. 
     A disadvantage of this practice is that, once the proper relationship of the prosthetic component is achieved in the installation site, it is necessary as well to hold the positional relationship of the inserter handle relative to the installation site during the disengagement of the threaded interface of the mount end from the prosthetic component. Holding this positional relationship during disengagement can be problematic (e.g., because of the relatively substantial mass and length of the inserter handle, the time and amount of manipulation required to reverse the securely threaded interface, etc.). Therefore, it would be advantageous to the field to have an interface between the inserter handle and the prosthetic component that is quickly disengageable and requires little manipulation to accomplish. Additionally, it would be beneficial to have an interface that could accommodate a variety of prosthetic component configurations for combination with a given inserter handle. 
     SUMMARY OF THE INVENTION 
     The present invention is a mount adaptor/holder that is attachable to the mount end of an existing inserter handle, which adapts the inserter handle to quickly engage and disengage a component of an orthopedic prosthesis assembly. An example of an orthopedic prosthesis assembly is an artificial ball and rotator cup joint, comprising a ball prosthetic component receivable in a rotator cup prosthetic component. Such orthopedic prosthesis joint assemblies are known in the art. 
     The present adaptor/holder is designed to attach to the mount (or tool) end of an inserter handle via an existing threaded interface mechanism of the handle. The adaptor/holder then utilizes the inserter handle&#39;s existing mount tensioning mechanism to accomplish the quick engagement and disengagement of a component of an orthopedic prosthesis assembly. Upon activation of the inserter handle&#39;s tensioning mechanism, the adaptor mount receives and fixes a prosthetic component to the tool end of the inserter handle for use. Deactivation of the inserter handle&#39;s tensioning mechanism is quickly accomplished with minimal manipulation to rapidly release the prosthetic component. In the cases illustrated herein, the prosthetic component to be installed is a cup insert. 
     An important feature of the present prosthetic component holder is that it enables the prosthetic component to be detached from the inserter handle, in situ, without having to operate the drive assembly of the handle to release the component after its installation in a patient. This feature of the present holder and handle combination eliminates the need for a threaded interface on the prosthetic component. A benefit of this feature is that, unlike prior inserter devices, the entire instrument (the handle with the holder still attached) can be quickly removed from the surgical site without having to maintain the positioning of the handle relative to the prosthetic component (e.g., an insert cup) inside the patient. That is done by unscrewing the drive linkage assembly to separate the handle from the insert cup. Additionally, in prior inserter handles, where the inserted cup is screwed to the tool end of the drive linkage, unscrewing the drive linkage assembly can apply rotational torque to the installed prosthesis cup, which can potentially cause the cup to move from its set position or even to become dislodged. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a prior impactor-type inserter handle with a prosthetic component mounted on its front end. 
         FIG. 2  is a perspective drawing showing the tool attachment end of an inserter handle, the attachment end being able to mount an interchangeable nose or the prosthesis component holder of the present invention. 
         FIG. 3  is an exploded perspective view of components of the present prosthesis component holder. 
         FIG. 4A  is a partial cross-sectional view of the present holder mounted to the tool end of an inserter handle with a prosthesis component (a cup insert in the figure) positioned to be attached to the holder. 
         FIG. 4B  is a perspective view of the present holder mounted to the tool end of an inserter handle with a prosthetic cup insert positioned to be attached to the holder before actuation of the holder, and showing the normal relationship of the component parts of the holder. 
         FIG. 4C  is a partial cross-sectional view of the present holder mounted to the tool end of an inserter handle after actuation of the holder, and showing the relationship of the component parts of the holder when actuated to secure the prosthesis component in position on the holder. 
         FIG. 4D  is a partial cross-sectional view of the present holder mounted to the tool end of an inserter handle with a prosthesis component attached to the holder. 
