Ball and socket bearing for artificial joint

Abstract

A ball and socket joint for implanting in the body is provided wherein the socket portion of the joint can have various orientations with respect to the patient's anatomy, and the orientation used for a particular patient can be selected and/or changed in situ, that is, during or after implantation of the joint. In addition, the configuration of the joint, e.g., constrained versus semi-constrained, as well as the materials making up the socket portion of the joint, e.g., plastic versus metal, can be selected and/or changed in situ. The questions raised in reexamination request Nos. 90/004,732, filed Aug. 26, 1997 and 90/005,596, filed Jun. 22, 1999, have been considered and the results are reflected in this reissue.

What is claimed is:  
     
       1. A ball and socket joint for implantation in a patient's body comprising a ball portion and a socket portion, 
       the ball portion including:  
       a ball; and  
       first fixation means for attachment to a first bony structure, said fixation means being connected to said ball by a neck element; and  
       the socket portion including:  
       a bearing for receiving having an inner bearing surface configured to receive and surround a portion of the ball wherein the ball in combination with the neck element are free to move within the bearing in a plurality of directions;  
       second fixation means for attachment to a second bony structure, said second fixation means having a cavity for receiving the bearing, said cavity having an opening defining a first plane through which the bearing enters the cavity; and  
       means for securing the bearing to the second fixation means in any one of a plurality of selectable orientations after the second fixation means has been attached to the second bony structure, said plurality of selectable orientations being angularly displace displaced from one another about an axis which is perpendicular to the first plane defined by the opening of the cavity of the second fixation means ;  
       the bearing being having a configuration which is non-symmetric with regard to rotation about said axis and such that the angular range of motion of the ball with the neck element within the bearing relative to the axis is smaller in at least one first direction than in at least one other direction, said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said second fixation means in such a preferred orientation after said second fixation means has been attached to the second bony structure.  
     
     
       2. The ball and socket joint of  claim 1  wherein the means for securing comprises bayonet spaces and lugs. 
     
     
       3. The ball and socket joint of  claim 1  wherein the means for securing includes two coaxial pin members and the bearing includes two coaxial cylindrical surfaces which receive the pin members, the pin members and the cylindrical surfaces allowing the bearing to rotate within the cavity of the second fixation means about a single axis, said single axis being orthogonal to the axis which defines the plurality of selectable angular orientations, the orientation of the single axis with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said at least one first direction being orthogonal to the single axis. 
     
     
       4. The ball and socket joint of  claim 1  wherein the bearing includes a lip to restrain dislocations of the ball from the bearing, the orientation of said lip with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said at least one first direction being in the direction of said lip. 
     
     
       5. A prosthesis for implantation in a patient's body comprising: 
       a bearing for receiving having an inner bearing surface configured to receive and surround a portion of the ball portion of a ball and socket joint, said ball being connected to a neck element and the ball in combination with the neck element being free to move within the bearing in a plurality of directions in the assembled joint;  
       fixation means for attachment to a bony structure, said fixation means having a cavity for receiving the bearing, said cavity having an opening defining a first plane through which the bearing enters the cavity; and  
       means for securing the bearing to the fixation means in any one of a plurality of selectable orientations after the fixation means has been attached to the bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the first plane defined by the opening of the cavity of the fixation means ;  
       the bearing being having a configuration which is non-symmetric with regard to rotation about said axis and such that, in the assembled joint, the angular range of motion of the ball with the neck element within the bearing relative to the axis is smaller in at least one first direction than in at least one other direction, said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said fixation means in such a preferred orientation after said fixation means has been attached to the bony structure.  
     
     
       6. The prosthesis of  claim 5  wherein the means for securing comprises bayonet spaces and lugs. 
     
     
       7. The prosthesis of  claim 5  wherein the means for securing includes two coaxial pin members and the bearing includes two coaxial cylindrical surfaces which receive the pin members, the pin members and the cylindrical surfaces allowing the bearing to rotate within the cavity of the fixation means about a single axis, said single axis being orthogonal to the axis which defines the plurality of selectable angular orientations, the orientation of the single axis with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said at least one first direction being orthogonal to the single axis. 
     
     
       8. The prosthesis of  claim 5  wherein the bearing includes a lip to restrain dislocations of the ball from the bearing, the orientation of said lip with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said at least one first direction being in the direction of said lip. 
     
     
       9. A ball and socket joint for implantation in a patient's body comprising a ball portion and a socket portion, 
       
         the ball portion including:  
       
       
         a ball; and  
       
       
         first fixation means for attachment to a first bony structure, said fixation means being connected to said ball; and  
       
       
         the socket portion including:  
       
       
         a bearing for receiving the ball;  
       
       
         second fixation means for attachment to a second bony structure, said second fixation means having a cavity for receiving the bearing, said cavity having an opening defining a plane through which the bearing enters the cavity; and  
       
       
         means for securing the bearing to the second fixation means in any one of a plurality of selectable orientations after the second fixation means has been attached to the second bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the plane defined by the opening of the cavity of the second fixation means, said means for securing comprising bayonet spaces and lugs;  
       
         the bearing being non - symmetric with regard to rotation about said axis and said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said second fixation means in such a preferred orientation after said second fixation means has been attached to the second bony structure.    
     
