The Accuracy and Advantages of Computer Navigation in High Tibial Osteotomy

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

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)