Patent Publication Number: US-8123816-B2

Title: Acetabular shell

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 11/810,829, filed on Jun. 6, 2007, now U.S. Pat. No. 7,682,399, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to orthopedics and, in particular, to an acetabular prosthetic implant. 
     Total hip replacement surgery typically entails the removal and replacement of the femoral head portion of the femur, as well as the resurfacing and replacement of the acetabulum. In both cases, prosthetic implants are utilized to replace the removed bone portions. Although these types of surgeries have become rather common place, surgeons are often faced with decisions during surgery relating to the particular prosthetic implants utilized, in addition to their respective orientation and positioning. For example, acetabular cup replacements may require a surgeon to first implant a shell portion and thereafter select different cup inserts and position them with respect to the shell portion. Several attempts at providing beneficial acetabular cup assemblies have been developed heretofore. Some examples of such acetabular cup assembly designs are disclosed in U.S. Pat. Nos. 6,475,243 (“the &#39;243 patent”) and 6,610,097 (“the &#39;097 patent”), and U.S. Patent Application Publication Nos. 2005/0288793 (“the &#39;793 application”) and 2006/0190089 (“the &#39;089 application”), the disclosures of which are hereby incorporated by reference herein. 
     The variety of conditions encountered when utilizing such implants has led to the use of various bearing materials and attachment methods placed at an optimum position and orientation, as determined by conditions encountered at the site of the implant. The choice of particular material for the bearing, as well as the size, positioning and orientation of the bearing member, is determined by the surgeon performing the procedure. Usually such choices are made on the basis of a pre-operative assessment of the needs of a particular patient. However, some times the choices are not apparent until the implant site is actually being prepared and the conditions encountered at the site can be evaluated during the implantation procedure itself. Accordingly, it would be advantageous to have available a greater range of interoperative choices, as well as pre-operative choices, so as to enable a surgeon to accommodate the needs of a particular patient as determined by either or both a pre-operative assessment and an evaluation of conditions encountered at a particular implant site, and to do so in a practical manner. 
     Especially in the case of revision surgical procedures wherein the pelvis has been severely compromised or deteriorated, it is known to use support structures to receive an acetabular prosthetic device. For example, in the &#39;793 application, the invention disclosed relates to optional modular adaptors which include wings, straps, or flanges to enhance the support of the acetabular prosthesis on the pelvis. Often times, devices including such extensions for connection with the pelvis, while often necessary, are difficult to insert through an incision and manipulate at the implantation site. Specifically, devices having multiple extensions extending in opposition or different directions often require a significant amount of unneeded or unwanted added manipulation on the part of a surgeon. 
     Therefore, there exists a need for an easily implantable acetabular prosthetic device including supports or extensions for connection with the pelvis or other surrounding bone. 
     BRIEF SUMMARY OF THE INVENTION 
     A first aspect of the present invention is an acetabular cup assembly for a prosthetic hip joint. In accordance with one embodiment of the present invention, the assembly includes an outer shell for attachment to the acetabulum, with the outer shell having an inner surface and at least one radially extending shell extension, a bearing insert, and an adaptor having an outer surface for engaging the inner surface of the outer shell, an inner surface for receiving the bearing insert portion, and at least one radially extending adaptor extension. 
     In accordance with certain other embodiments of the present invention, the at least one shell extension and at least one adaptor extension may each include at least one aperture, and such may also include a plurality of apertures. In other embodiments, at least one of the at least one shell extension and at least one adaptor extension are deformable at least in one direction, and a reduced cross-section may facilitate the deformation. The reduced cross-section may be formed by a groove. Both the at least one shell extension and the at least one adaptor extension are deformable. Preferably, the inner surface of the outer shell and the outer surface of the adaptor have complimentary tapered locking surfaces, and the adaptor may include a plurality of anti-rotation scallops for cooperation with complimentary structure on the outer shell. In other preferred embodiments, the at least one shell extension is shaped to cooperate with an illium, and the at least one adaptor extension is shaped to cooperate with an ischium. Finally, in certain embodiments, the adaptor includes a rim area, with the at least one adaptor extension extending from the rim area. 
