Surgical instrument

Abstract

A cutting block comprises a body having a top surface for guiding a saw blade, and a top plate connected to the body. The top plate can move between a first position in which the top plate is spaced apart from the body and a second position in which the top surface of the top plate is an extension of the top surface of the body. The top plate has first and second resiliently deformable arms extending from it, spaced apart along the top plate, and the body has first and second recesses formed in it extending substantially perpendicularly to the top surface of the body. The first and second arms on the top plate are inserted in the recesses so that the arms and the recesses define the path for movement of the top plate relative to the body between the first and second position.

1 . A cutting block for fixing relative to a bone for guiding a saw blade during a step in an orthopaedic surgical procedure in which the bone is cut, the cutting block comprising:
 a. a body having a top surface for guiding a saw blade,   b. a top plate which is connected to the body and which can move between a first position in which the top plate is spaced apart from the body and a second position in which the top surface of the top plate is contiguous with and an extension of the top surface of the body,   in which the top plate has first and second resiliently deformable arms extending from it, spaced apart along the top plate, and in which the body has first and second recesses formed in it extending substantially perpendicularly to the top surface of the body, in which the first and second arms on the top plate can be received so that the arms and the recesses define the path for movement of the top plate relative to the body between the first and second positions,   and in which each of the recesses has a profiled surface against which the respective deformable arm acts during movement of the top plate relative to the body between the first and second positions so as to cause the arm to deform, the deformation of each of the arms being greater when the top plate is in an intermediate position between the first and second positions than when it is in each of the first and second positions, so that the top plate is biased away from the intermediate position towards the first and second positions.   
     
     
         2 . The cutting block of  claim 1 , in which each of the first and second arms has a pin extending transversely from it, and in which the profiled surfaces are acted against by the pins. 
     
     
         3 . The cutting block of  claim 2 , in which each of the profiled surfaces is provided by a groove which is cut in a wall of the body. 
     
     
         4 . The cutting block of  claim 3 , in which each of the grooves is curved when viewed in the direction which is defined by the pin which slides in the groove. 
     
     
         5 . The cutting block of  claim 1 , in which the recesses are shaped so that each of the arms within its recess in the body is exposed, allowing a user to apply force to the arm to cause the arm to be deformed resiliently to facilitate of the top plate between its first and second positions. 
     
     
         6 . The cutting block of  claim 1 , wherein the top surface includes a raised lip and a pair of projections configured to define an inner guiding surface. 
     
     
         7 . The cutting block of  claim 6 , wherein the top surface includes a recess configured to accommodate the raised lip and a pair of apertures configured to receive respective ones of the pair of projections.