Precision analysis of an intelligent skin marker for non-invasive kinematic analysis of knee joints

Kinematic analysis of normal and artificial knee joints is an important diagnostic tool for the orthopaedic research community. Abnormal motion in a knee joint gives rise to pain and eventually causes chronic injury. Currently the standard way to measure the motion of bones in a knee joint with high precision is by implanting tantalum beads in the bones prior to imaging using X-ray equipment. This technique is invasive and the required exposure to ionizing radiation imposes a significant cancer risk. Moreover, during the procedure the patient cannot perform normal everyday activities due to their confinement to the limited field of view of the X-ray equipment. In this paper, we propose a non-invasive US-US registration based framework which can successfully capture motion of bones in a knee joint with the required precision using dynamic images produced by dual ultrasound transducer arrays. Our results show that this approach is capable of producing the precision required for 3D kinematic analysis of knee joint without the requirement for any invasive procedures and can be used while the patient performs normal activities.