     A second aspect of the present invention is a kit for resurfacing an acetabulum. In accordance with one embodiment of this second aspect, the kit includes at least one outer shell for attachment to the acetabulum, with the outer shell having an inner surface and at least one radially extending shell extension, at least one bearing insert, and a plurality of adaptors each having an outer surface for engaging the inner surface of the outer shell, an inner surface for receiving the bearing insert portion, and at least one radially extending adaptor extension. 
     In certain kit embodiments, the inner surface of the outer shell and the outer surfaces of the plurality of adaptors may have complimentary tapered locking surfaces, and the plurality of adaptors may each include a plurality of anti-rotation scallops for cooperation with a complimentary structure on the outer shell. The inner surfaces of the plurality of adaptors and an outer surface of the at least one bearing insert may have complimentary locking surfaces. In other embodiments, the at least one adaptor extension varies for each adaptor in the kit. 
     A third aspect of the present invention is a method of implanting an acetabular portion of a prosthetic hip joint. In accordance with one embodiment of this third aspect of the present invention, the method includes the step of preparing an acetabulum of a patient, providing an outer shell for attachment to the acetabulum, with the outer shell having at least one radially extending shell extension, providing a bearing insert, providing an adaptor having at least one radially extending adaptor extension, inserting the outer shell into the prepared acetabulum, connecting the at least one shell extension to the patient, inserting the adaptor into the outer shell, connecting the at least one adaptor extension to the patient, and inserting the bearing insert into the adaptor. 
     In certain embodiments of this third aspect method, the shell extension connecting step includes connecting the at least one shell extension to an illium of the patient. In other or the same embodiments, the adaptor extension connecting step includes connecting the at least one adaptor extension to an ischium of the patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the subject matter of the present invention and the various advantages thereof can be realized by reference to the following detailed description in which reference is made to the accompanying drawings in which: 
         FIG. 1  is perspective view of an acetabular cup replacement assembly according to a first embodiment of the present invention. 
         FIG. 2  is a top view of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 3  is an exploded view of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 4  is a perspective view of an outer shell portion of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 5  is another perspective view of the outer shell portion of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 6  is a top view of the outer shell portion of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 7  is a side perspective view of an adaptor portion of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 8  is a top view of the adaptor portion of the acetabular cup replacement assembly of  FIG. 1 . 
         FIG. 9  is a top view depicting the adaptor portion of  FIGS. 7 and 8  disposed in the shell portion of  FIGS. 4-6 . 
         FIG. 10  is a side view of an adaptor portion of an acetabular cup replacement assembly according to another embodiment of the present invention. 
         FIG. 11  is a top view of the adaptor portion of  FIG. 10 . 
         FIG. 12  is a perspective view of an adaptor portion of an acetabular cup replacement assembly according to yet another embodiment of the present invention. 
         FIG. 13  is a top view of the adaptor portion of  FIG. 12 . 
         FIG. 14  is a top view of an adaptor portion of an acetabular cup replacement assembly according to another embodiment of the present invention. 
         FIG. 15  is a side view of the adaptor portion of  FIG. 14 . 
         FIG. 16  is a top view of an adaptor portion of an acetabular cup replacement assembly according to another embodiment of the present invention. 
         FIG. 17  is a perspective view of an adaptor portion of an acetabular cup replacement assembly according to another embodiment of the present invention. 
         FIG. 18  is a top view of the adaptor portion of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, when referring to bones or other parts of the body, the term “proximal” means closer to the heart and the term “distal” means more distant from the heart. The term “inferior” means lower or bottom and the term “superior” means upper or top. The term “anterior” means towards the front part of the body or the face and the term “posterior” means towards the back of the body. The term “medial” means toward the midline of the body and the term “lateral” means away from the midline of the body. 
     Referring to the drawings, wherein like reference numerals refer to like elements, there is shown in  FIGS. 1-3 , an acetabular cup replacement assembly designated generally by reference numeral  10 . As shown in those figures, assembly  10  includes an outer shell portion  12 , an adaptor portion  14 , and an insert portion  16 . Adaptor  14  is preferably designed both to be received within outer shell  12  and to receive insert  16 . However, it is noted that shell  12  may also be capable of receiving insert  16  directly. Of course, this would require the use of a larger insert  16  than one which is to be received in adaptor  14 . Preferably, an insert  16  to be received directly into outer shell  12  would exhibit size and shape parameters similar to that of adaptor  14  designed to likewise be received in shell  12 . In all cases, shell  12  is preferably sized and shaped to be received within an already prepared acetabulum of a patient, and all other components of assembly  10  are to be sized and shaped according to the selected shell  12 . It is to be understood that preparation of the acetabulum of a patient is preferably done in accordance with well known and well developed surgical procedures often employed during a total hip replacement. Those of ordinary skill in the art would recognize such and also any procedures created subsequent to the present invention that could likewise be utilized. 
