Non-invasive tracking of bones for surgery

Abstract

The described method for determining at least orientation of a pelvic bone in space and for tracking movement of the pelvic bone using a computer assisted surgery (CAS) system includes removably attaching, in a non-invasive manner, at least one reference marker, in communication with the CAS system, to a skin surface covering the pelvic bone. Registering at least orientation readings of the reference marker is then performed with respect to a fixed reference in a reference coordinate system, following which at least an orientation of the pelvic bone in the reference coordinate system is determined using the orientation readings of the reference marker. These steps are repeated to update the orientation readings while tracking the pelvic bone in space.

1 . A method for determining at least orientation of a pelvic bone in space and for tracking movement of the pelvic bone using a computer assisted surgery (CAS) system, the method comprising:
 removably attaching, in a non-invasive manner, at least one reference marker to a skin surface covering said pelvic bone, the reference marker being in communication with the CAS system;   registering at least orientation readings of said reference marker with respect to a fixed reference in a reference coordinate system;   determining at least an orientation of said pelvic bone in the reference coordinate system using said at least orientation readings of said reference marker; and   repeating the steps of registering and determining to update said at least orientation readings while tracking the pelvic bone in space.   
     
     
         2 . The method as defined in  claim 1 , wherein the step of removably attaching further comprises using an adhesive to adhere the reference marker to the skin surface covering the pelvic bone. 
     
     
         3 . The method as defined in  claim 2 , further comprising mounting the reference marker on a flexible support layer, and adhering the flexible support layer to the skin surface covering the pelvic bone. 
     
     
         4 . The method as defined in  claim 1 , wherein each said reference marker defines three axes which are determined and tracked by the CAS system to produce said orientation readings. 
     
     
         5 . The method as defined in  claim 1 , further comprising determining both the orientation and position of said pelvic bone in space using said CAS system. 
     
     
         6 . The method as claimed in  claim 5 , further comprising registering both orientation and position readings of said reference marker with respect to the fixed reference in said reference coordinate system, and using both the orientation and position readings to determine the orientation and position of the pelvic bone in space. 
     
     
         7 . A system for determining at least an orientation of a pelvic bone in space and tracking movement of the pelvic bone using a computer assisted surgery (CAS) system, the system comprising:
 at least one reference marker removably and non-invasively attachable to a skin surface covering the pelvic bone, said reference marker being in communication with the CAS system;   a fixed reference positioned in a reference coordinate system and used to identify at least an orientation of said reference marker in said reference coordinate system; and   the computer assisted surgery (CAS) system including:
 a sensing device adapted to register at least orientation readings of said reference marker in the reference coordinate system; and 
 a processing unit receiving said orientation readings from the sensing device and being operable to determine and determining at least the orientation of said bone. 
   
     
     
         8 . The system as defined in  claim 7 , wherein the reference marker has an adhesive thereon for removably and non-invasively attaching the reference marker directly to the skin surface covering the pelvic bone. 
     
     
         9 . The system as defined in  claim 7 , wherein said reference marker is mounted on a flexible support layer, the flexible support layer being secured to the skin surface covering the pelvic bone by an adhesive. 
     
     
         10 . A device for use with a computer assisted surgery (CAS) system to determine at least orientation of pelvic bone in a reference coordinate system and to track movement of the pelvic bone, the device comprising at least one reference marker removably and non-invasively attachable to a skin surface covering a pelvic bone, the reference marker being in communication with the CAS system such that the reference marker is detected and tracked in said reference coordinate system by the CAS system with respect to a fixed reference, said reference marker being adapted to provide at least orientation readings thereof to the CAS system such as to determine at least orientation of the pelvic bone in the reference coordinate system and permit the CAS system to track movement of the pelvic bone. 
     
     
         11 . The device as defined in  claim 10 , wherein said reference marker has an adhesive thereon for removably and non-invasively attaching the reference marker directly to the skin surface covering the pelvic bone. 
     
     
         12 . The device as defined in  claim 10 , wherein said reference marker is mounted on a flexible support layer, the flexible support layer being secured to the skin surface covering the pelvic bone by an adhesive.