Abstract:
An introduction instrument for inserting a liner into an acetabular shell is disclosed. The instrument includes a suction device which may be selectively released once the liner is appropriately situated in the acetabular shell. Such selective release prevents disruption of the positioning of the liner and/or the acetabular shell.

Description:
BACKGROUND 
       [0001]    1. Field of the Disclosure 
         [0002]    This disclosure relates to an instrument used for orthopaedic surgery, and more particularly to an introduction instrument for inserting a liner into an acetabular shell. 
         [0003]    2. Description of the Related Art 
         [0004]    Acetabular cups may include a metallic acetabular shell and a liner. The liner may be formed of various materials such as metal, polyethylene, and ceramic. During an exemplary orthopaedic surgical procedure, the acetabular shell is implanted into an acetabulum of a patient. Once the shell is positioned, the liner is secured to the acetabular shell to provide an articulating surface for articulating with a natural femoral head or a femoral head prosthesis. Sufficient fixation and correct placement of the liner relative to the acetabular shell facilitates proper functioning and longevity of the acetabular cup. 
       SUMMARY 
       [0005]    The present disclosure provides an introduction instrument for inserting the liner into the acetabular shell. The instrument includes a suction device which may be selectively released once the liner is appropriately situated in the acetabular shell. Such selective release prevents disruption of the positioning of the liner and/or the acetabular shell. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The above-mentioned and other features of this disclosure will become more apparent and the disclosure itself will be better understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein: 
           [0007]      FIG. 1  is a perspective view of an introduction instrument according to the present disclosure; 
           [0008]      FIG. 2  is a partial cross-sectional perspective view of the introduction instrument of  FIG. 1 ; 
           [0009]      FIG. 3  is a fragmentary cross-sectional view of a portion of the introduction instrument of  FIG. 2 ; 
           [0010]      FIG. 4  is a perspective view of a suction cup of the introduction instrument of  FIG. 1 ; and 
           [0011]      FIG. 5  is a fragmentary cross-sectional view of a portion of the introduction instrument of  FIG. 2 . 
       
    
    
