Fig. 6.

Illustration of angle differences in YZ- and XZ- planes. Blue plane shows the surgical planned cutting plane while red plane is the practical model cutting plane. A, B demonstrate the angle difference between red and blue cutting planes when a metal jig was used. C, D illustrate the angle difference between red and blue cutting planes when conventional navigation system was used. E, F exhibit the angle difference between red and blue cutting planes when AR navigation system was employed