     The specific interconnection among the various components of assembly  10  will not be discussed in detail herein. Rather, it is to be understood that the interconnection among shell  12 , adaptor  14 , and insert  16  results from previously developed and/or used devices, such as taper connections among the various elements. For example, the &#39;243 patent, the &#39;097 patent, the &#39;793 application, and the &#39;089 application, which are all incorporated by reference herein in their entirety, teach various interconnections that may be employed by the present invention. It is to be understood that this list of incorporated references is by no means exhaustive, and also includes U.S. Patent Application Publication No. 2007/0106392 (“the &#39;392 application”) filed on Nov. 8, 2005, the disclosure of which is also hereby incorporated by reference herein, among others. In the embodiment depicted in  FIGS. 1-9 , adaptor  14  includes anti-rotation scallops  18  for cooperation with complimentary structure on shell  12  and insert  16  includes anti-rotation scallops  20  for cooperation with complimentary structure on adaptor  14 . Scallops  18  prevent rotation of adaptor  14  with respect to shell  12 , and scallops  20  prevent rotation of insert  16  with respect to adaptor  14 . However, it is noted that other structure may be employed, as set forth in the incorporated references or otherwise, and it is also to be understood that such anti-rotation elements are not required in the present invention. 
     As is best shown in  FIGS. 4-6 , outer shell  12  includes, among other elements, a semi-circular shell body  22  having an exterior surface  24  and an interior surface  26 . Preferably, exterior surface  24  is designed so as to be abutted against an already prepared acetabulum of a patient, while interior surface  26  is designed so as to receive either an appropriately sized adaptor  14  or an appropriately sized insert  16 . Shell body  22  may further include one or more shell body apertures  28  that extend from interior surface  26  to exterior surface  24  for receiving bone anchoring elements (not shown) such as screws or pins, and a rim  30  extending around the perimeter of interior surface  26 . Extending from rim  30  is a shell flange or shell extension  32 . Shell extension  32  includes a top surface  34 , a bone contacting bottom surface  36 , and one or more shell extension apertures that extend from top surface  34  to bottom surface  36 . These apertures  38  are preferably designed to receive bone anchoring elements, like that of body apertures  28 . Although shown extending from rim  30 , it is to be understood that shell extension  32  could extend from other portions of outer shell  12 , including, but not limited to, exterior and interior surfaces  24  and  26 . Moreover, although shown as being integral with rim  30 , shell extension  32  could be designed to be removably coupled with any portion of outer shell  12 . 
     In the particular design of outer shell  12  best shown in  FIGS. 4-6 , shell extension  32  is designed so as to cooperate and be anchored to the illium bone of a patient. The particular configuration shown has been created to match traditional patient anatomy and its shape is based on the anatomical study of a plethora of specimens. However, it is to be understood that variously sized and shaped shell extensions  32  may be employed in accordance with the present invention. For instance, shell extension  32  could be configured to cooperate and be anchored to another bone, such as the ischium of a patient. In addition, shell extension  32  may be designed so as to be deformable in at least one direction so as to allow a surgeon the freedom to match patient anatomy in situ. One manner in which this deformable structure may be achieved is more specifically taught in the &#39;793 application, and essentially involves providing shell extension  32  with a reduced cross-section, such as a groove, to facilitate the deformation. In such a case, the surgeon performing the surgery can simply tailor the shape of shell extension  32  to the particular shape, while outer shell is in the body or not. A tool may be necessary to effectuate the deformation. Finally, it is noted that other configurations, some of which are discussed below in relation to an adaptor extension, may similarly be employed with outer shell  12 . The particular configuration depends upon the surgeon preference and the particular patient anatomy. 
