Instrument guidance system for spinal and other surgery

Abstract

A method and apparatus for positioning a surgical instrument during stereotactic surgery on a body, for example, during spinal surgery or general surgery. A mounting device is attached to a bone structure of the body, for example, by attaching a rail to the spine for spinal surgery, or a mounting plate and a rod attached to the mounting plate. In spinal surgery, the rail is attached to the spine by clamping the rail to two spinous processes and adjusting the separation of the two spinous processes to match the separation of the two processes in three-dimensional scanned image, thereby matching a curvature of the spine with a corresponding curvature of the spine in the image. Multiple of fiducial points are located on the body in relation to the mounting device. An adjustable guidance fixture that includes an instrument guide for guiding the surgical instrument along a constrained trajectory relative to the instrument guide is attached to the mounting device. A location and orientation of the instrument guide is tracked and a position of the constrained trajectory in the three-dimensional image is computed. The guidance fixture is adjusted relative to the mounting device using a first constrained motion followed by a second constrained motion, so that the constrained trajectory of the instrument guide passes through the target.

What is claimed is:  
     
         1 . An apparatus for stereotactic surgery on a spine comprising: 
 a guidance fixture including an instrument guide for moving a surgical instrument along a constrained trajectory;    a mounting device including a longitudinal rail and a plurality of clamps for securing the longitudinal rail to the spine;    an adjustment mechanism for adjusting a location and an orientation of the constrained trajectory relative to the mounting device; and    a signaling device for providing signals related to the location and the orientation of the constrained trajectory.    
     
     
         2 . An apparatus for stereotactic surgery on a body, comprising: 
 a guidance fixture, including 
 (a) an instrument guide for moving a surgical instrument along a constrained trajectory relative to the instrument guide,  
 (b) an adjustable portion supporting the instrument guide, including a base having a central axis and an adjustment mechanism coupled between the base and the instrument guide, wherein a configuration of the adjustment mechanism determines an orientation of the instrument guide relative to the central axis of the base, and  
 (c) a signaling device for providing a signal representation of the configuration of the adjustment mechanism; and  
   a mounting device coupled to the guidance fixture for attaching the guidance fixture to the body, the mounting device including an attachment portion for rigid attachment to a bone structure of the body.    
     
     
         3 . The apparatus of  claim 2  wherein the attachment portion of the mounting device includes a first clamp for attaching the mounting device to a first point on a spine, and the mounting device further includes a longitudinal rail.  
     
     
         4 . The apparatus of  claim 3  wherein the attachment portion includes a second clamp for attaching the mounting device to a second point on the spine.  
     
     
         5 . The apparatus for  claim 3  wherein the mounting device further includes a transverse rail coupled between the longitudinal rail and the guidance fixture and an adjustable coupler coupling the longitudinal rail and the transverse rail.  
     
     
         6 . The apparatus of  claim 2  wherein the mounting device further includes a tracking device which when the mounting device attached to the body is rigidly coupled to the body, the tracking device providing a signal representation of a position of the body.  
     
     
         7 . The apparatus of  claim 6  wherein the tracking device includes a plurality of tracking markers and the signal representation of the position of the body includes a plurality of signals propagating from corresponding tracking markers.  
     
     
         8 . The apparatus of  claim 7  wherein the signals propagating from the tracking markers are electromagnetic signals.  
     
     
         9 . The apparatus of  claim 8  wherein the tracking markers are light emitting diodes and the signals propagating from the tracking markers are optical signals.  
     
     
         10 . The apparatus of  claim 7  wherein the signals propagating from the tracking markers are acoustic signals.  
     
     
         11 . The apparatus of  claim 2  wherein the mounting device further includes and an adjustable portion coupling the attachment portion to the guidance fixture.  
     
     
         12 . The apparatus of  claim 2  wherein the attachment portion includes a mounting plate for attaching the mounting device directly to a bone structure of the body.  
     
     
         13 . The apparatus of  claim 12  wherein the mounting device further includes a rod removably attached to the mounting base.  
     
