Soft-tissue Artefact Assessment and Compensation in Motion Analysis by Combining Motion Capture Data and Ultrasound Depth Measurements

摘要

Accurately determining the hip joint centre is a necessary component in biomechanical human motion analysis to measure skeletal parameters and describe human motion. The hip joint centre can be estimated using functional methods based on the relative motion of the femur to pelvis using reflective markers attached to the skin surface through an optical motion capture system; but this suffers inaccuracy due to the soft tissue artefact. A key objective in movement analysis is the assessment and correction of this artefact; in this case we present a non-invasive method to assess and reduce the soft tissue artefact effects using optical motion capture data and tissue thickness from ultrasound measurements during flexion, extension, and abduction of the hip joint. Results show that the displacement of markers is non-linear and larger in areas closer to the hip joint. The marker displacements are dependent on the movement type, being relatively larger in abduction movement. The quantification of soft tissue artefacts is used as a basis for a correction procedure for hip joint centre and minimizing effects. Results show that our method for soft tissue artefact assessment and minimization reduces the error in the functional hip joint centre approximately from 13-23mm to 7-14mm.