     
       10. A ball and socket joint for implantation in a patient's body comprising a ball portion and a socket portion, 
       
         the ball portion including:  
       
       
         a ball; and  
       
       
         first fixation means for attachment to a first bony structure, said fixation means being connected to said ball; and  
       
       
         the socket portion including:  
       
       
         a bearing for receiving the ball;  
       
       
         second fixation means for attachment to a second bony structure, said second fixation means having a cavity for receiving the bearing, said cavity having an opening defining a plane through which the bearing enters the cavity; and  
       
       
         means for securing the bearing to the second fixation means in any one of a plurality of selectable orientations after the second fixation means has been attached to the second bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the plane defined by the opening of the cavity of the second fixation means;  
       
         the bearing being non - symmetric with regard to rotation about said axis and said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said second fixation means in such a preferred orientation after said second fixation means has been attached to the second bony structure, the means for securing including two coaxial pin members and the bearing including two coaxial cylindrical surfaces which receive the pin members, the pin members and the cylindrical surfaces allowing the bearing to rotate within the cavity of the second fixation means about a single axis, said single axis being orthogonal to the axis which defines the plurality of selectable angular orientations, the orientation of the single axis with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations.    
     
     
       11. A ball and socket joint for implantation in a patient's body comprising a ball portion and a socket portion, 
       
         the ball portion including:  
       
       
         a ball; and  
       
       
         first fixation means for attachment to a first bony structure, said fixation means being connected to said ball; and  
       
       
         the socket portion including:  
       
       
         a bearing for receiving the ball;  
       
       
         second fixation means for attachment to a second bony structure, said second fixation means having a cavity for receiving the bearing, said cavity having an opening defining a plane through which the bearing enters the cavity; and  
       
       
         means for securing the bearing to the second fixation means in any one of a plurality of selectable orientations after the second fixation means has been attached to the second bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the plane defined by the opening of the cavity of the second fixation means;  
       
         the bearing being non - symmetric with regard to rotation about said axis and said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said second fixation means in such a preferred orientation after said second fixation means has been attached to the second bony structure, the bearing including a lip to restrain dislocations of the ball from the bearing, the orientation of said lip with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations.    
     
     
       12. A prosthesis for implantation in a patient's body comprising: 
       
         a bearing for receiving the ball portion of a ball and socket joint;  
       
       
         fixation means for attachment to a bony structure, said fixation means having a cavity for receiving the bearing, said cavity having an opening defining a plane through which the bearing enters the cavity; and  
       
       
         means for securing the bearing to the fixation means in any one of a plurality of selectable orientations after the fixation means has been attached to the bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the plane defined by the opening of the cavity of the fixation means, said means for securing comprising bayonet spaces and lugs;  
       
         the bearing being non - symmetric with regard to rotation about said axis and said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said fixation means in such a preferred orientation after said fixation means has been attached to the bony structure.    
     
     
       13. A prosthesis for implantation in a patient's body comprising: 
       
         a bearing for receiving the ball portion of a ball and socket joint;  
       
       
         fixation means for attachment to a bony structure, said fixation means having a cavity for receiving the bearing, said cavity having an opening defining a plane through which the bearing enters the cavity; and  
       
       
         means for securing the bearing to the fixation means in any one of a plurality of selectable orientations after the fixation means has been attached to the bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the plane defined by the opening of the cavity of the fixation means;  
       
         the bearing being non - symmetric with regard to rotation about said axis and said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said fixation means in such a preferred orientation after said fixation means has been attached to the bony structure, the means for securing including two coaxial pin members and the bearing including two coaxial cylindrical surfaces which receive the pin members, the pin members and the cylindrical surfaces allowing the bearing to rotate within the cavity of the fixation means about a single axis, said single axis being orthogonal to the axis which defines the plurality of selectable angular orientations, the orientation of the single axis with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations.    
     
     
       14. A prosthesis for implantation in a patient's body comprising: 
       
         a bearing for receiving the ball portion of a ball and socket joint;  
       
       
         fixation means for attachment to a bony structure, said fixation means having a cavity for receiving the bearing, said cavity having an opening defining a plane through which the bearing enters the cavity; and  
       
       
         means for securing the bearing to the fixation means in any one of a plurality of selectable orientations after the fixation means has been attached to the bony structure, said plurality of selectable orientations being angularly displaced from one another about an axis which is perpendicular to the plane defined by the opening of the cavity of the fixation means;  
       
         the bearing being non - symmetric with regard to rotation about said axis and said lack of symmetry making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations, said means for securing allowing said bearing to be secured to said fixation means in such a preferred orientation after said fixation means has been attached to the bony structure, the bearing including a lip to restrain dislocations of the ball from the bearing, the orientation of said lip with respect to the anatomy of the patient's body making at least one of the selectable angular orientations of the bearing more preferred for physiological reasons than others of said angular orientations.