Simulation of the Gait of a Patient Specific Model of Post Polio Residual Paralysis (PPRP): Effect of the Orthosis

The aim of this present study was to develop a patient specific 3D musculoskeletal model to post polio residual paralysis (PPRP) subject. This model allows the effects of the lower limbs orthosis on the gait kinematics and kinetics to be quantified objectively. CT scan data were used to personalize the geometrical model and its inertial properties. Gait-based experimental protocol based on David's protocol was performed. Kinematics data were measured using VICON motion system with six infrared cameras. Ground reaction force and moments were acquired simultaneously using two AMTI forces platforms. A direct/inverse algorithm of BRB.LifeMod software was used to simulate healthy (standard model provided by LifeMod) and pathological gaits (PPRP). The comparison of healthy and PPRP subjects was carried out. The biomechanics effects of the orthosis device were studied on simulated joint angles and torques, muscle force, and experimental ground reaction forces. The results showed that the orthosis device reduces the amplitude of movement of PPRP subject. It increases the ground contact time of the PPRP subject. However, a strategy of compensation exhibits a greater joint angle of the PPRP subject. Moreover, PPRP subject supports greater joint torques and lower muscle force due to the blocked knee joint device. The biomechanic effects of the lower limb orthosis helps to prevent long-term the injuries and damages of the biological structures involved of the PPRP paralysis. Furthermore, the personalization of the inertial properties of segmental bodies was taken in account to improve the accuracy of the patient specific biomechanics modelling.