Abstract:
An orthopedic implant structure is provided for joining and retaining components of a multi-part orthopedic device. The orthopedic implant joining and retaining structure may be embodied in two or more components of the multi-part orthopedic device. In one form, the multi-part orthopedic implant structure is a resilient snap structure such as a resilient flange in one part and a channel structure formed in another part of an orthopedic implant. A channel of the channel structure may have a cavity formed at a rear of the channel that accepts a configured lip formed on an end of the resilient flange. According to another embodiment, the retaining structure includes resilient snap flanges formed on an interconnection component of the multi-part orthopedic implant. A corresponding bore in another part of the multi-part orthopedic implant receives the interconnection component.

Description:
RELATED APPLICATIONS 
     This patent application claims the benefit of and/or priority to U.S. Provisional Patent Application No. 60/775,103 filed Feb. 21, 2006, entitled “Retaining Structure For Multi-Part Orthopedic Devices” the entire contents of which is specifically incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to orthopedic devices and components and, more particularly, to a structure for joining and retaining parts of multi-part orthopedic devices. 
     BACKGROUND OF THE INVENTION 
     Orthopedic treatment for the correction of skeletal problems due to trauma, injury, disease, deformity or the like can include orthopedic surgery for implanting one or more orthopedic devices. Orthopedic surgery is now commonly used to implant artificial joints, mend bones and correct spinal problems. The manufacture of orthopedic implants such as joint replacement devices and spinal devices comprises a large sector of the orthopedic industry. 
     Because of the configuration of some orthopedic implants, various types of orthopedic implants need to be assembled before use. Sometimes assembly is accomplished before implantation and sometimes assembly is accomplished during implantation. In either case, the parts or components of the orthopedic implant need to be joined in a reliable, accurate and dependable manner that allows the assembly and retention of the components. Thus, a structure is necessary to allow the components of the orthopedic implant to be joined and retained in a reliable, accurate and dependable manner. 
     In view of the above, it is desirable to provide a structure to join and retain components or parts of an orthopedic implant in a reliable, accurate and dependable manner. It is thus an object of the present invention to provide a structure and/or manner to join one part of an orthopedic implant with another part of the orthopedic implant in order to hold the parts together during use. 
     SUMMARY OF THE INVENTION 
     An orthopedic implant structure is provided for joining and retaining components of a multi-part orthopedic device. The orthopedic implant joining and retaining structure may be embodied in two or more components of the multi-part orthopedic device. 
     In one form, the multi-part orthopedic implant joining and retaining structure is a resilient snap structure. The present structure provides a positive, reliable, accurate and dependable joining and retention mechanism that is fabricated from a bio-compatible material. 
     According to one embodiment, the retaining structure includes a partially open channel formed in one portion of one part of an orthopedic implant and a resilient flange formed in one portion of another part of the orthopedic implant. The channel has a cavity formed at a rear of the channel. A configured lip is formed on an end of the resilient flange. The resilient flange bends during insertion into the channel due to the configured lip and dimensions of the partially open channel. Once the lip of the flange reaches the cavity of the channel, the resiliency of the flange causes the flange to bend or snap into the cavity. Reverse motion of parts is inhibited by co-action of the lip and a front edge of the cavity. 
     Depending on the length of the cavity, the retaining structure may allow limited movement of one part relative to another part. In this manner, the orthopedic device may be limitedly dynamic. 
     According to another embodiment, the retaining structure includes resilient snap flanges formed on an interconnection component of the multi-part orthopedic implant. Corresponding recesses in another part of the multi-part orthopedic implant receives the interconnection component. Dimensioned channels terminating in an open area formed in two (or more) pieces of an orthopedic implant causes the deformation of the snap flanges of the interconnection component during connection that thereafter resiliently return to their original state upon reaching the open area. 
