Modular prosthesis and use thereof for replacing a radial head

Abstract

A modular prosthesis system for replacement of a head portion of a proximal radius includes a monolithic stem component, a head component, and a locking mechanism formed by the stem and head components. The stem component defines a stem anchoring portion having a longitudinal axis and configured to couple to the proximal radius, and a dovetail-shaped first mounting portion on a first end face that extends in a first direction transverse to the longitudinal axis. The head component has a dovetail-shaped second mounting portion on a second end face opposite the first end face slidably engaged with the first mounting portion along the first direction. One of the first and second mounting portions intersects the longitudinal axis. The locking mechanism is formed at an interface between the stem and head components and is engaged through relative translational movement between the stem and head components. A related method is provided.

1 . A method of coupling a modular radial head prosthesis to a resected radius, comprising:
 inserting an anchoring portion of a stem having a longitudinal axis component into the resected radius, said stem having a first coupling portion and first and second sides which are generally parallel to the longitudinal axis;   coupling a head component having a first mounting portion that extends in a first direction transverse to the longitudinal axis of the first coupling portion;   coupling a first arm of an insertion tool having a first force transmitting surface to the head component;   coupling a second arm of the insertion tool having a second force transmitting surface to the second side;   slidably translating the first mounting portion with a second mounting portion on the stem by moving the first arm in the first direction transverse to the longitudinal axis;   sliding the head component with respect to the stem component by moving the head component in the first direction; and   locking the head component to the anchor portion.   
     
     
         2 . The method according to  claim 1 , further comprising slidably engaging the head until a locking mechanism formed by the stem component and the head component at an interface is engaged. 
     
     
         3 . The method according to  claim 1 , wherein one of the first and second mounting portions intersects the longitudinal axis. 
     
     
         4 . The method according to  claim 1 , wherein slidably engaging the first mounting portion is engaging the resected radius. 
     
     
         5 . The method according to  claim 1 , wherein the first force transmitting surface is a cylindrical surface. 
     
     
         6 . The method according to  claim 1 , wherein the second force transmitting surface is a hook shaped member. 
     
     
         7 . The method according to  claim 1 , further comprising coupling the first member to the second member through a hinge joint. 
     
     
         8 . The method according to  claim 1 , wherein the first and second members are parallel. 
     
     
         9 . A method of coupling a modular radial head prosthesis to a resected radius, comprising:
 inserting a stem having a longitudinal axis into a resected radius, said stem having a first coupling portion having an axis perpendicular the longitudinal axis and first and second opposed sides;   coupling a head component having second mounting portion to the first coupling portion;   coupling a first force transmitting surface of a first arm of an insertion tool to the head component;   coupling a second force transmitting surface of a second arm of the insertion tool having to the second side;   slidably displacing the first mounting portion with respect to the second mounting portion by moving the first arm in a first direction transverse to the longitudinal axis thereby applying a force on the head which is generally parallel and opposite a force on the stem so as to cause the head component to be displaced with respect to the stem component in the first direction.   
     
     
         10 . The method according to  claim 9 , further comprising slidably engaging the head until a locking mechanism formed by the stem component and the head component at an interface is engaged. 
     
     
         11 . The method according to  claim 9 , wherein one of the first and second mounting portions intersects the longitudinal axis. 
     
     
         12 . The method according to  claim 9 , wherein slidably engaging the first mounting portion is engaging the resected radius. 
     
     
         13 . The method according to  claim 9 , wherein the first force transmitting surface is a cylindrical surface. 
     
     
         14 . The method according to  claim 9 , wherein the second force transmitting surface is a hook shaped member. 
     
     
         15 . The method according to  claim 9 , further comprising coupling the first arm to the second arm. 
     
     
         16 . A tool for coupling a first prosthetic to a second prosthetic, said tool comprising:
 a first arm having a first bearing surface configured to apply a force in a first direction;   a second arm having a hook shaped member having a second bearing surface configured to apply a force in a second direction opposite the first direction, said first and second arms being generally parallel, said first arm being translatable with respect to the second arm; and   a translation force mechanism configured to apply force to the first and second arms so as to cause generally parallel translation of the first and second arms.   
     
     
         17 . The tool for prosthesis system of  claim 16  wherein the first bearing surface is circular and configured to apply forces to a resected radial bone. 
     
     
         18 . The tool for prosthesis system of  claim 17  wherein a track and a slider define the single axis. 
     
     
         19 . The tool for prosthesis system of  claim 16  wherein the first arm comprises a handle and a hinge. 
     
     
         20 . The tool for prosthesis system of  claim 16  wherein the first arm comprises a pushing member.