Modular Prosthesis and Locking Nut Therefor

Abstract

A modular prosthesis is provided having a first and second prosthesis component and a locking nut. The first prosthesis component is configured to include a mating surface and a threaded shaft extending from the mating surface. The locking nut is formed to include a distal end having a shaped surface. The second prosthesis component is configured to include a mating surface, a nut-receiving cavity and a bore. The mating surface of the second prosthesis component is configured to mate with the mating surface of the first prosthesis component. The nut-receiving cavity is configured to receive the locking nut therein and to have a shaped bottom wall configured to engage the shaped surface of the locking nut. The bore communicates with the nut-receiving cavity through the shaped bottom wall and the mating surface and is sized to receive the threaded shaft therethrough. The threaded shaft, locking nut, bore and cavity are configured so that when the threaded shaft of the first prosthesis extends through the bore and the locking nut is received in the nut-receiving cavity and tightened onto the threaded shaft, the distal end of the locking nut is urged into engagement in multiple locations with the bottom wall of the cavity and the mating surfaces of the first and second components are urged into engagement.

1 . A modular prosthesis comprising:
 a first prosthesis component configured to include a first half of a male/female connecting joint and a threaded shaft;   a second prosthesis component configured to include a second half of a male/female connecting joint, a nut-receiving cavity configured to receive a locking nut therein and having a shaped bottom surface and a bore communicating with the cavity through the shaped bottom surface and the second half of the male/finale connecting joint and sized to receive the threaded shaft therethrough when the first and second half of the connecting joint are mated;   a locking nut configured to be received on the threaded shaft and formed to include a distal end having a shape configured to engage the shaped bottom surface of the nut receiving cavity; and   wherein the threaded shaft, locking nut, bore and cavity are configured so that when the locking nut is tightened onto the threaded shaft the distal end of the locking nut is urged into engagement in multiple locations with the bottom surface of the cavity.   
     
     
         2 . The device of  claim 1 , wherein the first component is a distal component configured to be received in the medullary canal of a bone and is formed to include a male joint component. 
     
     
         3 . The device of  claim 2 , wherein the second component is formed to include a female joint component configured to mate with the male joint component. 
     
     
         4 . The device of  claim 3 , wherein the shaped bottom surface of the locking nut and the shaped bottom surface of the nut-receiving cavity are both curved. 
     
     
         5 . The device of  claim 4 , wherein the shaped bottom surface of the locking nut and the shaped bottom surface of the nut-receiving cavity each exhibit substantially the same uniform radius of curvature. 
     
     
         6 . The device of  claim 5 , wherein the male joint component and female joint component mate to form a Morse-type taper joint. 
     
     
         7 . The device of  claim 4 , wherein the shaped bottom surface of the locking nut and the shaped bottom surface of the nut-receiving cavity both include multiple radii of curvatures. 
     
     
         8 . The device of  claim 1 , wherein the shaped bottom surface of the locking nut and the shaped bottom surface of the nut-receiving cavity are both curved. 
     
     
         9 . The device of  claim 8 , wherein the shaped bottom surface of the locking nut and the shaped bottom surface of the nut-receiving cavity each exhibit substantially the same uniform radius of curvature. 
     
     
         10 . The device of  claim 8 , wherein the shaped bottom surface of the locking nut and the shaped bottom surface of the nut-receiving cavity both include multiple radii of curvatures. 
     
     
         11 . The device of  claim 1  and further comprising a radiused junction surface formed between the shaped bottom surface of the nut-receiving cavity and the bore. 
     
     
         12 . A modular prosthesis comprising:
 a first prosthesis component configured to include a mating surface and a threaded shaft extending from the mating surface;   a locking nut formed to include a distal end having a shaped surface;   a second prosthesis component configured to include a mating surface configured to mate with the mating surface of the first prosthesis component, a nut-receiving cavity configured to receive the locking nut therein and having a shaped bottom wall configured to engage the shaped surface of the locking nut and a bore communicating with the nut-receiving cavity through the shaped bottom wall and the mating surface and sized to receive the threaded shaft therethrough; and,   wherein the threaded shaft, locking nut bore and cavity are configured so that when the threaded shaft of the first prosthesis extends through the bore and the locking nut is received in the nut-receiving cavity and tightened onto the threaded shaft, the distal end of the locking nut is urged into engagement in multiple locations with the bottom wall of the cavity and the mating surfaces of the first and second components are urged into engagement.   
     
