Abstract:
The present invention relates to a knee joint prosthesis including femoral and tibial components. The bodies of the components possess a network of channels which may be used to deliver bone cement to the component bone interface after the components are implanted. The body of the femoral component possesses a network of channels which is in communication with a bore on the distal surface of the component which may be used to deliver bone cement into the network of channels after the component is implanted. The body of the tibial component possesses a network of channels which is in communication with a bore on the proximal surface of the component which may be used to deliver bone cement into the network of channels after the component is implanted. The components are suitable for implantation using arthroscopic as well as open surgical procedures. The components may be used as unicondylar implants in either compartment of the knee or in both compartments of the knee.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to prosthetic implants and, more particularly, to prostheses for human knee joints that are implantable by means of arthroscopic as well as open surgical techniques. 
     2. Description of Related Art 
     It is common to provide implants to resurface worn articular surfaces of knees. Many of the prior art prostheses require large incisions to gain adequate access to the joint space to perform the surgery and the removal of a great deal of bone from the femur and tibia in order to accommodate the implant, thereby causing large amounts of surgical trauma to the patients and reducing the amount of bone available in the event that revision surgery is required. In addition, the removal of too much bone may lead to failure of the implanted prosthesis due to subsidence of the implant into the underlying bone necessitating revision surgery to replace the failed implants. 
     Bone cement is typically used to secure implant components. Misalignment of components may occur when bone cement is placed on the prepared bone surface before the components are implanted into position. When a component is implanted into bone cement which has been placed on the prepared bone surface, bone cement may escape from between the bone and the edges of the implant. When bone cement is injected into a portal located on a side wall of an implant, bone cement may leak from the portal into the joint space. If left in the joint space, such excess or leaked bone cement may cause irritation. On the other hand, inadequate amounts of bone cement may result in inadequate fixation resulting in the loosening of the implant. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is a primary object of the present invention to overcome the above mentioned disadvantages associated with prior art devices and surgical procedures. 
     Another object of the present invention is to reduce surgical trauma by providing prosthetic implants that reduce the required size of surgical incisions and that reduce the amount of bone that must be removed during surgery when compared to prior art devices and surgical procedures. 
     Another object of the present invention is to reduce the leakage of bone cement into the joint space by providing an improved system for delivering bone cement to the interface between the implant and the bone. 
     Another object of the present invention is to reduce the likelihood of subsidence of implants by providing implants that require a minimal resection of bone such that the bone architecture is left intact and better able to adequately support the implants. 
     Another object of the present invention is to provide an implant that, in the event that revision surgery is required, would allow the use of a standard unicompartment replacement knee prosthesis in the revision surgery by providing implants that require a minimal resection of bone such that the bone architecture is left intact leaving more bone stock available for use in revision surgery when compared to prior art devices and surgical procedures. 
     A knee joint prosthesis including femoral and tibial components is disclosed. The body of the femoral component possesses a network of bores which have openings in the proximal surface of the femoral component. The network of bores communicates with an opening formed on the distal surface of the component. The network of bores may be used to deliver bone cement to the implant and bone interface after the implant has been placed in the end of the prepared femur. The body of the tibial component has an internal network of bores in communication with channels or openings formed on the distal surface of the tibial component. The network of bores communicates with an opening formed on the proximal surface of the tibial component. The network of bores may be used to deliver bone cement to the implant and bone interface after the implant has been place in the end of the prepared femur. In another embodiment of the invention, the body of the femoral component possesses a network of bores which is in communication with the bore of a cannulated fastener that attaches the femoral component to a femur. The tibial component possesses a network of grooves formed upon its distal surface which is in communication with a central bore within a post on the distal surface of the tibial component. A cannulated fastener is attached to the post on the distal surface of the tibial component to attach the tibial component to the tibia. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of the distal surface of the femoral component of the present invention. 
         FIG. 2  is a side elevational view of the femoral component of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the femoral component taken along section  3 - 3  of  FIG. 2   
         FIG. 4  is a cross-sectional view of the femoral component taken along section  4 - 4  of  FIG. 2 . 
         FIG. 5  is a view of the proximal surface of the femoral component of  FIG. 1 . 
         FIG. 6  is a side elevational view of the tibial component of the present invention. 
         FIG. 7  is a view of the distal surface of the tibial component. 
         FIG. 8  is a perspective view of a fastener. 
