Global biomechanical evaluation during work and daily-life activities

摘要

Advances in technology in the last few decades have made it possible to observe human behavior in three dimensions with great spatial accuracy. Image-based methods for measuring human motion have been developed, such as opto-electronic techniques. Unfortunately, in the work environment these methods are complicated to set up and they can only easily be applied in the laboratory. However, electronic sensors such as accelerometers and gyroscopes, or flexible angular sensors are now available to tackle the main outdoor application problems of image-based methods. These sensors have been used for 3D measurements of the lower and upper segments of the trunk, during standing, walking and rising from a chair, in normal and pathological conditions. In the present study we used a device including accelerometers and gyroscopes to calculate the angular behavior of the pelvis on the sagittal, frontal and horizontal planes, measuring angle tracks and angular excursions during walking, gait initiation and termination, seat-to-stand and stand-to-seat, squat, standing anterior and lateral reaching and grasping, anterior and lateral trunk flexion and trunk rotation. Assessment of pelvis positions at rest and during movement is useful for improving our understanding of motor strategies at work and preventing injuries (e.g. low back pain) and mechanical whole-body fatigue. The devices were placed directly on the skin over the sacrum. The calculated angles were compared to those computed by a high-quality optical motion analysis system consisting of eight infrared ray cameras (operating at 120 fps) to detect the movements in three-dimensional space of three retro-reflective markers (15-mm diameter) placed on the skin over the sacrum and the right and left anterior superior iliac spinae. To compare the ranges of motion (ROM) we used the root mean squared error (RMS); the coefficient of multiple correlation (CMC), i.e. the positive square root of the adjusted coefficient of multiple determination, was used to evaluate overall waveform similarity of instantaneous angle curves. The closer to 1 the CMC, the more similar the waveforms. Preliminary results indicated substantial similarity between the extracted angle tracks (anterior-posterior behavior on the sagittal plane, pelvic obliquity and intra-extra rotation of the pelvis) in all tasks. Errors in the corresponding ROMs were low. This appears to be an accurate, inexpensive and simple method to measure the kinematics of the pelvis during common work and daily-life activities.