     Other snap configurations and orthopedic implants and/or devices are contemplated in accordance with the present principles. In one form, the resilient snap structure includes a resilient head structure of a bone screw that deforms upon insertion into a configured head structure of a spine fixation construct. In yet another form, the resilient snap structure includes configured, pivoting cams of a head structure of a spine fixation construct that snap into a configured connection plate. The connection plate is configured with a rim and trough that provide snap connection by the pivoting cams. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the present invention will become more apparent to one skilled in the art upon also reading the following description of embodiments with reference to the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a one level (1-L), two piece spine plate utilizing an embodiment of a retaining structure in accordance with the present principles; 
         FIG. 2  is a top perspective view of the one segment of the one level, two piece spine plate of  FIG. 1 ; 
         FIG. 3  is a bottom perspective view of the spine plate segment of  FIG. 2 ; 
         FIG. 4A  is an enlarged sectional view of the retaining structure illustrating the manner in which the retaining structure joins; 
         FIG. 4B  is an enlarged sectional view of the retaining structure after joining; 
         FIG. 5  is a perspective view of a two level (2-L), three piece spine plate utilizing an embodiment of a retaining structure in accordance with the present principles; 
         FIG. 6  is a top perspective view of a middle segment of the two level, three piece spine plate of  FIG. 5 ; 
         FIG. 7  is a bottom perspective view of the middle segment of  FIG. 6 ; 
         FIG. 8  is bottom plan view of the two level, three piece spine plate of  FIG. 5 ; 
         FIG. 9  is an exploded perspective view of a two-piece vertebral interbody device utilizing an embodiment of a retaining structure in accordance with the present principles; 
         FIG. 10  is an enlarged, perspective view of a portion of the two-piece vertebral interbody device illustrating anti-rotation features thereof; 
         FIG. 11  is an enlarged perspective view of a two-sided retention post utilized to join the two pieces of the vertebral interbody device of  FIG. 9 ; 
         FIG. 12  is a top view of the two-piece vertebral interbody device of  FIG. 9 , assembled; 
         FIG. 13  is a sectional view of the two-piece vertebral interbody device taken along line  13 - 13  of  FIG. 12 ; and 
         FIG. 14  is an enlarged sectional view of a portion of the two-piece vertebral interbody device taken along circle  14 - 14  of  FIG. 13 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the principles of the present invention. The exemplifications set out herein illustrate several embodiments of the invention, but the exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-8  depict various views of an orthopedic implant or device utilizing an embodiment of the present invention and particularly utilizing a joining and retaining structure. Referring to  FIG. 1  there is depicted an orthopedic implant generally designated  10  that is particularly a one level (1-L), two piece spine plate. The spine plate  10  is representative of the various types of spine plates that may use the present invention. 
     The spine plate  10  is preferably, but not necessarily, made from a suitable, biocompatible material such as titanium. The spine plate  10  is formed of identical first and second segments, parts, components or halves  12   a  and  12   b  one of which is rotated 180° relative to the other part, then joined with the other half. As such, the plate segment  12   b  is identical to plate segment  12   a  and thus the same parts of plate segment  12   b  are labeled with the same number but provided with the letter designation “b.” It should be appreciated that the present invention is not dependent upon such symmetry and thus can be used on non-symmetrical segments of spine plates. 
     Plate segment  12   a  has two screw bores  16   a  and  18   a  with a cover plate bore  20   a  disposed between the screw bores  16   a  and  18   a . A first leg  22   a  extends from adjacent the screw bore  16   a  while a second leg  24   a  extends from adjacent the screw bore  18   a . When joined, the plate segments  12   a  and  12   b  form an oblong opening or window  30 . Referring additionally to  FIGS. 2 and 3  (showing a top perspective view and a bottom perspective view respectively) a plate segment labeled  12  is shown representing the plate segments  12   a  and  12   b  since they are identical. 
     The leg  22  includes a reception area  34  defined by a partially open, configured slot or channel  40  that terminates in an end wall  58 . The slot  40  includes a cutout, cavity, depression or concavity  42  having a front, sloping ledge  44 . The leg  22  also defines a front surface  54 . 
     The leg  24  includes a retention structure  36  on a front portion of a projection  46  extending beyond a stop surface  56 . The retention structure  36  includes first and second relief slots  48  and  49  that define a flange  50 . The flange  50  has a front lip  52  that extends upward from the surface of the flange  50  and thus the projection  46 . The flange  50  is somewhat resilient in that pressure or force exerted onto the flange  50  through the lip  52  causes the flange  50  to deform or bend slightly in a direction of the applied pressure. Because the flange  50  is resilient, the flange  50  returns to its original position or normal state after the pressure or force upon the lip  52  ceases. 
     The flange  50  is adapted to be received in the cavity  42 . With additional reference to  FIGS. 4A and 4B , as the projection  46  is inserted into the slot  40 , the sides of the slot  40  retain the projection  46  in the slot  40  while the flange  50  bends toward the open area of the slot  40  due to contact with surface  53  of the slot  40 . Further travel of the flange  50  towards the end surface  58  of the slot  40  allows the lip  52  to encounter sloped ledge  44 . Once the lip  52  encounters ledge  44 , the resiliency of the flange  50  causes the flange to bend back (snap) into its original position and thus into the cavity  42 . 
     Travel of two components relative to one another ceases when surface  59  contacts surface  58  and surface  56  contacts surface  54 . As seen in  FIG. 4B , the plate  10  may be limitedly dynamic to the extent that there is distance between the lip  52  and the ledge  44  as represented by the double-headed arrow. The plate  10  may be static if there is no distance between the lip  52  and the ledge  44 . 
