Abstract:
Disclosed is an acetabular positioning and insertion instrument. Additionally, a method of positioning an acetabular prosthesis with an insertion instrument is disclosed. The positioning instrument can include engaging members to contact an acetabular prosthesis and holding it relative to a portion of the instrument for both rotational and positioning of the prosthesis.

Description:
FIELD 
       [0001]    The subject disclosure relates to systems and methods for positioning a prosthesis in a subject, and particularly relates to an instrument and methods for engaging and inserting an acetabular prosthesis in a subject. 
       BACKGROUND 
       [0002]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0003]    In performing a procedure on a patient, a prosthesis can be used to replace or augment a natural anatomical feature. For example, due to age, injury, disease, or other causes, a portion of the anatomy may need to be replaced or resurfaced. Examples include replacing an acetabulum on a patient either in conjunction with or separate from replacing or resurfacing a femoral head. An acetabular prosthesis is generally positioned within a prepared acetabulum. 
         [0004]    Positioning an acetabular prosthesis within a prepared acetabulum can include various dexterous movements of the prosthesis because the acetabular prosthesis is generally positioned within the acetabulum in a selected alignment and position. The alignment of the acetabular prosthesis is generally selected to be relative to the natural anatomy where a central axis of the acetabular prosthesis must be aligned or is selected to be aligned with a portion of the natural anatomy. In positioning the acetabular prosthesis in the selected position, both position and axial alignment can be selected. 
         [0005]    Along with position and axial alignment, the acetabular prosthesis also needs to be engaged into the acetabulum with a selected force to ensure proper seating and positioning of the acetabular prosthesis. Thus, the acetabular prosthesis is generally required to be held in the selected position and alignment during an impaction. Accordingly, positioning the acetabular prosthesis generally requires dexterity on the part of the user, such as a surgeon, to position the acetabular prosthesis appropriately in a patient&#39;s anatomy. 
       SUMMARY 
       [0006]    An acetabular prosthesis can be positioned in an anatomy, such as a human anatomy, to replace or repair a natural acetabulum. The natural acetabulum may need to be replaced due to injury or disease and can be prepared to receive an acetabular prosthesis according to generally understood methods. For example, the acetabulum can be reamed with a selected reamer. A prosthetic acetabulum can then be implanted into the prepared acetabulum. 
         [0007]    The prosthetic acetabulum can be engaged near an apical hole or region of the acetabular prosthesis to be held for positioning into the prepared acetabulum. The acetabular prosthesis can be held with an instrument that includes moveable or expanding jaws or fingers to engage the acetabular prosthesis. The moveable fingers can be expanded to engage the apical region of the acetabular prosthesis and then can be disengaged from the acetabular prosthesis to allow for removal of the instrument after implantation of the acetabular prosthesis. The fingers can be engaged and disengaged by biasing the fingers outwardly towards the acetabular prosthesis and removing the biasing force to allow them to collapse to disengage from the acetabular prosthesis. An instrument that holds the acetabular prosthesis can also be impacted to position and fix the acetabular prosthesis into the prepared acetabulum. 
         [0008]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0009]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0010]      FIG. 1  is a first perspective view on an acetabular positioning instrument; 
           [0011]      FIG. 2  is a second perspective view of the acetabular insertion instrument; 
           [0012]      FIG. 3A  is an elevational view of the acetabular insertion instrument; 
           [0013]      FIG. 3B  is a detail elevational view of an end the acetabular insertion instrument of  FIG. 3A ; 
           [0014]      FIG. 4A  is a third perspective view of the acetabular insertion instrument engaging an acetabular prosthesis; 
           [0015]      FIG. 4B  is a cross-sectional detail view of the acetabular insertion instrument engaging an acetabular prosthesis of  FIG. 4A ; and 
           [0016]      FIG. 5  is an environmental view of an acetabular insertion instrument positioning an acetabular prosthesis into a pelvis. 
       
    
    
       [0017]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0018]    With reference to  FIGS. 1 and 2 , an acetabular inserter handle assembly  20  is illustrated. The inserter handle assembly  20 , also referred to as an acetabular inserter handle or inserter handle, can include a first impaction or distal end  22  and a second or proximal prosthesis engagement end  24 . Between the two ends  22 ,  24 , is a handle or grasping portion  26 , a manipulation or biasing region  28 , and an extension or holding tubular region  30 . 
