1. The Accuracy and Advantages of Computer Navigation in High Tibial Osteotomy
Kinzel Vera FRACS
Parker David A FRACS
Hanson Curtis MD
Scholes Corey PhD
Coolican Myles RJ FRACS
1 Sydney Orthopaedic Research Institute
Australian Orthopaedic Association
70th Annual Scientific Meeting
Adelaide, 2010

2. Conflict of interest
We have no conflict of interest to report

3. High tibial osteotomy (HTO)
Used to correct lower limb malalignment
Alter mechanical axis of the lower limb
Treatment for knee OA
Unload damaged compartment
Transfer load to healthy cartilage

4. HTO Planning and assessment
Long-leg x-ray
Pre and post-op
Intraoperative
Jig-CW
Rod or cables
Fluroscopy
Limitations
Accuracy
Radiation
Inconvenience

5. Computer navigation Increasing use in orthopaedic surgery
Accuracy and reliability
Established in arthroplasty past 4 years
Real time information on coronal & sagittal plane alignment
Utilised in osteotomy past 4 years

6. TKR Navigation Usage in Australia*
*Source: Stryker Australia

7. Aim
Compare the accuracy of the traditional form of preoperative assessment with intraoperative and postoperative assessment of the alignment utilising a computer-based navigation system.

8. Methods 20 Patients ( 2 female, 18 male) Average Age: 50.4
All varus alignment - HTO medial opening wedge

9. Methods
Preop
Long leg standing A-P xray
Measured mechanical axis

10. Methods
Intraop
Percutaneous insertion of femoral and tibial tracker pins & registration of hip

11. Methods
Intraop
Arthroscopic registration of intraarticular landmarks via standard portals

12. Methods Intraop Registration of external landmarks
Osteotomy performed under continuous measurements via navigation until desired alignment achieved

13. Methods
Intraop
femoral head allograft and plate fixation

14. Methods
Postop
long leg standing A-P xrays
at 6 months postop.

15. Average lower limb alignment measured with x-ray and navigation
Varus
Valgus *
* Significantly different to navigation (p<0.05)

16. Individual differences in alignment measurements pre and post-operatively

17. Discussion Navigation assisted surgery is becoming more popular in
orthopaedic procedures
This study demonstrates that
use of navigation in osteotomy
yields result comparable but not
identical to those using
long Leg X Rays alone

18. Conclusion Navigation is Safe Reliable. Real time information
Useful for dynamic
monitoring during
lower limb osteotomies

19. Conclusion Navigation provides comparable information
in determining existing malalignment
postoperative correction in the coronal axis when compared to traditional methods

20. Thank you 20

21. Lower limb alignment measured with x-ray and navigation
Varus
Valgus

22. Differences in alignment measurements pre and post-operatively*
* Significant difference between pre-op and post-op (p<0.05)

23. Differences in future measurements of alignment (+/- Prediction intervals)