         FIGS. 5A to 5C  illustrate cooperation of the present holder with an existing inserter handle and (A) attachment of the holder to the inserter handle, (B) interfacing of the draw piston of the inserter handle&#39;s drive assembly to the coupling mechanism of the holder, and (C) actuation of the draw piston to secure the prosthesis component to the holder, and the holder to the tool boss of the inserter handle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, the details of preferred embodiments of the present invention are graphically and schematically illustrated. Like elements in the drawings are represented by like numbers, and any similar elements are represented by like numbers with a different lower case letter suffix. 
     As shown in  FIG. 2 , the present invention is a prosthesis component holder  40  attachable to the mount/tool end  17  of an existing inserter handle  10  (see  FIG. 1 ). The inserter handle  10  has a draw piston  20  projecting through the drive end boss  18  at its mount end  17 . The draw piston  20  is operated by the lever action of the drive chain shaft  34  of the handle  10 . The holder  40  comprises an annular housing  42  attachable to the drive end boss  18  of the inserter handle  10 . The housing  42  has several surfaces including: a front surface  44 , a back surface  46 , an outer surface  48  and an inner surface  50 . The inner housing surface  50  defines an annular opening  54  in the housing  42 . The annular opening  54  has a central annulus axis  56   
     As also illustrated in  FIG. 2 , an attachment mechanism  58  is disposed on the inner surface  50  of the housing  42  proximate the back surface  46 . The attachment mechanism  58  is disposed to mate with a complimentary mating mechanism  23  at the drive end boss  18  (see  FIG. 3 ). The attachment mechanism  58  releasably attaches the present holder  10  to the drive end boss  18  of the handle  40 , so that back surface  46  of the housing  42  contacts the attachment interface  16  of the drive end boss  18 . In the embodiment illustrated, the attachment mechanism  58  comprised a circumferential groove  60  on the inner surface  50  of the housing  42  proximate the back surface  46 , into which groove  60  a snap-ring  62  was received. The complimentary mating mechanism  23  on the drive end boss  18  is a complementary circumferential detent groove on the barrel  26  of the drive end boss  18 . Other complementary mechanisms  58  and  23  are known to and selectable by the ordinary skilled artisan for practice in the present invention. For example, a pin and “J”-groove or bayonet mechanisms can be used. However, the snap-ring and detent combination illustrated for attaching the holder  40  to the drive end boss  18  has the advantage, as explained later, of allowing the holder to be rotationally oriented on the drive end boss  18  after attachment. 
     A cavity  66  is set into the front housing surface  44  of the housing  42 . The cavity  66  communicates with the annular opening  54 , and is a widening of the annular opening  54  disposed to receive the coupling mechanism  70  of the holder  40 . The coupling mechanism  70  has a coupling yoke  72  slideably receivable into the cavity  66 . The yoke  72  itself has a yoke bore  74  with a central yoke axis  76 . The yoke  72  is slidably (and in the embodiments illustrated, rotatably) received within the cavity  66 , and disposed to provide that the axis  76  of the yoke  72  is held substantially coaxial with the annulus axis  56  of the housing  42 . 
     In the embodiments illustrated, two yoke linkages  80  pivotably connect the yoke  72  to the housing  42 . Although two are shown, it is anticipated that only one such linkage is necessary to provide for satisfactory precision and performance of the coupling mechanism. However, it is clear to one of skill in the art that three or more such linkages could be practiced as well. In the present embodiment, each yoke linkage  80  included a link member  82  connected at a first link end  84  to the yoke  72  by a sliding pivot coupling  86  and at a second end  92  to the housing  42  by a simple pivot coupling  94 . The couplings  86  and  94  each have a pivot pin  90 . In the simple coupling  94 , the pivot pin  90  passes through a clearance aperture  96  in the second end  92  of the link member  82 , to be fixedly received in a pivot pin hole(s)  98  in the yoke  72 . In the sliding coupling  86 , the pivot pin  90  passes through a clearance slot  88  in the first end  84  of the link member  82 , to be fixedly received in a pivot pin hole(s)  98  in the housing  42 . The pivot pins  90  and pin holes  98  in the illustrated embodiment are friction/wedge fitted together. However, the ordinary skilled artisan knows how to select and substitute other pivot coupling equivalents to these and anticipated by the present invention, such as screw pins and threaded pivot pin holes. 