         [0019]    The handle region  26  can include a graspable portion  40  to be held by a user or a user&#39;s hand during impaction and manipulation of an acetabular prosthesis ( FIG. 4  of  130 ), as discussed further herein. The inserter handle  20  can be used to engage an acetabular prosthesis and the user can engage or hold the handle  40  to manipulate the handle assembly  20  with one hand. A second hand of the user or an assistant&#39;s hand can be used to impact an impaction portion  42  such as with a mallet or hammer  44 . The handle or grasping portion  40  can include ridges or a knurled surface or other appropriate friction or grasping region to allow for a user to securely hold the handle assembly  20  during the manipulation of an acetabular prosthesis. The mallet  44  engaging or impacting the impaction end  42  can drive or provide a force along a longitudinal axis  46  of the inserter assembly  20 . The longitudinal axis  46  of the inserter assembly  20  can generally define an axis or a line along which a force is transferred from the impact end  42  to the engaging end  24 , as discussed further herein. 
         [0020]    The biasing region  28  can include a moveable member  50 , that can also be referred to as a biasing lever or plate that can have at least two portions or ears extending from the biasing region  28 . The moveable member  50  can extend from a housing or chassis portion  52  through openings or windows  54  formed in one or more regions of the chassis  52 . The windows  54  can be defined by a wall or walls  56  of the chassis member  52 . 
         [0021]    Within the chassis portion  52 , a biasing spring or member  60  can be positioned between a distal wall or first wall  62  and the moveable member  50 . The moveable member  50  can define a surface  64 . The biasing member  60  can include a compression or spiral spring that is positioned between the two surfaces  62 ,  64  to bias the moveable member  50  generally in the direction of the proximal end  24  in the direction of arrow A. As discussed further herein, the biasing of the moveable member  50  can assist in holding and positioning an acetabular prosthesis relative to the inserter handle  20 . The biasing member  60  can be any appropriate biasing member such as a resilient material, including a natural or artificial rubber, or other appropriate material or device that provides a biasing force onto the surface  64  in the direction of arrow A to hold a prosthesis or selected member relative to the inserter handle  20 . 
         [0022]    The moveable member  50  can be moved by a user against the biasing force of the compression spring member  60  such that the member  50  moves towards the distal end  22  generally in the direction of arrow B, as illustrated in  FIG. 2 . With continuing reference to  FIG. 2 , and additional reference to  FIGS. 3A and 3B , the member  50  is connected to a rod or moveable member  70  that passes through a cannula or bore of a tube  72  towards the proximal end  24  of the handle assembly  20 . As illustrated in  FIGS. 3A and 3B , the tube  72  is shown in phantom to illustrate the length of the rod  70 . The rod  70  can extend from the member  50  towards the proximal end  24  and can have a proximal end  74 . The proximal end  74  can be positioned between two fingers or projections  76  and  78  to bias the two fingers  76 ,  78  apart, which can also be away from a central axis  80  of the rod  70 . Thus, the rod  70  can be an adjusting member to bias the fingers  76 ,  78  away from one another in an expanded position. 
         [0023]    The rod  70  can include a ramp or slanted surface that includes tapering outer edges  82  and  84  that tapers at an angle  88  relative to the central axis  80 . Accordingly, when the rod  70  is biased in the direction of arrow A, that is when the member  50  is biased in the direction of Arrow A by the biasing member  60 , the fingers  76 ,  78  are biased away from the central axis  80 . When the rod  70  is moved in the direction of arrow B, when the member  50  is moved against or forced against the compression member  60 , the biasing force is no longer present between fingers  76 ,  78  and the fingers can move toward the central axis  80 . 
         [0024]    The fingers  76 ,  78 , can therefore move in two directions. In the first direction when they are biased and in a biased position, the fingers  76 ,  78  are in an expanded position such that an outer dimension of the fingers or at least a portion thereof, defines a maximum or large outer dimension. When the rod  70  is moved out of the biasing position, such as when the member  50  is moved in the direction of arrow B, the fingers  76 ,  78  are allowed to collapse or move towards one another and the central axis  80 . In the collapsed position, the fingers  76 ,  78  define an outer dimension that is less than the expanded dimension. In a collapsed position, the fingers  76 ,  78  may disengage a member, as discussed further herein. 
         [0025]    The fingers  76 ,  78  can each include an axle or pivoting region or member  92 ,  94  that allows the respective fingers  76 ,  78  to rotate towards the central axis  80  or away from the central axis  80 . During the rotation, the proximal ends  76   a ,  78   a , of the respective fingers,  76 ,  78  can move away from or towards the central axis  80 . The proximal ends  76   a ,  78   a  can further include respective projections  76   b ,  78   b  or portions that extend from an outer surface  76   c ,  78   c  to allow for a positive engagement with a prosthesis, such as an acetabular prosthesis, as discussed further herein. With particular reference to  FIG. 2 , the cylinder or tube  72  can include an outer wall  100  through which the axles or rotating portions  92 ,  94  can extend to provide a fixed axis of rotation for each of the respective fingers  76 ,  78 . Openings  102  in the outer wall  100  can also allow portions of the fingers to extend to further contact portions of the wall  100 . 