         FIG. 9  is a perspective view of a knee, showing a femur and tibia, into which the femoral and tibial components have been implanted. 
         FIG. 10  is a view of the distal surface of the femoral component of the second embodiment of the femoral component. 
         FIG. 11  is a view of the proximal surface of the second embodiment of the femoral component. 
         FIG. 12  is a view of the proximal surface of the second embodiment of the tibial component. 
         FIG. 13  is a view of the distal surface of the tibial component of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to prosthetic implants and, more particularly, to prostheses for human knee joints that are implantable by means of arthroscopic as well as open surgical techniques. 
     The femoral component  10  of the prosthesis of the present invention is illustrated in  FIG. 1-5 . 
     A distal view of the femoral component  10  is shown in  FIG. 1 . The femoral component  10  may have one or more through holes  12  passing through the distal surface of  16  of the femoral component  10  for receiving a bone screw or other fastener known in the art for attaching the femoral implant  10  to the distal end of a femur. The periphery  28  of the femoral component is continuous, smooth and unbroken by any openings. 
     As shown in  FIG. 2 , the femoral component  10  comprises a curved body portion  14  having a convexly curved distal surface  16  and a concave proximal surface  18 . A plurality of generally transverse bores or holes  20  are formed through the body portion  14  substantially perpendicular to the longitudinal axis of the femoral component. The inner surface  22  of one or more of the transverse bores  20  may be internally threaded or otherwise adapted to receive and attach to the distal end of a fastener. A generally longitudinally oriented bore (not shown) passes through the body portion  14  of the femoral component  10  substantially perpendicular to the transverse bores  20  intersecting the transverse bores  20  causing the transverse bores  20  to be in communication with each other forming an interconnecting network of channels. 
       FIG. 3  shows a cross-sectional view of the body  14  of the femoral implant  10  taken along the line III-III in  FIG. 2 . The femoral implant  10  includes a distal surface  16  configured for contacting the proximal surface  48  of a tibial implant  40  which is shown in  FIG. 6 . The femoral implant  10  may also include an apex portion  18  and support shoulders  24  to engage the prepared distal end of the femur. The apex  18  is shown to be triangular in cross-section, but it may be rounded, squared, or other geometric shape. The apex portion  18  may be configured to be received in the cancellous bone material of the femur, whereas the supports  24  may be configured to contact the cortical bone material of the femur, so that load sharing between the cortical bone and the cancellous bone may be accomplished. The body  14  contains a portion of the central bore  26  which intersects the transverse bores  20  causing the transverse bores  20  to be in communication with each other forming an interconnecting network of channels. 
       FIG. 4  shows a cross-sectional view of the body  14  of the femoral implant  10  taken along the line IV-IV in  FIG. 2 . The femoral implant  10  includes a distal surface  16  configured for contacting the proximal surface  48  of a tibial implant  40  which is shown in  FIG. 6 . The femoral implant  10  may also include an apex portion  18  and support shoulders  24  to engage the prepared distal end of the femur. The apex portion  18  may be configured to be received in the cancellous bone material of the femur, whereas the supports  24  may be configured to contact the cortical bone material of the femur, so that load sharing between the cortical bone and the cancellous bone may be accomplished. The body  14  contains a transverse bore  20  which is intersected by a portion of the generally perpendicular central bore  26 . 
       FIG. 5  shows a proximal view of the femoral component  10  illustrating the plurality of generally transverse bores or holes  20  formed through the body portion  14  substantially perpendicular to the longitudinal axis of the femoral component  10 . The inner surface  22  of one transverse bore  20  may be internally threaded or otherwise adapted to receive and attach to the distal end of a fastener. A generally longitudinally oriented bore (not shown) passes through the body portion  14  of the femoral component  10  substantially perpendicular to the transverse bores  20  intersecting the transverse bores  20  causing the transverse bores  20  to be in communication with each other forming an interconnecting network of channels. The generally longitudinally oriented bore may intersect the through hole  12  causing the through hole  12  to be in communication with the interconnecting network of channels formed by the longitudinally oriented bore and the transverse bores  20 . 
     The femoral implant  10  may be used to repair a single condyle, referred to as a unicondylar replacement. Also, two femoral implants  10  may be used in a bi-condylar replacement within the scope of the present invention. 
