The calculation of symmetry in amputee gait is a valuable tool to assess the functional aspects of lower limb prostheses and how it impacts the overall gait mechanics. This paper analyzes the vertical trajectory of the body center of mass (CoM) of a group formed by transfemoral amputees and non-amputees to quantitatively compare the symmetry level of this parameter for both cases. A decomposition of the vertical CoM into discrete Fourier series (DFS) components is performed for each subject’s CoM trajectory to identify the main components of each pattern. A DFS-based index is then calculated to quantify the CoM symmetry level. The obtained results show that the CoM displays different patterns along a gait cycle for each amputee, which differ from the sine-wave shape obtained in the non-amputee case. The CoM magnitude spectrum also reveals more coefficients for the amputee waveforms. The different CoM trajectories found in the studied subjects can be thought as the manifestation of developed compensatory mechanisms, which lead to gait asymmetries. The presence of odd components in the magnitude spectrum is related to the asymmetric behavior of the CoM trajectory, given the fact that this signal is an even function for a non-amputee gait. The DFS-based index reflects this fact due to the high value obtained for the non-amputee reference, in comparison to the low values for each amputee.
Spinal cord injured (SCI) patients that have no lower limb motor function perform several transfers during a day. Those transfers are from and to a wheelchair, a car, a hygienic chair, among other situations. These repetitive motions can cause overload on their upper limbs over time. Functional Electrical Stimulation may be used to induce contraction on knee extensors, providing additional support at the joint level during transfer. However, the design of the interface with which to control the onset of stimulation is challenging. The use of some automated system is beneficial, particularly since the user is using both hands to perform the transfer. Therefore, the precise moment of activation is important because, if erroneous, it can cause the user's loss of balance. A system with which the users themselves can activate the stimulation with triggers in gloves is used to collect kinematic data from SCI patients during Sitting Pivot Transfers. The results show that the trunk angle can be used along a threshold for a reliable assistance device. Strategies for portability using a wireless inertial measurement unit are also discussed.
Transfer is a key ability and allows greater interact with the environment and social participation. Conversely, paraplegics have great risk of pain and injury in the upper limbs due to joint overloads during activities of daily living, like transfer. The main goal of this study is to verify if the use of functional electrical stimulation (FES) in the lower limbs of paraplegic individuals can assist the sitting pivot transfer (SPT). The secondary objective is to verify if there is a greater participation of the lower limbs during lift pivot phase. A preliminary study was done with one complete paraplegic individual. Temporal parameters were calculated and a kinetic assessment was done during the SPT. The preliminary results showed the feasibility of FES for assisting the SPT.
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