     Referring to  FIG. 5 , there is depicted an embodiment of another orthopedic device generally designated  60  in which the present invention may be used. Particularly,  FIG. 5  depicts a two level (2-L) spine plate. The two level spine plate is formed by providing a middle part or component  70  between the components  12   a  and  12   b . The middle component  70  is configured to receive the end components  12   a  and  12   b . The middle component  70  is formed of a body  72  having a first screw bore  74  and a second screw bore  76 . A plate cover bore  78  is disposed between the screw bores  74  and  76 . A first leg  80  extends from one side of the body  72  adjacent the bore  74 . A second leg  82  extends from one side of the body  72  adjacent the bore  74  opposite to that of the first leg  80 . A third leg  84  extends from one side of the body  72  adjacent the bore  76 , while a fourth leg  86  extends from one side of the body  72  adjacent the bore  76  opposite to that of the third leg  84 . The first and third legs  80 ,  84  extend in the same direction while the second and fourth legs  82 ,  86  extend in the same direction. The two level plate  60  thus defines first and second oblong windows  88  and  90 . The window  88  is defined between the middle component  70  and the end component  12   a  while the window  90  is defined between the middle component  70  and the end component  12   b.    
     Referring to  FIGS. 6 and 7 , there is depicted a top perspective view and a bottom plan view, respectively, of the middle component  72 . The leg  80  includes a retention structure  92  on a front portion of a projection  94  extending beyond a stop surface  96 . The retention structure  92  includes first and second relief slots  98  and  99  that define a flange  100 . The flange  100  has a front lip  102  that extends upward from the surface of the flange  100  and thus the projection  96 . The flange  100  is somewhat resilient in that pressure or force exerted onto the flange  100  through the lip  102  causes the flange  100  to deform or bend slightly in a direction of the applied pressure. Because the flange  100  is resilient, the flange  100  returns to its original position or normal state after the pressure or force upon the lip  102  ceases. 
     The leg  82  includes a reception area  126  defined by a partially open, configured slot or channel  128  that terminates in an end wall  136 . The slot  128  includes a cutout  132  having a front, sloping ledge  134 . The leg  82  also defines a front surface  138 . The reception area  126  is configured to receive the retention structure  36   b  of the end component  12   b  in like manner to the reception of the retention structure  36   b  into the reception area  34   a.    
     The leg  84  includes a reception area  130  defined by a partially open, configured slot or channel  140  that terminates in an end wall  146 . The slot  140  includes a cutout  142  having a front, sloping ledge  144 . The leg  84  also defines a front surface  148 . The reception area  130  is configured to receive the retention structure  36   a  of the end component  12   a  in like manner to the reception of the retention structure  36   a  into the reception area  34   b.    
     The leg  86  includes a retention structure  110  on a front portion of a projection  112  extending beyond a stop surface  114 . The retention structure  110  includes first and second relief slots  116  and  117  that define a flange  118 . The flange  118  has a front lip  120  that extends upward from the surface of the flange  118  and thus the projection  112 . The flange  118  is somewhat resilient in that pressure or force exerted onto the flange  118  through the lip  120  causes the flange  118  to deform or bend slightly in a direction of the applied pressure. Because the flange  118  is resilient, the flange  118  returns to its original position or normal state after the pressure or force upon the lip  120  ceases. 
     It can be seen that the middle structure  70  is symmetric about a 180° rotation of itself.  FIG. 8  depicts an underside view of the two level spine plate  60 . 
       FIGS. 9-14  depict various views of another orthopedic implant or device utilizing an embodiment of the present invention and particularly a joining and retaining structure. Referring to  FIG. 9 , there is depicted an orthopedic implant generally designated  160  that is particularly a two-piece, vertebral interbody or intrabody device. The two-piece, vertebral interbody device  160  is representative of the various types of N-piece vertebral interbody devices that may use the present invention. Particularly, pieces of the interbody device are connected to one another via a connection device having resilient snaps or snap structures. The resilient snaps deform when received by an interbody piece, but then return to their original position once received. 
     The interbody device  160  includes a first piece, portion or section  162  and a second piece, portion or section  164  that are joined by a connection device  166 . The first and second pieces  162 ,  164  and the connection device  166  are formed of a bio-compatible material. Also, the nomenclature first and second is arbitrary. 
     The first piece  162  is defined by a generally arced oblong body  168 . The body  168  has a toothed or serrated upper surface  170  and a toothed or serrated lower surface  172 . The nomenclature upper and lower is arbitrary. The body  168  defines an inner cavity  174  and a plurality of side windows. While one end of the body  168  is curved, the other end has an essentially flat face  176 . Anti-rotation features are provided on/in the flat face  176 . Particularly, first and second posts or pegs  178   a ,  178   b  are provided on opposite corners of the face  176 . Additionally, first and second bores  180   a ,  180   b  are provided on opposite corners, opposite to the posts  178   a ,  178   b . A central connection device bore  182  is also provided in the face  176 . 