     The femoral component  10  may be shaped to reproduce the weight bearing articular surface of the knee. Moreover, it will be understood that the femoral implant  10  may be implanted without resurfacing the entire width of the condyle. Accordingly, the femoral implant  10  may form a narrow rim on the condyle which may cooperate with the remaining portion of the condyle. The femoral component  10  may be made of a high molecular weight polyethylene (HMWPE), other polymer, metal, or any other suitable material known to those skilled in the art. 
     As shown in  FIG. 6 , the tibial implant component  40  may have a concave proximal surface  48  and a convex distal surface  46 . A post  42  extends distally from the distal surface  46 . The post  42  has a central bore  44  that extends to and communicates with a longitudinal groove on the distal surface of the tibial component  40  (which is shown in  FIG. 7  as longitudinal groove  52 ). The inner surface of the central bore  44  may be internally threaded or otherwise adapted to receive and attach to the distal end of a fastener. A plurality of generally transverse grooves  50  are formed on the distal surface  46  of the tibial implant component  40 . The transverse grooves  50  are substantially perpendicular to the longitudinal groove  52 . The transverse grooves  50  intersect the longitudinal groove  52  resulting in the transverse grooves  50  and the longitudinal groove being in communication with each other forming an interconnecting network of grooves. 
     As shown in  FIG. 7 , a post  42  projects distally from the distal surface  46  of the tibial implant  40 . The post  42  has a central bore  44  that extends to and communicates with a longitudinal groove  52  on the distal surface of the tibial component  40 . The inner surface of the central bore  44  may be internally threaded or otherwise adapted to receive and attach to the distal end of a fastener. A plurality of generally transverse grooves  50  are formed on the distal surface  46  of the tibial implant component  40 . The transverse grooves  50  are substantially perpendicular to the longitudinal groove  52 . The transverse grooves  50  intersect the longitudinal groove  52  resulting in the transverse grooves  50  and the longitudinal groove being in communication with each other forming an interconnecting network of grooves. The post  42  has openings  54  at the base of the post where it is attached to the distal surface  46  of the tibial implant  40  to permit communication between the inner bore  44  of the post  42  to communicate with the longitudinal groove  52 . The periphery  58  of the tibial component  40  is continuous, smooth and unbroken by any openings. 
       FIG. 8  is a perspective view of a screw or fastener  60  which may have a first and second portion, wherein said first portion may comprise a head portion  66  having a recessed portion  68  wherein the recessed portion may comprise a polygonal shape and a second portion, wherein said second portion  64  may comprise an elongate shaft suitable for insertion into a substrate and wherein said shaft may comprise a distal end  62  bearing external threads or other means to attach to the inner surface  22  of a transverse bore  20  of the femoral component  10  or the inner bore  44  of the post  42  of the tibial component  40 . The screw or fastener  60  may be cannulated to permit the injection of bone cement into the network of bores in the femoral component  10  and the network of grooves in the tibial component  40 . 
       FIG. 9  is a perspective view of a knee, showing a femur  70  and tibia  72 , into which a femoral component  10  and a tibial component  40  have been implanted. A bone screw or other fastener has been inserted into the hole in the distal surface of the femoral component  10  to secure the femoral component to the femur  70 . An opening  74  of a bore for a fastener to attach to the proximal surface of the femoral component is shown on the external surface of the femur  70 . An opening  76  of a bore for a fastener to attach to the distal surface of the tibial component is shown on the external surface of the tibia  72 . 
     The tibial implant  40  may be formed of metal, polymer, or any other suitable material known to those skilled in the art. 
     A second embodiment of the femoral component is illustrated in  FIG. 10  and  FIG. 11 . In this second embodiment, one or more flanges  118  are added to the periphery of the femoral component illustrated in  FIG. 1  through  FIG. 5   
     A distal view of the femoral component  110  is shown in  FIG. 10 . The femoral component  110  may have one or more through holes  112  passing through the distal surface of  116  of the femoral component  110  for receiving a bone screw or other fastener known in the art for attaching the femoral component  110  to the distal end of a femur. The periphery  128  of the femoral component  110  is continuous, smooth and unbroken by any openings. Flange  118  is shown extending from the periphery  128  of the femoral component  110 . The flange  118  may have one or more through holes  130  for receiving a bone screw or other fastener for attaching the femoral component  110  to the distal end of a femur. 