     
         13 . The device of  claim 12 , wherein the shaped surface of the locking nut and the shaped bottom wall of the nut-receiving cavity are both curved. 
     
     
         14 . The device of  claim 13 , wherein the shaped surface of the locking nut and the shaped bottom wall of the nut-receiving cavity each exhibit substantially the same uniform radius of curvature. 
     
     
         15 . The device of  claim 14 , wherein the shaped surface of the locking nut and the shaped bottom wall of the nut-receiving cavity both include multiple radii of curvatures. 
     
     
         16 . A modular prosthesis comprising:
 a distal prosthesis component configured to include a male joint component, a threaded shaft, a stem and an axis, wherein the male joint component and threaded shaft are formed concentrically about the axis and wherein the threaded shaft extends proximally from the male joint component and the stem extends distally from the male joint component;   a locking nut configured to be received on the threaded shaft and formed to include a radiused distal end;   a proximal prosthesis component comprising a body having a longitudinal axis, the body being configured to include a female joint component configured to mate with the male joint component, a nut-receiving cavity and a shaft-receiving bore formed concentrically about the longitudinal axis, wherein the nut-receiving cavity is configured to receive the locking nut therein and includes a radiused bottom surface configured for engagement in multiple locations with the radiused distal end of the looking nut and the bore is sized to receive the threaded shaft therein, communicates with the nut-receiving cavity through the radiused bottom surface and communicates with the female joint component; and   wherein the threaded shaft, locking nut, bore and cavity are configured so that when the locking nut is tightened onto the threaded shaft the radiused distal end of the locking nut is urged into engagement in multiple locations with the radiused bottom surface of the cavity.   
     
     
         17 . The modular prosthesis of  claim 16 , and further comprising:
 a plurality of differently sized distal prosthesis components each configured to include a male joint component, a threaded shaft, a stem and an axis, wherein the male joint component and threaded shaft are formed concentrically about the axis and wherein the threaded shaft extends proximally from the male joint component and the stem extends distally from the male joint component, wherein the stem of each of the plurality of distal prosthesis components is a different size than the stems of the other of the plurality of distal prosthesis components but the male joint components of all of the plurality of distal prosthesis components are the same size;   a plurality of proximal prosthesis components each comprising a body having a longitudinal axis, the body being configured to include a female joint component configured to mate with the male joint component, a nut-receiving cavity and a shaft-receiving bore formed concentrically about the longitudinal axis, wherein the nut-receiving cavity is configured to receive the locking nut therein and includes a radiused bottom surface and the bore is sized to receive the threaded shaft therein, communicates with the nut-receiving cavity through the radiused bottom surface and communicates with the female joint component, wherein the body of each of the plurality of proximal prosthesis components is a different size than the body of the other of the plurality of proximal prosthesis components but the female joint components of all of the plurality of proximal prosthesis components are the same size.   
     
     
         18 . The modular prosthesis of  claim 17 , and further comprising a plurality of locking nuts each having a diameter and a length and configured to be received on the threaded shaft of each of the plurality distal prosthesis components and formed to include a radiused distal end, wherein the diameter of each of the plurality of locking nuts is the same as the diameter of the other of the plurality of locking nuts and the length of each of the plurality of locking nuts is different from the length of each of the other of the plurality of locking nuts; and wherein the nut-receiving cavity of each of the plurality of proximal prosthesis components includes a diameter and a depth, wherein the diameter of the nut-receiving cavity of each of the plurality of proximal prosthesis components is the same as the diameter of the nut-receiving cavity of the other of the plurality of proximal prosthesis components and the depth of the nut-receiving cavity of each of the plurality of proximal prosthesis components is different from the depth of the nut-receiving cavity of each of the other of the plurality of proximal prosthesis components. 
     
     
         19 . The modular prosthesis of  claim 18  wherein each of the plurality of locking nuts is associated with a different one of the plurality of proximal prosthesis components. 
     
     
         20 . The modular prosthesis of  claim 19  wherein the length of the associated one of the plurality of locking nuts is substantially equal to the depth of the nut-receiving cavity of its associated one of the plurality of proximal prosthesis components. 
     
     
         21 . The modular prosthesis of  claim 16  and further comprising a radiused junction surface formed between the radiused bottom surface of the nut-receiving cavity and the bore.