On-site verification of implant positioning
A method verifying the position of a surgically inserted orthopedic insert. A preoperative three dimensional image data set of the surgical site is generated, showing the bone into which the insert is to be inserted. During the insertion procedure, a series of intraoperative two-dimensional fluoroscope images are generated, each at a known pose relative to the bone, showing the insert during or after insertion into the bone. The 3-D position of the insert is determined in an intraoperative three dimensional image data set reconstructed from the series of intraoperative 2-D fluoroscope images. The reconstructed intraoperative 3-D image data set is registered with the preoperative three dimensional image data set, such as by comparison of imaged anatomical features. Once this registration is achieved, the determined 3-D position of the insert is used to implant a virtual image of the insert into the preoperative three dimensional image data set.
1. A method of intraoperatively verifying the position and orientation of an intraoperatively inserted orthopedic insert, comprising:
generating a preoperative three dimensional image data set showing at least a bone in which said insert is to be inserted;
generating a plurality of intraoperative two-dimensional fluoroscope images showing said insert and said bone, each image taken at a known orientation and position relative to said bone;
reconstructing from said plurality of intraoperative two-dimensional fluoroscope images, an intraoperative three dimensional image data set including the three dimensional position and orientation of said insert;
registering said intraoperative three dimensional image data set with said preoperative three dimensional image data set;
using said previously determined registration to modify said preoperative three dimensional image data set by insertion therein of the three dimensional position and orientation of said insert; and
generating at least one two dimensional image from said modified preoperative three dimensional image data set, with a virtual image of said intraoperatively inserted orthopedic insert implanted therein,
such that the position and orientation of said intraoperatively inserted orthopedic insert may be verified intraoperatively on an image having the characteristics of a preoperatively generated image.
2. A method according to claim 1 , further comprising:
defining on said preoperative three dimensional image data set the planned position and orientation of said insert relative to said bone; and
comparing said implanted virtual image of said insert in said preoperative three dimensional image data set with said planned position and orientation of said insert relative to said bone.
3. A method according to claim 1 , wherein said registering is performed by comparing anatomical features determined from said at least one intraoperative three dimensional image data set with corresponding features on said preoperative three dimensional image data set.
4. A method according to claim 1 , wherein said registering is performed by comparing intensity features determined from said at least one intraoperative three dimensional image data set with corresponding features on said preoperative three dimensional image data set.
5. A method according to claim 1 , wherein said at least one bone is a vertebra, and said insert is a pedicle screw, an obliquely inserted screw, or an artificial disc.
6. A method according to claim 1 , wherein said preoperative three dimensional image data set is either a CT data set or an MRI data set.
7. A method according to claim 1 , wherein said plurality of intraoperative two-dimensional fluoroscope images taken at known orientations and positions is obtained using a C-arm system.
8. A method according to claim 1 , wherein said known orientations and positions of said plurality of intraoperative two-dimensional fluoroscope images are determined by analyzing images of a three dimensional target disposed in a fixed position relative to said bone, and featured in said plurality of intraoperative two-dimensional fluoroscope images.
9. A method according to claim 8 , wherein said three dimensional target comprises radiographically opaque markers having predetermined mutual positions.
10. A method according to claim 1 , wherein said known orientations and positions of said plurality of intraoperative two-dimensional fluoroscope images are determined by use of an optical system tracking the orientation and position of the system generating said fluoroscope images.
11. A method according to claim 1 , wherein said known orientations and positions of said plurality of intraoperative two-dimensional fluoroscope images are determined by use of orientation sensors on the system generating said fluoroscope images.
12. A method according to claim 1 , wherein said plurality of intraoperative two-dimensional fluoroscope images is a video sequence of images.
13. A method according to claim 1 , wherein the intraoperative position and orientation of said insert, as determined in said plurality of intraoperative images, is virtually displayed in said three dimensional image data set obtained preoperatively without said insert.
14. A method according to claim 1 , wherein said plurality of intraoperative two-dimensional fluoroscope images, each taken at a known orientation and position relative to said bone, shows said insert during insertion into said bone or on completion of insertion into said bone.