         [0026]    The inserter handle  20  can be used to engage an acetabular prosthesis  130 , as illustrated in  FIG. 4 . The acetabular prosthesis can include a distal or upper rim  132  that defines an opening to an interior  134  of the acetabular prosthesis  130 . The interior of the acetabular prosthesis  134  can include an apical opening or passage  140 . The apical opening  140  can be an open bore or a blind bore into the acetabular prosthesis  130 . According to various embodiments, the acetabular prosthesis  130  can include an apical bore through which a fixation screw or implantation handle, such as the handle assembly  20 , can engage the acetabular prosthesis  130 . It is understood, however, that the insertion handle  20  need not pass through the acetabular prosthesis  130 , therefore a through bore is not necessary in the acetabular prosthesis  130 . Nevertheless, the acetabular prosthesis  130  can define an undercut or depression  142  that can be engaged by the projections  76   b ,  78   b  and/or ends  76   a ,  78   a  of the fingers  76 ,  78 . 
         [0027]    As illustrated in  FIG. 4 , the proximal projections  76   b ,  78   b  of the fingers  76 ,  78  project into the undercut  142  of the acetabular prosthesis  130  when the rod  70  is biased in the direction of arrow A and the proximal end  74  is positioned between the fingers  76 ,  78  to bias them away from the central axis  80  and into the undercut  142 . The acetabular prosthesis  130  can further include a non-circular or keyed opening  144 , such as a square opening near the apical opening  140 , to engage a square or proximal edge  146  as illustrated in  FIG. 1 . The keyed or non-circular proximal edge  146  engaged in the opening  144  can fix rotation of the acetabular prosthesis  130  relative to the proximal end  24  of the inserter handle  20 . The acetabular prosthesis  130  can, therefore, be held rotationally and axially relative to at least the proximal end  24  of the inserter handle. 
         [0028]    As illustrated in  FIG. 4 , the rod  70  is biased in the direction of arrow A, which can also be referred to as the bias direction, by the biasing member  60 , as illustrated in  FIG. 3A . When the acetabular prosthesis  130  is connected to the handle assembly  20 , as illustrated in  FIG. 4 , the handle assembly  20  can be used to implant the acetabular prosthesis  130  into a prepared acetabulum  160  of a selected pelvis  162 , as illustrated in  FIG. 5 . The acetabular prosthesis  130  can be held with the inserter handle  20  due to engagement of the fingers  76 ,  78 , in the biased position of the rod  70 , with the acetabular prosthesis  130 . 
         [0029]    The inserter assembly  20  can then be disengaged from the acetabular prosthesis after positioning it relative to the prepared acetabulum  140  by moving the member  50  against the biasing member  60  to move the rod  70  out of engagement and the biased position with the fingers  76 ,  78 . Once the rod  70  is moved out of engagement with the fingers  76 ,  78 , the fingers  76 ,  78  can move towards the central axis  80  to disengage the undercut  142  of the acetabular prosthesis  130 . The fingers  76 ,  78  move to the unbiased position to disengage from the prosthesis  130 . Once disengaged, the inserter handle  20  can be removed from the acetabular prosthesis  130  to allow for a completion of a procedure. Completing the procedure can include reduction of a femoral head of a femur or a femoral head of a prosthesis, positioning of a bearing within the acetabular prosthesis  130 , and/or closing the patient. 
         [0030]    Once the handle assembly  20  is disengaged from the acetabular prosthesis  130 , it can be reengaged with the acetabular prosthesis  130  by moving the rod  70  and the member  50  against the biasing member  60  to allow the fingers  76 ,  78  to move towards the central axis  80 . When the fingers  76 ,  78  move towards the central axis  80 , the fingers  76 ,  78 , including the projections  76   b ,  78   b  can be moved into the central or apical bore  140 , including the undercut  142 . The member  50  can then be disengaged to allow the member  50  and the rod  70  to be biased in the direction of arrow A such that the rod  70  biases the fingers  76 ,  78  away from the central axis  80 . When biased, the projections  76   b ,  78   b  move into the undercut  142  to engage the acetabular prosthesis  130 . Accordingly, after the handle assembly  20  is used to position the acetabular prosthesis  130  into the prepared acetabulum  160  of the pelvis  162 , the inserter assembly  20  can also be used to disengage the positioned acetabular prosthesis  130  from the prepared acetabulum  160 . The fingers  76 ,  78  include projections  76   b ,  78   b  to allow for the positioning and removal of the inserter assembly  20  in a substantially axial direction only without requiring rotation of the inserter assembly  20  to engage and disengage the acetabular prosthesis  130 . Accordingly, the inserter assembly  20  can be used to efficiently engage the acetabular prosthesis  130  to position the acetabular prosthesis  130  and for removal of the acetabular prosthesis  130 . 
         [0031]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.