Radial Head Replacement System

Abstract

A radial head replacement system includes a radial head replacement, an apparatus for guiding the resection of a radial head, and a kit including bone plug and bone plug insertion instrument. The radial head replacement has a separate adjustable head portion that may be secured on an implanted stem such that the implanted radial head replacement smoothly interfaces with the capitellum of the humerus. In another form, the radial head replacement uses crossed bone screws that serve to more securely anchor the stem of the radial head replacement in the intramedullary canal of the radius. The resection guide includes a movable cutting guide which ensures a precise resection of the radial head and thereby allows for better positioning of the implanted radial head replacement. The bone plug limits the travel of bone cement beyond the area of affixation of the stem portion of a radial head replacement to the radius.

1 . A prosthesis for replacing an end portion of a bone, the prosthesis comprising:
 a head, a stem extending away from the head, a first screw, and a second screw,   wherein the stem is dimensioned to be received in the intramedullary canal of the bone, the prosthesis includes a first channel extending diagonally from a first side of the head to an opposite second side of the stem, the prosthesis includes a second channel extending diagonally from a second side of the head to an opposite first side of the stem, the first screw is associated with and arranged in the first channel and the second screw is associated with and arranged in the second channel such that the prosthesis can be secured to the bone by driving the first screw arranged in the first channel into the bone and driving the second screw arranged in the second channel into the bone.   
   
   
       2 . The prosthesis of  claim 1  wherein:
 the first screw has a length greater than the first channel, and   the second screw has a length greater than the second channel.   
   
   
       3 . The prosthesis of  claim 1  wherein:
 the prosthesis replaces a radial head.   
   
   
       4 . The prosthesis of  claim 3  wherein:
 the head of the prosthesis is elliptical, and   the outer wall of the head of the prosthesis includes a concave surface dimensioned to interface with the capitellum of the humerus and a periphery surface dimensioned to interface with the radial notch of the ulna when the prosthesis is secured to the bone.   
   
   
       5 . The prosthesis of  claim 4  wherein:
 the concave surface is surrounded by a rim.   
   
   
       6 . The prosthesis of  claim 1  wherein:
 the head and stem are integral.   
   
   
       7 . The prosthesis of  claim 1  wherein:
 the first channel has internal threads.   
   
   
       8 . The prosthesis of  claim 7  wherein:
 the second channel has internal threads.   
   
   
       9 . The prosthesis of  claim 1  wherein:
 the first channel is not threaded, and   the first screw is self-tapping.   
   
   
       10 . The prosthesis of  claim 9  wherein:
 the second channel is not threaded, and   the second screw is self-tapping.   
   
   
       11 . A kit for replacing a radial head, the kit comprising:
 a radial head replacement including a head and a stem extending away from the head, the stem being dimensioned to be received in the intramedullary canal of the radius, the radial head replacement including a first channel extending diagonally from a first side of the head to an opposite second side of the stem, the radial head replacement including a second channel extending diagonally from a second side of the head to an opposite first side of the stem.   
   
   
       12 . The kit of  claim 11  further comprising:
 a first screw dimensioned to be arranged in the first channel such that the radial head replacement can be secured to the radius by driving the first screw arranged in the first channel into the radius, and   a second screw dimensioned to be arranged in the second channel such that the radial head replacement can be secured to the radius by driving the second screw arranged in the second channel into the radius.   
   
   
       13 . The kit of  claim 12  wherein:
 the radial head replacement is provided with the first screw partially inserted in the first channel and with the second screw partially inserted in the second channel.   
   
   
       14 . The kit of  claim 1  wherein:
 the head of the radial head replacement is elliptical, and   the outer wall of the head of the radial head replacement includes a concave surface dimensioned to interface with the capitellum of the humerus and a periphery surface dimensioned to interface with the radial notch of the ulna when the radial head replacement is secured to the radius.   
   
   
       15 . The kit of  claim 14  wherein:
 the concave surface is surrounded by a rim.   
   
   
       16 . The kit of  claim 11  wherein:
 the head and stem are integral.   
   
   
       17 . The kit of  claim 11  wherein:
 the first channel has internal threads.   
   
   
       18 . The kit of  claim 17  wherein:
 the second channel has internal threads.   
   
   
       19 . The kit of  claim 12  wherein:
 the first channel is not threaded, and   the first screw is self-tapping.   
   
   
       20 . The kit of  claim 19  wherein:
 the second channel is not threaded, and   the second screw is self-tapping.