Implantable marker for a surgical navigation system, the marker having a spike for removably securing the marker to the tissue to be tracked

Abstract

A marker for use with a surgical navigation system for tracking the tissue with which the marker is associated. The overall dimensions of the mark is such that it is shaped to be disposed below the skin of the patient in which the marker is implanted. The marker has a stem or a spike that allows the marker to be implanted in hard tissue such as bone. A head, containing navigation system components is located above the stem or spike. Once the procedure is completed the marker is removed from the patient by breaking the head free from the stem Alternatively the head may be rotated to cause the whole of the marker to break free from the bone in which the marker is implanted.

1 . A tissue marker for use with a surgical navigation system, said tissue marker including:
 a body the body including an interface component for holding the marker to the tissue the position of which is to be tracked;   navigation system components attached to the body for exchanging signals with a navigation system so that the position and orientation of the body can be determined, wherein the body including said navigation components attached to said body are dimensioned to be located below the skin; and   a flexible tether that extends from said body, said tether dimensioned to extend above the skin and attached to the body so that, when a force is applied to the tether, said tether applies a pull force on the body without applying a torque force.   
     
     
         2 . The tissue marker of  claim 1 , wherein the navigation system components are configured to receive signals broadcast by a complementary navigation system component located above the skin. 
     
     
         3 . The tissue marker of  claim 1 , wherein the navigation system components are configured to emit or detect the presence of EM or RF energy. 
     
     
         4 . The tissue marker of  claim 1 , further including at least one conductor that extends from the body for electrically connecting the navigation components in the body to complementary navigation system components located above skin level. 
     
     
         5 . The tissue marker of  claim 4 , wherein said tether and said at least one conductor are contained in a common sheath that extends from the body to above the skin level. 
     
     
         6 - 18 . (canceled) 
     
     
         19 . A marker for use with a surgical navigation system, said marker including:
 a head;   transducer components disposed in said head for receiving EM or RF signals from a complementary navigation system component or transmitting EM or RF signals to a complementary navigation system component; and   a stem formed from biocompatible material that extends outwardly from said head, said stem having features for engaging bone so that the stem is held to the bone and a separation section that, in comparison to an adjacent portion of said stem, is of lower mechanical strength so that, when an extraction force is applied to said head, said stem separates at the separation section so that head can be withdrawn away from said stem features that hold said stem to the bone.   
     
     
         20 . The marker of  claim 19 , wherein the stem separation section is formed so that in comparison to the rest of said stem, the separation section is of low tensile strength. 
     
     
         21 . The marker of  claim 19 , wherein said head is formed with features to which a removal tool can engage. 
     
     
         22 . The marker of  claim 19 , wherein said stem has a proximal end adjacent said head and a distal end spaced from said head and the stem separation section is adjacent the proximal end of said stem. 
     
     
         23 . The marker of  claim 19 , wherein said stem is formed with barbs that hold said stem to the bone. 
     
     
         24 . The marker of  claim 19 , wherein said stem is formed with indentions, the indentations defining the stem separation section.