     As is best shown in  FIGS. 7 and 8 , adaptor  14  includes, among other elements, a semi-circular adapter body  40  having an exterior surface  42  and an interior surface  44 . Preferably, exterior surface  42  is designed so as to be placed adjacent to or abutted against interior surface  26  of outer shell  12 , while interior surface  44  is designed so as to receive an appropriately sized insert  16 . It is to be understood that depending upon the specific interconnection employed among the various components, all or only a portion of exterior surface  42  may actually contact interior surface  26 . Likewise, depending upon the interconnection configuration, interior surface  44  may contact only a portion or all of insert  16 . Unlike body  22  of outer shell  12 , body is preferably solid except for one centrally located adaptor body aperture  46  that is preferably designed to align with a similarly centrally located aperture  29  (best shown in  FIG. 6 ) formed in shell body  22 . This alignment allows for one relatively short anchoring element  31  (best shown in  FIG. 3 ) to pass through both adaptor  14  and outer shell  12 . This preferably adds to the locking of the adaptor to the shell. Adaptor body  40  also preferably includes a rim  48  extending around the perimeter of interior surface  44 . The above discussed scallops  18  are situated on rim  48  and extending from rim  48  is an adaptor flange or adaptor extension  50 . Adaptor extension  50  includes a top surface  52 , a bone contacting bottom surface  54 , and one or more adaptor extension apertures  56  that extend from top surface  52  to bottom surface  54 . These apertures  56  are preferably designed to receive bone anchoring elements. Although shown extending from rim  48 , it is to be understood that adaptor extension  50  could extend from other portions of adaptor  14 . Moreover, although shown as being integral with rim  30 , shell extension  50  could be designed to be removably coupled with any portion of adaptor  14 . 
     Like shell extension  32 , adaptor extension  50  is configured to cooperate with and be anchored to a bone, in this case, the ischium bone of a patient. Once again, the particular configuration shown has been created to match traditional patient anatomy and its shape is based on the anatomical study of a plethora of specimen, and it is to be understood that variously sized and shaped adaptor extensions  50  may be employed in accordance with the present invention. For instance, adaptor extension  50  could be configured to cooperate and be anchored to another bone, such as the illium of a patient. In addition, adaptor extension  50  may be designed so as to be deformable in at least one direction so as to allow a surgeon the freedom to match patient anatomy in situ, in a similar fashion as is discussed above in relation to shell extension  32 .  FIG. 9  depicts adaptor  14  disposed within outer shell  12 . 
       FIGS. 10-18  depict several different adaptors contemplated in accordance with the present invention. Although not exhaustive, these figures show adaptors which are substantially similar to the above-discussed adaptor  14 , except for the inclusion of different flange or extension in each case. The particular embodiment adaptor shown is accorded its own reference number, with similar elements to that of adaptor  14  being accorded similar reference numerals within a larger series of numbers. For example,  FIGS. 10 and 11  depict an adaptor  114  including a body  140  having an exterior surface  142 , an interior surface  144 , a centrally located adaptor body aperture  146 , and a rim  148 . Adaptor  114  further includes an adaptor extension  150  having a top surface  152  and a bottom surface  154 . Although not shown, extension  150  may include one or more apertures for receiving a bone fixation element, similar to that discussed above. Adaptor  114  is substantially similar to that of adaptor  14 , except for the fact that extension  150  is of an inferior hook design. Such may useful in certain hip procedures, depending upon anatomical conditions or the preference of a surgeon. 
     Like  FIGS. 10 and 11 , the remaining figures show different embodiment adaptors having similar elements, but different flanges or extensions.  FIGS. 12 and 13  depict an adaptor  214  having an adaptor extension  250  similar in design to shell extension  32 .  FIGS. 14 and 15  depict an adaptor  314  having an adaptor extension  350  which essentially extends around the entire perimeter of rim  348 .  FIG. 16  depicts a similar construction adaptor  414  having an adaptor extension  450  which only extends around a portion of the perimeter of rim  448 . Finally,  FIGS. 17 and 18  depict an adaptor  514  which employs both an adaptor extension  550  similar in nature to adaptor extension  50 , and an adaptor extension  551  similar in nature to adaptor extension  250 . In this latter design, assembly  10  would ultimately include three extensions (including shell extension  32 ). Of course, any number of flanges or extension may be included on either the outer shell or adaptor of any given system. 