       FIG. 11  shows a proximal view of the femoral component  110  illustrating the plurality of generally transverse bores or holes  120  formed through the body portion  114  substantially perpendicular to the longitudinal axis of the femoral component  110 . A generally longitudinally oriented bore (not shown) passes through the body portion  114  of the femoral component  110  substantially perpendicular to the transverse bores  120  intersecting the transverse bores  120  causing the transverse bores  120  to be in communication with each other forming an interconnecting network of channels. The generally longitudinally oriented bore may intersect the through hole  112  causing the through hole  112  to be in communication with the interconnecting network of channels formed by the longitudinally oriented bore and the transverse bores  120 . Flange  118  is shown extending from the periphery  128  of the femoral component  110 . The flange  118  may have one or more through holes  130  for receiving a bone screw or other fastener for attaching the femoral component  110  to the distal end of a femur. The distal surface of flange  118  may include a bore which passes into the longitudinal bore or into the transverse bores  120  causing the bore on the distal surface to be in communication with the interconnecting network of channels. The opening of the bore on the distal surface of flange  118  may be the opening of a through hole  130  or may be separate. The femoral implant  110  may include support shoulders  124  to engage the prepared distal end of the femur. 
       FIG. 12  is a proximal view of a second embodiment of the tibial component. The tibial component  140  when viewed from above is generally semi-circular in shape with a curved wall  144  and a generally straight wall  148 . The proximal surface  150  of the tibial component is slightly concave. The tibial component  140  may have a hole  154  in the proximal surface  150  for receiving a bone screw or other fastener known in the art for attaching the tibial component  140  to the tibia. Hole  154  may pass through the tibial component  140  from the proximal surface  150  to the distal surface. Hole  154  may pass into a bore (not shown) formed within the tibial component causing the hole  154  on the proximal surface to be in communication with an interconnecting network of channels (not shown) formed within the tibial component  140 . 
     Flange  158  may extend from the straight wall  148 . The flange  158  may have a hole  162  for receiving a bone screw or other fastener for attaching the tibial component  140  to the tibia. Hole  162  may pass through the flange  158  from the proximal surface  150  to the distal surface. Hole  162  may pass into a bore (not shown) formed within the flange  158  interconnects with a network of channels (not shown) formed within the tibial component  140  causing the bore on the proximal surface to be in communication with the interconnecting network of channels. 
       FIG. 13  is a distal view of the tibial component  140  of  FIG. 12 . Hole  154  may pass through the tibial component  140 . Flange  158  may extend from the straight wall  148 . The distal surface  164  of the tibial component  140  is slightly convex. Longitudinal grooves  166  on the distal surface of the tibial component  140  are in communication with each other by a bore (not shown) which passes longitudinally through the tibial component  140 . A plurality of generally transverse grooves  168  are formed on the distal surface  164  of the tibial implant component  140  are in communication with each other by transverse bores (not shown) which pass transversely through the tibial component  140 . The transverse grooves  168  are substantially perpendicular to the longitudinal grooves  166 . The transverse bores intersect the longitudinal bore resulting in interconnecting network of bores. 
     In the preferred embodiment of the invention, the body of the femoral component possesses a network of bores which is in communication with a bore on the distal surface of the component. The cannulation permits bone cement to be injected into the network of bores and into the interface between the proximal surface of the femoral component and the prepared distal surface of the femur after the femoral component has been implanted. Following injection of the bone cement, the opening on the distal surface may be sealed by inserting an appropriately sized bone screw or other fastener through the opening into the femur or by placing a cap or plug into the opening. 
     The tibial component possesses a network of grooves formed upon its distal surface which is in communication with a network of bores formed within the body of the tibial component. The network of bores is in communication with an opening on the proximal surface of the tibial component. The opening on the proximal surface of the tibial component permits bone cement to be injected through the network of bores into the network of grooves which are formed within the distal surface of the tibial component and into the interface between the distal surface of the tibial component and the proximal surface of the prepared tibial after the tibial component has been implanted. Following injection of the bone cement, the opening on the proximal surface may be sealed by inserting an appropriately sized bone screw or other fastener through the opening into the tibia or by placing a cap or plug into the opening. 
     It is to be understood that various changes in the details, materials, steps, and arrangements of parts, which have been herein described and illustrated in order to describe the nature of the knee joint prosthesis, may be made by those skilled in the art within the principle and scope of the invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention. Thus, while the present disclosure has been shown in the drawings and described above with particularity and detail, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.