Rotary mill

Abstract

A rotary mill ( 2 ) comprising a body portion ( 4 ) having a milling surface ( 10 ) for milling a first bone, a guide portion ( 6 ) having a guide body ( 22 ), and inter-engageable guide formations ( 20, 24 ) formed on the body portion ( 4 ) and guide portion ( 6 ), the guide body ( 22 ) having a projection ( 7 ) which is adapted to hold a second bone ( 11 ) away from the rotary mill during the milling operation.

1 . A rotary mill comprising a body portion having a milling surface for milling a first bone, a guide portion having a guide body, and inter-engageable guide formations formed on the body portion and guide portion, the guide body having a projection which is adapted to hold a second bone away from the rotary mill during the milling operation. 
     
     
         2 . The rotary mill as claimed in  claim 1 , wherein the inter-engageable guide formations comprise a central bore extending along a rotary axis of the body portion and a guide peg extending from the guide body, the guide peg being operable to be received in the central bore of the body portion. 
     
     
         3 . The rotary mill as claimed in  claim 1 , wherein the projection is integrally formed with the guide body. 
     
     
         4 . The rotary mill as claimed in  claim 1 , wherein the projection comprises an arm which is shaped to receive the milling surface without impingement. 
     
     
         5 . The rotary mill as claimed in  claim 1 , wherein the projection is shaped to receive the milling surface closely over its full range of movement relative to the guide body. 
     
     
         6 . The rotary mill as claimed in  claim 1 , wherein the projection is provided with a recess on a first side which is adapted to accommodate the milling surface without impingement. 
     
     
         7 . The rotary mill as claimed in any preceding  claim 1 , wherein a second side of the projection may be polished chamfered or otherwise shaped to avoid damage to the second bone. 
     
     
         8 . The rotary mill as claimed in  claim 1 , wherein the projection is removeably attached to the guide body. 
     
     
         9 . The rotary mill as claimed in  claim 2 , wherein the projection extends from the guide body in a direction substantially parallel to a longitudinal axis of the guide peg. 
     
     
         10 . The rotary mill as claimed in  claim 1 , further comprising additional guide portions, each guide portion being of a different size to other guide portions. 
     
     
         11 . The rotary mill as claimed in  claim 2 , wherein the guide peg comprises an abutment surface operable to abut a corresponding abutment surface in the central bore of the body portion. 
     
     
         12 . The rotary mill as claimed in  claim 11 , wherein the abutment surface comprises a distal surface of the peg. 
     
     
         13 . The rotary mill as claimed in  claim 12 , wherein the guide body has substantially the form of a trial prosthesis component. 
     
     
         14 . The rotary mill as claimed in  claim 1 , wherein the guide body comprises a trail prosthesis component. 
     
     
         15 . The rotary mill as claimed in  claim 14 , wherein the guide body comprises a trial unicondylar femoral prosthesis component. 
     
     
         16 . The rotary mill as claimed in  claim 15 , wherein the guide body is operable to guide reaming of a region superior to the anterior edge of the guide body. 
     
     
         17 . The rotary mill as claimed in  claim 1 , wherein the inter-engageable guide formations comprise a central bore extending along a rotary axis of the body portion and a guide peg extending from the guide body, the guide peg being operable to be received in the central bore of the body portion, and wherein the projection is integrally formed with the guide body.