     The second piece  164  is defined by a generally arced oblong body  184 . The body  184  has a toothed or serrated upper surface  186  and a toothed or serrated lower surface  188 . The nomenclature upper and lower is arbitrary. The body  184  defines an inner cavity  190  and a plurality of side windows. While one end of the body  184  is curved, the other end has an essentially flat face  192  (see, e.g.  FIG. 10 ). Anti-rotation features are provided on/in the face  192 . Particularly, first and second posts or pegs  194   a ,  194   b  are provided on opposite corners of the face  192 . Additionally, first and second bores  196   a ,  196   b  are provided on opposite corners, opposite to the posts  194   a ,  194   b . A central connection device bore  198  is also provided in the face  192 . 
     The posts  178   a ,  178   b  of the body  168  of the first piece  160  are sized and configured to be received in the bores  196   b ,  196   a , respectively, in the face  192  of the body  184  of the second piece  162  when joined. Likewise, the posts  194   a ,  194   b  of the body  184  of the second piece  162  are sized and configured to be received in the bores  180   b ,  180   a , respectively, in the face  176  of the body  168  of the first piece  160  when joined. The reception of posts and bores upon joining of the first and second pieces  160 ,  162  prohibits rotation of one piece relative to another piece (anti-rotation). 
       FIG. 11  particularly depicts the connection device  166  that allows the joining of the first and second pieces  162 ,  164 . The connection device  166  is defined by a generally cylindrical body  200  having a first head or end  202  and a second head or end  204 . The nomenclature first and second is arbitrary. The first and second heads  202 ,  204  are formed as resilient snap structures. The first head  202  has four snaps  206   a ,  206   b ,  206   c ,  206   d  that define an “X” pattern of slots in the first head  202  and respective ledges  207   a ,  207   b ,  207   c ,  207   d . The second head  204  has four snaps  208   a ,  208   b ,  208   c ,  208   d  that define an “X” pattern of slots in the first head  204  and respective ledges  209   a ,  209   b ,  209   c ,  209   d . A portion of each of the snaps  206   a ,  206   b ,  206   c ,  206   d ,  208   a ,  208   b ,  208   c ,  208   d  extend radially beyond the radial dimension of the cylindrical body  200  such that the ledges  207   a ,  207   b ,  207   c ,  207   d ,  209   a ,  209   b ,  209   c ,  209   d  of the respective snaps  206   a ,  206   b ,  206   c ,  206   d ,  208   a ,  208   b ,  208   c ,  208   d  extend radially beyond the radial dimension of the cylindrical body  200  (i.e. the middle portion thereof between the heads  202 ,  204 ). 
     With particular reference to  FIGS. 13 and 14 , the central bore  182  of the first piece  160  and the central bore  198  of the second piece  162  is sized radially to receive the connection device  200 . Particularly, the radial size (diameter) of each central bore  182 ,  198  is sized to cause the snaps  206   a ,  206   b ,  206   c ,  206   d ,  208   a ,  208   b ,  208   c ,  208   d  to deform radially inward during insertion and travel through the bores  182 ,  198  but snugly surround the middle cylindrical portion of the body  200  of the connection device  166 . The length of each of the central bores  182  and  198  is such that the snaps  206   a ,  206   b ,  206   c ,  206   d ,  208   a ,  208   b ,  208   c ,  208   d  will spring or return back to their original position and allow the ledges  207   a ,  207   b ,  207   c ,  207   d ,  209   a ,  209   b ,  209   c ,  209   d  of respective snaps  206   a ,  206   b ,  206   c ,  206   d ,  208   a ,  208   b ,  208   c ,  208   d  to rest against the inner walls of the respective pieces  160 ,  162 . In this manner, the two pieces  160 ,  162  of the interbody device are joined, coupled, or connected. 
     Other orthopedic implants may utilize embodiments of the present invention. For example, spine fixation constructs may utilize the present joining and retaining structure. In one form, a bone screw structure is connected to a rod holder of a rod holder construct via a resilient snap structure. The resilient snap structure of the rod holder expands when a configured head of the bone screw structure is inserted therein and then contracts back to its normal state around the configured head to retain the configured head and thus the bone screw structure. In this embodiment, the spine fixation construct thus includes a bone screw structure and a rod holder construct. A spine rod is retained in and by the rod holder construct and may or may not be considered as part of the spine fixation construct. 
     Another form of a spine fixation construct that utilizes the present joining and retaining structure provides for two bone screw structures, a snap connection plate and two head constructs form. In this embodiment, the two head constructs are coupled to the snap connection plate via cam lock snaps. A construct comprising two head constructs and the snap connection plate is then situated onto the two bone screw structures. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only preferred embodiments has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.