Implantation of magnets in bone to reduce contact pressure

Abstract

Permanent magnets are implanted in bone to unload compressive forces at joints using the repulsive force therebetween. A porous metal container is implanted first and becomes fixed in place by bone growth. The permanent magnet is then inserted in the container and retained in place. A magnet prescription system includes a display and input device which enables a user to alter parameters such as magnet size, strength and placement and calculate and display the repulsive force that will result.

1 . A method for implanting a magnet in a bone, the steps comprising:
 a) inserting a container made of a porous material in the bone at a selected location;   b) waiting for a period of time during which bone grows into the porous material to fix the container in the selected location;   c) inserting a permanent magnet into a cavity formed in the container; and   d) retaining the permanent magnet in the cavity.   
   
   
       2 . The method as recited in  claim 1  in which the permanent magnet is retained in the cavity by fastening a cover to the container which entraps the permanent magnet in the cavity. 
   
   
       3 . The method as recited in  claim 1  in which step a) is performed by drilling a hole in the bone to form a bone tunnel; and
 inserting the container in the bone tunnel.   
   
   
       4 . The method as recited in  claim 3  in which the bone tunnel extends from a bone surface toward a joint formed by the juncture of the bone with another bone and the bone tunnel terminates near the joint. 
   
   
       5 . The method as recited in  claim 1  in which step a) includes:
 i) inserting a second container made of a porous material in a second bone which joins with said bone;   ii) inserting a second permanent magnet into a cavity formed in the second container; and   iii) retaining the second permanent magnet in the second container cavity.   
   
   
       6 . The method as recited in  claim 1  which includes acquiring an image after step a) is performed to determine the location of the container in the bone.