     It is to be understood that any of the variations discussed herein similarly apply to all embodiments disclosed herein. With regard to the alternate embodiments depicted in  FIGS. 10-18 , it is to be understood that any particular adaptor may be selected by a surgeon depending upon his or her preferences or the particular anatomical landscape of the patient. In this regard, it is contemplated to provide a kit in accordance with the present invention. A kit of this type would preferably allow a surgeon to make a decision as to the particular components to be utilized either before or during a surgical procedure. Among other elements, the kit would preferably include at least one outer shell  12 , at least one bearing insert  16 , and any number of the above-discussed adaptors  14 ,  114 ,  214 ,  314 ,  414 , and  514 . In addition, the kit may include various sizes of each component and could include different shells  12  and inserts  16 , in accordance with the variations discussed herein or in the above-incorporated patents and patent applications. For instance, a kit in accordance with the present invention may include a series of increasing size shells  12 , multiple different types of inserts in similar varying sizes, and varying size adaptors with different extensions, like in adaptors  14 ,  114 ,  214 ,  314 ,  414 , and  514 . The kit may include one or more tools, fasteners or the like, and may be tailored to the particular patient, based upon preoperative research into the patient&#39;s anatomy and needs. 
     In a typical surgical operation involving the replacement of an acetabular portion of a patient, the surgeon would first take the necessary steps to prepare the acetabulum. As is mentioned above, this may be done in accordance with any well-known or hereafter developed process, and may include the removal of a certain amount of bone or other body tissue. Once the acetabulum has been prepared, the surgeon would then insert outer shell  12  through an incision in the patient and into the prepared acetabulum. Exterior surface  24  of shell  12  would ultimately abut the prepared acetabular surface, and one or more fixation elements may be inserted through apertures  28  and into the acetabular bone. In addition, shell extension  32  would be contacted with a bone surface in the general area of the acetabulum. Once in the correct position, one or more fixation elements may be inserted through apertures  38  and into this bone. All of this may be accomplished through one or more incisions and with or without the use of navigational components. 
     With outer shell  12  in position, the surgeon would then select an adaptor from a group of adaptors including without limitation adaptors  14 ,  114 ,  214 ,  314 ,  414 , and  514 . It is noted that the particular adaptor selected should be sized and shaped to properly engage shell  12 , and should include a flange or extension suitable for engagement with a nearby bone. For explanation purposes, we will assume the surgeon selects adaptor  14 . Adaptor  14  should then be inserted through the aforementioned incision or one of the aforementioned incisions, and into shell  12 . Depending upon the desired orientation of the adaptor extension, the surgeon may need to turn adaptor  14  within shell  12  in order to achieve the correct orientation of the extension. Exterior surface  42  of adaptor  14  preferably engages at least a portion of interior surface  26  of shell  12 , and a fixation element may be inserted through apertures  46  and  29 . This preferably aids in the mechanical interconnection between shell  12  and adaptor  14 . In addition, adaptor extension  50  would be contacted with a bone surface in the general area of the acetabulum. It is noted that this bone may vary depending upon the particular flange or extension employed by the selected adaptor. Once in the correct position, one or more fixation elements may be inserted through apertures  56  and this bone. 
     Finally, the surgeon would select a suitable insert and similarly insert such into interior surface  44  of adapter  14 . Once again, this may involve engaging insert  16  with adapter  14 , depending upon the particular interconnection utilized. It is to be understood that some of the above-noted variations in relation to the particular components of assembly  10  may vary the particular method steps required in a surgical procedure. In addition, although not discussed with particularity herein, the other steps involved with a standard hip replacement procedure or the like are to be performed in accordance with the surgeon&#39;s mode of operation. Those of ordinary skill in the art would readily recognize what these steps may entail. The fact that each of outer shell  12  and adaptor  14  includes at least one flange or extension, as opposed to one or the other including all flanges or extensions, allows for the easier manipulation and implantation of assembly  10 . In previous assemblies, one of an outer shell or an adaptor would include multiple opposed flanges or extensions. This would make it difficult to position the flanges or extensions around soft tissue and directly against bone. In accordance with the present invention, the inclusion of one flange or extension on each of outer shell  12  and adaptor  14  allows a surgeon to more easily achieve this positioning, with minimal repositioning or ancillary movement of soft tissue or the like. Thus, the present invention provides for an easier positioned and implanted assembly  10 . 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.