Joint kinematics and spatial–temporal parameters of gait measured by an ultrasound-based system

Since measuring and recording techniques were developed, gait analysis has been frequently used in almost all fields of human locomotion such as rehabilitation medicine, orthopaedics, sports science, and other related fields. The measuring range of usual ultrasound-based devices is limited because the ultrasound sources must be always in visual contact with the microphones (markers). Our technique for the expansion of the measuring range is presented. Our approach is based on a mechanical axiom, which states that the position and orientation of a segment of the human body is determined by an array of three points per segment. The position of an invisible anatomical point of the segment could be determined by its position in relation to the fundamental points, being in visible contact on the body segment. Before measurement, the position of investigated anatomical points in relation to the fundamental points has to be given by an ultrasound-based pointer. The position of fundamental points of each segment of the human body has to be measured during motion by the ultrasound-based device. A computer code calculates the position of anatomical points from the above data on-line. This approach provides an opportunity to investigate a discretional number and posture (lateral, medial, posterior and anterior) of anatomical points. Our model consists of 19 anatomical and anthropometrical points. Based on the spatial coordinates of the anatomical points investigated, the spatial–temporal parameters of gait and anatomical joint angles are estimated. No significant statistical difference was observed between the values presented and those found in literature. Several clinical applications can be proposed such as monitoring of rehabilitation progress after orthopaedic surgery and gait analysis in neurological diseases.