     
         14 . A method for stereotactic spinal surgery comprising: 
 attaching a longitudinal rail to a spine; 
 registering the longitudinal rail, including locating a plurality of anatomical fiducial points on the spine in relation to the longitudinal rail;  
 providing an adjustable guidance fixture that includes an instrument guide for guiding the surgical instrument along a constrained trajectory relative to the instrument guide;  
 attaching the adjustable guidance fixture to the longitudinal rail;  
 tracking a location and an orientation of the instrument guide relative to the longitudinal rail; and  
 adjusting the orientation of the instrument guide such the constrained trajectory passes through a target in the body.  
   
     
     
         15 . The method of  claim 14  further comprising driving the surgical instrument along the constrained trajectory toward the target.  
     
     
         16 . The method of  claim 14  wherein attaching the longitudinal rail to the spine includes attaching said rail to a first spinous process.  
     
     
         17 . The method of  claim 16  wherein attaching the rail to a first spinous process includes clamping said rail to said spinous process.  
     
     
         18 . The method of  claim 17  wherein attaching the longitudinal rail to the spine further includes attaching said rail to a second spinous process.  
     
     
         19 . The method of  claim 18  wherein attaching the longitudinal rail to the spine further includes adjusting the separation of the first and the second spinous processes to match a desired curvature of the spine.  
     
     
         20 . The method of  claim 19  wherein attaching the longitudinal rail to the spine further includes verifying locations a plurality of anatomical fiducial points on the spine in relation to the longitudinal rail.  
     
     
         21 . The method of  claim 14  further comprising attaching a tracking device to the rail, and locating the anatomical points in relation to the rail includes locating the tracking device and the anatomical points using a remote sensing device.  
     
     
         22 . The method of  claim 14  wherein including locating a plurality of anatomical fiducial points on the spine in relation to the longitudinal rail includes: 
 tracking a location of the longitudinal rail with using a remote sensing device;  
 tracking a location of a probe positioned at each of the fiducial points using the remote sensing device; and  
 comparing the location of the probe and the location of the longitudinal rail at each of the fiducial points.  
 
     
     
         23 . The method of  claim 22  further comprising attaching a tracking device to the rail, and wherein tracking a location of the longitudinal rail using the remote sensing device includes locating the tracking device using the remote sensing device.  
     
     
         24 . The method of  claim 14  wherein the adjustable guidance fixture includes a base coupled to the instrument guide, said guidance fixture enabling a plurality of constrained adjustments of the instrument guide relative to the base.  
     
     
         25 . The method of  claim 23  wherein adjusting the orientation of the instrument guide includes using a first constrained motion of the constrained adjustments and then adjusting the guidance fixture using a second constrained motion of the constrained adjustments, so that the constrained trajectory of the instrument guide passes through the target.  
     
     
         26 . The method of  claim 25  wherein in adjusting the guidance fixture, the first of the constrained adjustments includes a rotation of the instrument guide about a central axis of the base, and the second of the constrained adjustments includes a pivoting of the instrument guide to adjust an angle of the instrument guide and the central axis.  
     
     
         27 . The method of  claim 14  further comprising: 
 providing a three-dimensional image of the spine;  
 computing a position of the constrained trajectory in the three-dimensional image based on the tracked location and orientation of the instrument guide;  
 displaying a planar section of the three-dimensional image of the body in conjunction with a representation of the constrained trajectory.  
 
     
     
         28 . The method of  claim 27  wherein the displayed planar section containing the target on the spine and the method further, and adjusting the orientation of the instrument guide includes: 
 adjusting the guidance fixture using a first constrained motion until the constrained trajectory of the instrument guide lies in a plane corresponding to the displayed planar section; and  
 adjusting the guidance fixture using a second constrained motion, such that the orientation continues to lie in the plane corresponding to the displayed planar section, until the constrained trajectory passes through the target point.  
 
     
     
         29 . The method of  claim 27  further comprising: 
 driving the surgical instrument along the constrained trajectory toward the target, including tracking a location of the surgical instrument and displaying the location of the surgical instrument in conjunction with the scanned image.