     A prosthesis contacting face  100  is disposed on each link member  82 . The prosthesis face  100  is disposed to normally interface with a mounting surface  112  of prosthesis component  12  to be secured by the holder  40 , and a drift pin  102  is fixed to the link member  82  and projects perpendicularly from the prosthesis face  100  relative to the drift axis  104  of the drift pin  102 . The length L that the drift pin extends beyond the prosthesis face  100  is important, and is chosen as noted below. 
     As illustrated in  FIG. 4A , a travel limiter mechanism  106  is associated with at least one yoke linkage  80 . In the preferred embodiment illustrated, both linkages  80  had a travel limiter mechanism  106 . The travel limiter  106  comprised a limit set pin  108  mounted in the housing  42  proximate the simple pivot coupling  94  and projecting into the coupling toward the second end  92  of the link member  82  to limit the degree of rotation of the link member  82  around the pivot pin  90  of the simple coupling  94 . Travel limit is accomplished when the stop seat  110  on the link member  82  contacts the limit set pin  108 , preventing the link member  82  from rotating further around the pivot pin  90 . Although not shown, the limit set pin  108  can be a set screw received in a threaded set bore  109  (for example, with a locking insert (not shown)). This combination allows the limitation of the degree of rotation of the link member  82  around the pivot pin  90  of the simple coupling  94  to be more readily adjustable than might otherwise be accomplished. 
     A biasing mechanism  116  is disposed within the cavity  66 , and applies a force to the yoke  72  to slide the yoke  72  out of the cavity  66 . Although, the biasing mechanism  116  in the embodiments illustrated was a single coil helical spring, other biasing mechanisms are anticipated for practice in the present invention. For example, multiple springs or resilient pads can be used. The movement of the yoke  72  out of the cavity  66  acts via the linkages  70  to hold the stop seat  110  of the link member  82  against the limit set pin  108  of the travel limiter  106 . By this action, the angular relationship drift axis  104  of the drift pins  102  is set to normally be substantially parallel with each other and with the yoke axis. In this configuration, the drift pins  102  are disposed to be received into drift receivers  114  in the mounting surface  112  of the prosthesis component  12 . 
     As shown in  FIGS. 3 and 4A , an actuator interface  120  is disposed at the yoke bore  74  of the yoke  72 . The actuator interface  120  mechanically connects the coupling mechanism  70  to the draw piston  20  of the inserter handle  10 . In the embodiment illustrated, the actuator interface is a threaded receiver in the yoke bore  74  that mates with the threaded interface  22  on the handle draw piston  20  (see  FIG. 2 ). As a result of this arrangement, operation of the draw piston  120  overcomes the normal bias force of the biasing mechanism  116 , and draws the yoke  72  of the coupling assembly  70  into the cavity  66 . This action causes the link members  82  to rotate on the pivot couplings  94 , and concomitantly change the angular relationship of the drift axis  104  drift pins  102  to be progressively more acute (see  FIG. 4C ), and results in a pincer action of the drift pins  102  in the drift pin receivers  114  of the prosthesis component  12 . 
     As shown in  FIGS. 4C and 4D , when a prosthesis component  12  is positioned on the holder  40  (see  FIG. 4B ), the pincer action of the drift pins  102  in the drift receivers  114  draws the mounting surface  112  of the component  12  securely against the front surface  44  of the housing  42 . Further, the action of drawing the yoke  72  into the cavity  66  applies a force on the housing  42  which drives the back housing surface  46  against the attachment interface  16  of the drive end boss  18  and secures the housing  42  as well to the drive end boss  18  of the inserter handle  10 . 
