Augmented marker tracking for peri-acetabular osteotomy surgery

Abstract

Objective

To develop a hybrid augmented marker-based navigation system for acetabular reorientation during peri-acetabular osteotomy (PAO).

Methods

The system consists of a tracking unit attached to the patient's pelvis, augmented marker attached to the acetabular fragment and a host computer to do all the computations and visualization. The augmented marker is comprised of an external planar Aruco marker facing toward the tracking unit and an internal inertial measurement unit (IMU) to measure its orientation. The orientation output from the IMU is sent to the host computer. The tracking unit streams a live video of the augmented marker to the host computer, where the planar marker is detected and its pose is estimated. A Kalman filter-based sensor fusion combines the output from marker tracking and the IMU. We validated the proposed system using a plastic bone study and a cadaver study. Every time, we compared the inclination and anteversion values measured by the proposed system to those from a previously developed optical tracking-based navigation system.

Results

Mean absolute differences for inclination and anteversion were 1.34 ( \(\pm \,1.50\) ) and 1.21 ( \(\pm \, 1.07\) ) \(^\circ \) , respectively, for the cadaver study. Mean absolute differences were 1.63 ( \(\pm \,1.48\) ) and 1.55 ( \(\pm \,1.49\) ) \(^\circ \) for inclination and anteversion for the plastic bone study. In both validation studies, very strong correlations were observed.

Conclusion

We successfully demonstrated the feasibility of our system to measure the acetabular orientation during PAO.