       [0012]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the disclosure and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner. 
       DETAILED DESCRIPTION 
       [0013]    Referring to  FIGS. 1 and 2 , introduction instrument  20  is shown and generally includes outer housing or frame  22 , inner shaft or plunger  24 , and suction cup  26 . Introduction instrument  20  may be used to insert liner component  28  into an acetabular shell (not shown) of an acetabular cup assembly. Outer housing  22  includes outer housing distal end  30  and outer housing proximal end  32 . Outer housing  22  may include knurled surface  46  to enhance gripping friction of outer housing  22 . Inner shaft  24  includes inner shaft distal end  34  and inner shaft proximal end  36 . Inner shaft  24  may include proximal end face  44  for facilitating use of inner shaft  24  via a thumb, for example. Suction cup  26  includes suction cup cannula  38  extending throughout suction cup  26  from suction cup distal end  48  to suction cup proximal end  50 . Suction cup  26  includes suction cup face  62 . 
         [0014]    Referring now to  FIGS. 2-5 , suction cup  26  includes suction cup cannula first section  56 , second section  58 , and third section  60 . The interface between first section  56  and second section  58  defines suction cup cannula first shoulder  40 . The interface between second section  58  and third section  60  defines suction cup cannula second shoulder  42 . Suction cup cannula first section  56  defines a first diameter D 1 , suction cup cannula second section  58  defines a second diameter D 2 , and suction cup cannula third section  60  defines a third diameter D 3 . In an exemplary embodiment, first diameter D 1  is larger than second diameter D 2  and second diameter D 2  is larger than third diameter D 3 . In one embodiment, second diameter D 2  is between approximately 0.1 and 0.2 inches. In an exemplary embodiment, second diameter D 2  is approximately 0.125 inches. In one embodiment, first diameter D 1  is between approximately 0.2 and 0.3 inches. In an exemplary embodiment, first diameter D 1  is approximately 0.250 inches. In one embodiment, suction cup cannula first section  56  may taper towards suction cup distal end  48  such that first diameter D 1  increases to between approximately 0.3 and 0.4 inches at proximal end  50  (while first diameter D 1  near suction cup distal end  48  remains between approximately 0.2 and 0.3 inches), and, in an exemplary embodiment, first diameter D 1  increases to approximately 0.330 inches at suction cup proximal end  50  (while first diameter D 1  near suction cup distal end  48  remains approximately 0.250 inches). The taper connection between suction cup  26  and outer housing  22  facilitates connection and assembly therebetween. In one embodiment, third diameter D 3  is between approximately 0.05 and 0.10 inches. In an exemplary embodiment, third diameter D 3  is approximately 0.062 inches. 
         [0015]    Referring still to  FIGS. 2 and 3 , inner shaft distal end  34  defines a fourth diameter D 4  between approximately 0.1 and 0.2 inches. In an exemplary embodiment, fourth diameter D 4  is approximately 0.170 inches. In an exemplary embodiment, inner shaft  24  is substantially cylindrical at distal end  34 . Outer housing distal end  30  defines a fifth diameter D 5  between approximately 0.250 and 0.3 inches. In an exemplary embodiment, fifth diameter D 5  is approximately 0.280 inches. Outer housing  22  may be substantially cylindrical at distal end  30  or outer housing  22  may include a slight taper or barb feature towards distal end  30  to facilitate connection and assembly while resisting unintended disengagement between outer housing  22  and suction cup  26 , as described below. In the tapered configuration, fifth diameter D 5  increases to between approximately 0.35 and 0.4 inches proximate suction cup proximal end  50  when assembled, and, in an exemplary embodiment, fifth diameter D 5  increases to approximately 0.360 inches proximate suction cup proximal end  50  when assembled. 
         [0016]    To assemble introduction instrument  20  and referring now to  FIG. 2 , a user, e.g., a surgical technician, nurse, or surgeon, inserts inner shaft  24  into outer housing  22 . Upon engagement of inner shaft exterior threads  52  with outer housing interior threads  54 , the user rotates inner shaft  24  relative to outer housing  22  to threadingly engage each other. Once sufficient rotation is imparted to inner shaft  24  relative to outer housing  22 , inner shaft exterior threads  52  move distally beyond outer housing interior threads  54  and become disengaged therefrom. At this point, outer housing interior threads  54  provide a barrier or stop to prevent unintended disengagement of inner shaft  24  from outer housing  22  and capture inner shaft  24  therein. Inner shaft  24  is allowed axial movement within outer housing  22  yet captured therein. 
         [0017]    Suction cup  26  is assembled to outer housing  22  via friction-fit engagement between suction cup cannula first section  56  and outer housing distal end  30 . As described above, outer housing distal end  30  includes fifth diameter D 5  which is slightly larger than first diameter D 1  of suction cup cannula first section  56 , thereby slightly deforming suction cup cannula first section  56  upon introduction of outer housing  22  into suction cup  26  and enhancing the friction-fit engagement therebetween. In an exemplary embodiment, first diameter D 5  is greater than first diameter D 1  by approximately 0.03 inches to 0.04 inches. In one embodiment, outer housing distal end  30  includes a tapered section or barb feature to further enhance the engagement between outer housing  22  and suction cup  26 . Suction cup  26  is pushed onto outer housing  22  until suction cup cannula first shoulder  40  abuts outer housing distal end surface  31 . Inner shaft  24  is then distally pushed such that inner shaft distal end  34  engages suction cup cannula second section  58 . As described above, inner shaft distal end  34  includes fourth diameter D 4  which is slightly larger than second diameter D 2  of suction cup cannula second section  58 , thereby slightly deforming suction cup cannula second section  58  upon introduction of inner shaft  24  into suction cup  26  and enhancing the friction-fit engagement therebetween. In an exemplary embodiment, fourth diameter D 4  is greater than second diameter D 2  by approximately 0.04 inches to 0.05 inches. Inner shaft  24  is pushed into suction cup  26  until inner shaft distal end surface  35  abuts suction cup cannula second shoulder  42 , thereby defining a first position of inner shaft  24  relative to outer housing  22  and suction cup  26 . Instrument  20  is then ready to be assembled with liner  28 . 
         [0018]    In operation, the user releasably attaches liner  28  to introduction instrument  20  by generally aligning suction cup  26  on an articulating surface of liner  28  and applying force in a direction generally along arrow A to force suction cup face  62  against liner  28  and thereby create a vacuum seal between introduction instrument  20  and liner  28 . The user proceeds to implant liner  28  into a shell (not shown) of an acetabular cup assembly. Upon final seating of liner  28  in the shell, the user grasps outer housing  22  near knurled surface  46 , for example, to statically hold outer housing  22  and proximally pulls inner shaft  24  relative to outer housing  22  to a position as shown in  FIG. 5 . Such movement of inner shaft  24  corresponding to a second position ( FIG. 5 ) of inner shaft  24  relative to outer housing  22  and suction cup  26  releases the seal created between suction cup  26  and liner  28 , thereby allowing introduction instrument  20  to release liner  28  therefrom without disturbing the seating relationship previously established with the shell. 
         [0019]    While this disclosure has been described as having exemplary designs, the present disclosure 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 disclosure 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 disclosure pertains and which fall within the limits of the appended claims.