       FIGS. 4C and 4D  also illustrate an alternative configuration of the drift receivers  114 a. In this configuration, the receiver  114   a  has an engagement shoulder  115  to facilitate the pincer action of the drift, pins  102  upon actuation of the holder. A further alternative feature of the present invention illustrated in the figure is the ability to rotate the holder  40  relative to the drive end boss  18  of the inserter handle  10  within a limited range. This is accomplished by the interface surface  16   a  of the drive end boss  18   a  having rotation stops  130  projecting from the surface  16   a  into arcuate limit slots  132  set in the back surface  46  of the housing  42 . The radius of the arc of the limit slots  132  corresponds to the radial distance of the rotation stop  130  from the annular axis  56 . In this embodiment, once the holder  40  is attached to the drive end boss  18  using the snap-ring and detent attachment mechanism  58  illustrated in the figures, the holder  40  may by rotated within the limits permitted by the interaction of the rotation limit slots  132  with the rotation stops  130 . Although, two rotation stops  130  and two limit slots  132  are illustrated, practicing only one stop  130  and one slot  132  is anticipated in the present invention. Additionally, it is anticipated that the combination of one rotation stop  132  is practiced with two rotation limit slots of different arc lengths, to allow a user to select multiple range limits on a single holder  40 . 
     In use, the present holder  40  is attached to the drive end boss  18  of the inserter handle  10 . In a first step A as shown in  FIG. 5A , the annulus axis  56  is aligned with the draw piston axis  21 . Once aligned, the annular opening  54  of the housing  42  is slid over the boss  18  in a second step B until the attachment mechanism  58  engages the complementary mating mechanism  23  on the boss  18 . In a third step C, the threaded interface  120  of the yoke  72  is then engaged with the piston threads  22  of the drive piston  20  by rotating the drive knob  32  of the drive train  30 . Sec  FIG. 5B . This results in the coupling mechanism  70  of the holder  40  being engage by and in mechanical communication with the drive assembly/linkage  30  of the inserter handle  10 . 
     Once the holder  40  is attached to the drive end boss  18  and engaged with the drive assembly  30 , the prosthesis component  12  is positioned on the front surface  44  of the housing  42 . In the embodiment illustrated, the prosthesis component  12  is a cup insert as is known in the field. To fully secure the prosthesis component  12  to the holder  40 , and in turn, the holder  40  to the boss  18 , the drive assembly lever  34  is pushed down and locked to draw the drive piston  20  into the boss  18  in a final step D. This actuates the coupling mechanism  70  of the holder  40  and causes the securing of the component  12  to the holder  40  and the holder  40  to the boss interface  16 , as described above. 
     After the inserter handle  10  with the holder  40  and prosthetic component  12  attached is used to properly position the prosthetic component  12 , in situ, in the patient&#39;s body, the drive assembly lever  34  is unlocked and released to free the handle  10  and holder  40  combination from the prosthetic component  12 . The inserter handle  10  and holder  40  are quickly free from each other by unthreading the draw piston  20  from the holder  40 . 
     An advantage of the present invention is that, once the proper relationship of the prosthetic component is achieved in the installation site, it is not necessary to hold the positional relationship of the inserter handle relative to the installation site during disengagement of the threaded interface of the mount end of the inserter handle from the prosthetic component. An advantage of the present invention is that it allows an existing inserter handle to be quickly disengageable from an attached prosthetic component, and requires little manipulation to accomplish that. An additionally advantage is that the present holder can provide an interface that can accommodate a variety of prosthetic component configurations for combination with a given inserter handle. 
     Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of modifications, changes, and substitutions is contemplated in the foregoing disclosure. While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of one or another preferred embodiments thereof. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the foregoing description be construed broadly and understood as being given by way of illustration and example only, the spirit and scope of the invention being limited only by the appended claims.

Technology Category: a