Device for fixing a rod to a thin bone wall

Abstract

The invention concerns an implantable device for fixing a rod in a rather thin bone wall comprising two parts, each comprising a body with a passage for receiving the rod, and a curved hook extending laterally relative to the body. Each hook is shaped such that the two hooks facing each other can be simultaneously inserted, by mutually titling the two parts urging their bodies closer to each other, in an opening arranged in the wall, and be mutually spaced rearwards as said bodies are brought closer to each other. The rod received in said passages of the two bodies is capable of preventing any reverse tilting of said parts. The invention is particularly useful for fixing a rod for backbone osteosynthesis in the flat part of the skull occipital bone.

1 . An implantable device for fixing a rod to a thin bone wall, in particular for fixing a rod of a system for osteosynthesis of the spine to the wall of the occipital bone of the skull, the device comprising a rod and first and second parts each of said first and second parts comprising both a body in which there is formed a passage for receiving the rod, and also a curved hook extending laterally relative to the body, each hook is of a shape such that the two hooks when placed face to face can be inserted simultaneously into an opening formed in said bone wall, the hooks being inserted by tilting the two parts in opposite directions so as to tend to move their bodies towards each other, the hooks moving away from each other behind said wall as said bodies move towards each other, and in that said passages of the two bodies come into alignment once the bodies have come together with the parts in mutual contact, and the rod is suitable for being received therein, thereby preventing said parts from tilting in the opposite direction.  
     
     
         2 . The device according to  claim 1 , wherein the body of each part is generally oval in shape with at least one plane face, and in that said bodies are suitable for being placed essentially in contact with each other via their face plane faces so as to ensure that both passages are in axial alignment.  
     
     
         3 . The device according to  claim 2 , wherein each hook has a root region extending from the vicinity of said plane face, essentially at right angles relative to the axis of the passage, and an end portion extending substantially parallel to the axis of the passage.  
     
     
         4 . The device according to  claim 3 , wherein the overall size of each hook as measured in a direction parallel to the axis of the corresponding passage is greater than the thickness of the body in said direction.  
     
     
         5 . The device according to  claim 4 , wherein the body has a second plane face substantially parallel to the first plane face.  
     
     
         6 . The device according to  claim 1 , wherein each hook is of a thickness that tapers progressively away from its root portion towards its free end.  
     
     
         7 . The device according to  claim 1 , wherein each hook is of a width that is substantially constant over its entire extent.  
     
     
         8 . The device according to  claim 1 , wherein each part includes means for locking the rod in its passage.  
     
     
         9 . The device according to  claim 8 , wherein the locking means comprise a screw engaged in tapping formed in the body and opening out into the passage.  
     
     
         10 . The device according to  claim 1 , wherein the two parts are identical.