1. Navigation—computer-assisted surgery (CAS)
Published: September 2013
Authors: Rami Mosheiff, Iri Liebergall, IL, Jim Krieg, US
From the many slides provided below, please select the appropriate number of slides for your lecture given the allotted presentation time.
AO Trauma Advanced Principles Course

2. Learning objectives
Recognize instances during surgery that are favorable for introducing navigation
Define advantages and disadvantages of navigation
Evaluate indications for navigation that are evidence based
Teaching points:
Participants should be aware that navigation is no substitute for careful preoperative planning and that relying strongly on navigation may limit an individual´s general versatility while improving the exactness of specific procedures.

3. CAS for trauma care
2-D fluoro-based navigation: “drill guide navigation”
Fracture reduction
3-D fluoro-based navigation: intraarticular fractures
Pelvis and acetabulum

4. Computerized fluoroscopic navigation
2-D fluoro-based navigation: “drill guide navigation”
Example is screw placement in the pelvis
Goal is diminished fluoro time
Minimizing risk to health care team
Improving accuracy of screw placement

5. Navigation system Image processing computer system Localization
camera array

6. Calibration target LED tracking enables precise localization of C- arm
Radiation sensors allow automatic image acquisition
Calibration grid appear in images and are automatically erased

7. Tracked instruments

8. Optical tracking principle
The instruments are equipped with a shield on witch four LEDs are mounted. The camera tracks the LEDs. Precision is 0.1 mm at about 2 meters distance.
These instruments are tracked by a camera.
(See the expert part for characteristics of the camera)
If some participants comment about the size of the camera, then you can reply that:
Some may say that this camera is very big, but only such a big camera can provide such precision!
...can track so many tools at once
...has such a large field of view
...big camera - small instruments

9. Attach reference frame

10. Aim camera

11. Acquire several images

12. Navigation

13. Multiimage navigation

14. Nail locking

19. Intraoperative planning of Poller screws

21. What kind of accuracy? Large bias + High precision
No bias + High precision
No bias + Low precision
Large bias + Low precision

24. Significantly better screw scattering
Significantly better screw parallelism
Better outcome?
Improved accuracy of screw placement. Unclear what benefit this may be in some applications.
References:
Liebergall M, Ben-David D, Weil Y, et al. Computerized navigation for the internal fixation of femoral neck fractures. J Bone Joint Surg Am Aug;88(8):

25. Average fluoroscopy time
Standard fluoroscopy: 26 seconds
Virtual fluoroscopy: 6 seconds
(P < 0.01)
Decreased fluoro time. Improved safety for health care team.
References:
Collinge C, Coons D, Tornetta P, et al. Standard multiplanar fluoroscopy versus a fluoroscopically based navigation system for the percutaneous insertion of iliosacral screws: a cadaver model. J Orthop Trauma Apr;19(4):254-8.

26. CAS for trauma care
2-D fluoro-based navigation: “drill guide navigation”
Fracture reduction
3-D fluoro-based navigation: intraarticular fractures
Pelvis and acetabulum

27. Reduction—second generation
Khoury A, Mosheiff R, Beyth S, et al. Evaluation of the second generation of computer assisted orthopaedic fracture reduction. Proc. 7th Int. Conf. on Computer-Aided Orthopaedic Surgery, Heidelberg, Germany, June 2007.

31. Poller screw

35. Entry point

40. Fracture reduction

46. Measuring nail length

48. CAS for trauma care
2-D fluoro-based navigation: “drill guide navigation”
Fracture reduction
3-D fluoro-based navigation: intraaarticular fractures
Pelvis and acetabulum

49. 3-D fluoro-based navigation
unit
Siremobil
Iso-C-3D
Monitor

50. ISO-C-3D navigation in trauma
Camera
Reference guide
Preimaging orbital motion measurements.
References:
Atesok K, Finkelstein J, Khoury A, et al. CT (ISO-C-3D) image based computer assisted navigation in trauma surgery: A preliminary report. Injury Extra 01/2008; 39(2):39–43.

51. ISO-C-3D navigation in trauma
ISO-C in action for 3-D image navigation.
References:
Atesok K, Finkelstein J, Khoury A, et al. CT (ISO-C-3D) image based computer assisted navigation in trauma surgery: A preliminary report. Injury Extra 01/2008; 39(2):39-43.

52. ISO-C-3D navigation in trauma
Drilling through the navigated tool.

53. ISO-C-3D navigation in trauma
Drilling through the navigated drill guide.

54. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw

55. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

56. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

57. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

58. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

59. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

60. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

61. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

62. CT-like intraoperative navigation
Virtual 3-D screw insertion of first screw.

63. ISO-C-3D navigation in trauma
K-wires inserted accordingly.

64. Definitive screw fixation
Two cannulated screws.

65. 11% fracture fixations were judged to require intraoperative revision
The mean additional operative time was 7.5 min
Combining ISO-C-3D with computer navigation can improve safety and decrease invasiveness
References:
Atesok K, Finkelstein J, Khoury A, et al. CT (ISO-C-3D) image based computer assisted navigation in trauma surgery: A preliminary report. Injury Extra 01/2008; 39(2):39–43.
Atesok K, Finkelstein J, Khoury A, et al. The use of intraoperative three-dimensional imaging (ISO-C-3D) in fixation of intraarticular fractures. Injury Oct;38(10):1163–1169. Epub 2007 Sep 19.

66. Limitations
Small field of view
103cm
Large patient
Small patient

67. CAS for trauma care
2-D fluoro-based navigation: “drill guide navigation”
Fracture reduction
3-D fluoro-based navigation: intraarticular fractures
Pelvis and acetabulum
References:
Mosheiff R, Khoury A, Weil Y, et al. First generation computerized fluoroscopic navigation in percutaneous pelvic surgery. J Orthop Trauma Feb;18(2):106–111.

68. Acquired images Screw type Sacroiliac 2–3 Ramus-pubis 3–4
Number of images
Sacroiliac
2–3
Ramus-pubis
3–4
Transvers/iliac
Posterior column

76. Indications Cases of minimally displaced fractures
Feasible closed reduction
Combination of closed and open reduction
References:
Mosheiff R, Khoury A, Weil Y, et al. First generation computerized fluoroscopic navigation in percutaneous pelvic surgery. J Orthop Trauma Feb;18(2):106–111.

77. Hi-tech methods Advanced preplanning capabilities
Improved accuracy of implant placement
Reduction in radiation exposure
Educational and quality control tool
Employment in all stages of surgery
Proper combination of methods

78. Take-home messages
As computer-assisted surgical technology evolves, there may be some benefit to orthopedic trauma surgery
Indications are evolving
Advantages may include:
Decreased radiation exposure
Safer/more accurate implant placement
Navigation is no substitute for careful preoperative planning