Methods for Sitting Posture Evaluation: Static Posture and Applications

Pressure sores (PS), are frequent in subjects with spinal cord injuries, and to minimize PS these subjects must get used to frequently changing their posture; useful information to this aim may come by testing healthy subjects and studying their kinematic behaviour during long sitting sessions. Two different investigation systems have been developed to this aim in the Department of Mechanics and Aeronautics (DMA) of Rome University ‘‘La Sapienza’’: the two systems, a pressure map sensor arranged on a chair and a potentiometer-based device to measure trunk rotations at the base of the spine are shown in this paper and their outputs are compared and correlated. The behaviour of ten healthy subjects is then evaluated during a one hour sitting session for preliminary consideration: there is a postural change every 7.7 ± 6.7 minutes in the frontal plane and every 5.7 ± 2.7 minutes in the sagittal plane; pelvis movements can be resumed by Centre of Pressure (COP) displacements and the largest values of these displacements are 5.2 ± 2.4 cm in the frontal plane and 3.0 ± 1.4 cm in the sagittal plane; the largest rotations in the two planes are respectively 8.4 ± 0.7 and 20.7 ± 12.6. The results of the study are discussed and satisfactorily compared with literature results.