1. Correcting Parallax Errors to Improve Femoral Component Rotation in Knee Replacement Simon Talbot, PandelisDimitriou, Michael Mullen, Ross Radic, Rachel Zordan, John Bartlett info@simontalbot.com.au, EFORT 2014

2. Whiteside’s Line info@simontalbot.com.au, EFORT 2014

3. Sulcus Line info@simontalbot.com.au, EFORT 2014

4. Sulcus Line Whiteside’s Line • Mean 0.3° ER • SD 2.7°* • Range -4.9° to +4.7° • Outliers 32% • Mean 1.8° IR • SD 4.2°* • Range -11.8° to +7.8° • Outliers 43% *(F=5.82, p=0.017) info@simontalbot.com.au, EFORT 2014

5. Coronal Axis of the Sulcus LineCAxSL CAXSL – Mean 0.4° varus, SD 3.8°, 9.4° varus to 7.3° valgus info@simontalbot.com.au, EFORT 2014

6. Consequences • Parallax error explains variability in WL • Parallax error causes inaccuracy when referencing the trochlear groove in: - Computer navigation, average error 1°, up to 3.4° - PSI planning, average error 2.7°, up to 10.4° info@simontalbot.com.au, EFORT 2014

7. T piece info@simontalbot.com.au, EFORT 2014

8. TAG video info@simontalbot.com.au, EFORT 2014

9. Femoral Malrotation Rates Note: *significant at p≤ .05 info@simontalbot.com.au, EFORT 2014

10. Conclusions • Trochlear groove has a variable coronal alignment • Sulcus Line is not Whiteside’s Line • SL is more accurate than WL by removing parallax • Parallax error effects CAS and PSI planning • Trochlear Alignment Guide (TAG) removes errors • Combine SL and PCA for greater accuracy The author declares that a conflict of interest exists in respect of this work owing to ownership of a patent info@simontalbot.com.au, EFORT 2014