Abstract: Objective    To build a detection system of tibiofemoral joint in vivo based on robotic arm ultrasonic imaging combined with registration of CT images to ultrasound images technology and evaluate the accuracy of the system.    Methods   CT and ultrasound images of pork tibiofemoral joints and femur were collected and registered after three-dimensional reconstruction. After femur’s movement at six degrees of freedom, ultrasound images were collected and reconstructed and then registered to CT three-dimensional model. The displacement between CT three-dimensional model and real displacement were compared to calculate registration accuracy. The registration and accuracy calculation were implemented by two researchers to calculate intraclass correlation coefficient.   Results    It was feasible to use three-dimensional geometric information for ultrasound-CT manual registration to build a detection system of tibiofemoral joint in vivo. Translation accuracy ranged from 0.94 mm to 1.16 mm, and rotation accuracy ranged from 0.63 ° to 1.50 °. Intraclass correlation coefficient was 0.794 (P=0.014).    Conclusions    The ultrasound-CT registration method proposed in this article is feasible, and the accuracy can meet the requirements of tibiofemoral dynamic detection. In the future, we need to further improve the method of ultrasound images’ obtaining by robotic arm and use computer image processing technology for fast registration research.

Key words: 3D/3D image registration; ,  , Robotic arm ultrasonic imaging; ,  , Tibiofemoral joint