Orthopaedic physical examination assisting system for improvement of accuracy and reproducibility of knee laxity diagnosis

In this study, to improve accuracy and reproducibility of knee laxity diagnosis, Orthopaedic physical examination assisting system was developed. The system enables the surgeon to monitor the force vector added by himself and the posture of the knee in real-time. The advantage of the developed system is to quantify the normal orthopaedic physical examination, without any modification, which is accustomed to general orthopaedic surgeons. The force vector added to the shank by a surgeon is measured with 3 axis force sensor and 6DOF magnetic tracker FASTRAK, and 6DOF knee joint motion of the patient is measured with two FASTRAK receivers which are attached on its thigh and shank. In this system, to describe the 6DOF knee motion, Femoral and tibial coordinate systems are defined with bony landmark which is easily palpated and are registered to the thigh or shank receiver coordinate system by homogeneous transformation matrix which is acquired by the special stylus. To evaluate the effectiveness of the system, the posterior drawer test with the system was done by 5 young healthy people. The evaluation parameters were knee posture, load magnitude and load position during the experiment. The result showed examination accuracy was significantly improved in all evaluation parameters.